Dental Pulp

Development and components of the healthy dental pulp The dental pulp refers to a tissue on an individual’s teeth that is formed by propagating and condensing the neural crest cells of the dental papilla. Trowbridge and Kim (1998) pointed out that a fully grown dental pulp assumes the appearance of embryonic connective tissue. However, the dental pulp’s periphery consists of highly specialised cells.Advertising We will write a custom critical writing sample on Dental Pulp specifically for you for only $16.05 $11/page Learn More In addition, the pulp also has microcirculatory components and sensory innervations. Blood flows normally within the dental pulp and provides nutrients and oxygen to the teeth, while still transporting any wastes products for excretion. Bishop and Malhotra (1990) observed that the lymphatic vessels of the dental pulp drain out any excess interstitial fluid. The cell structure of the dental pulp comprises of fibroblas ts and the undifferentiated cells. In addition, the dental pulp also consists of white blood cells, macrophages, and dentritic cells. However, the healthy part of the dental pulp does not have mast cells, with their availability indicating some form of inflammation (Ivar Karin, 2007). Functions of the dental pulp The dental pulp has significant functions. For example, it defends the dentinal tubules from bacterial attack (Nagaoka et al. 1995). There is a remarkable difference in the mode that odontontic and dentinal fluid occupy the dentinal tubules of teeth with vital pulps and those with necrotic pulps. For example, teeth with vital pulps are fully occupied as opposed to the teeth that have necrotic pulps. According to Linden et al. (1995) and Vongsavan (1993), dentinal fluid refers to ‘positively charged hydrogel’ with the capacity to prevent bacteria from attacking the pulp. In addition, the flow of the dentinal fluid, according to Linden et al. (1995) and Vongsava n (1993), determines the rate at which harmful substances enter into the dentinal tubules from the oral cavity. Thus, the dentinal fluid dilutes toxins, excretes any invading bacteria, as well as offers defensive support to the dentinal tubules because it has antimicrobial and antibodies to prevent the infection of the dentinal tubules (Trowbridge Kim, 1998). The dental pulp has specialised cells, the undifferentiated mesenchymal and odontoblasts cells, that have the capacity to protect the dental pulp from threats of trauma or caries. Such a function can be attributed to the fact that these cells form a hard tissue barrier over the pulp.Advertising Looking for critical writing on dentistry? Let's see if we can help you! Get your first paper with 15% OFF Learn More In addition, the dental pulp contains the necessary constituents for recognizing and breaking down antigens (Jontell Bergenholtz, 1992; Jontell et al., 1988; Jontell et al., 1987; Jontell et al., 1998). Al ongside the presence of neural, the dental pulp also has proprioceptive capability. Usually, an individual in need of dental attention might start experiencing excessive dental painful due to sensory stimuli. The presence of proprioceptive receptors within the pulp ensures the detection and reduction of impacts of masticatory forces within an individual’s teeth. The receptors initiate immediate withdrawal reflexes (Byers Narhi, 1999; Dong et al., 1985). Evidently, these features add to the defensive role of the dental pulp, as well as the continual protection it provides on an individual’s dentition (Matsutani et al., 2000; Paphangkorakit Osborn, 1998). Figure 1: Tooth anatomy. Innervations of the dental pulp It is important to understand the features of dental pulp innervations. The trigeminal nerve has the alveolar branches, which supplies neural to the teeth. On the other hand, the lower and upper jaws are supplied by the mandibular and maxillary branches respect ively (Abd†Elmeguid Yu, 2009). The dental pulp contains a network of tissues that comprise of the sensory trigeminal afferent axons (Byers 1984; Byers Narhi 1999) and sympathetic fibres (Kim et al., 1989). The flow of blood within the dental pulp is regulated by the sympathetic fibres, whose source is the cervical sympathetic ganglion. However, the trigeminal ganglion holds the cell bodies of the sensory neurons of the dental pulp (Ingle, 2008).Advertising We will write a custom critical writing sample on Dental Pulp specifically for you for only $16.05 $11/page Learn More The apical foramen forms the entry point of numerous axons, after which they branch with respect to the configuration of the blood vessels. When they reach the coronal dentin, the nerve bundles further, branches and moves apart in the direction of the pulp-dentition junction to form the plexus of Raschkow (Dahl Mjor, 1973; Gunji, 1982). The unmyelinated C fibres and the myeli nated A fibres form the sensory nerve fibre network (Dahl Mjor, 1973; Gunji, 1982; Miyoshi et al., 1966). However, most of the dentition consists of the myelinated A fibres which are further classified as either AÃŽ ´ (representing 90% of the A fibres) or AÃŽ ² fibres. The AÃŽ ´ fibres have little sensitivity as compared to the AÃŽ ² in terms of stimulation. On the other hand, the C fibres are found in the pulp proper, as well as have an extension to the cell†free zone (Byers Dong, 1983). The excitation threshold of AÃŽ ´ and AÃŽ ² fibres is lower that the excitation threshold of C fibres. For this reason, AÃŽ ´ and AÃŽ ² fibres can adequately respond to a stimulus that is lower than the stimulation threshold of the C fibres (Olgart, 1974). Vascular supply of the dental pulp The maxillary artery supplies the dental pulp. The maxillary artery is composed of small arteries and enters the dental pulp via the apical foramen, as well as through accessory foramina. When the small vessels branch from the central arteriole, they form a network of capillaries (Takahashi, 1985). The formed network of capillaries does not enter the dentinal tubules but moves towards the dental pulp (Takahashi, 1985). The sub-ondontoblastic zone comprises of about 90% of pulpal capillaries, and it is used to provide nutrients to the highly specialised dentin-forming cells. The venules that are connected to the central pulpal venules help in drainage. There are other shunt vessels that are found within the dental pulp. However, their role in the dental pulp is unknown (Kim et al., 1983; Takahashi et al., 1982), although there are suggestions that the shunts are used in maintaining the flow of blood in the pulp (Kim et al., 1984). The diseased dental pulp The duration and type of irritation of the dental pulp determines how the pulp reacts to harmful stimuli. For example, an acute response can be induced in the case of a short-term irritation. During such cases, the inflammatory pro cess can be reversed by removing the irritant.Advertising Looking for critical writing on dentistry? Let's see if we can help you! Get your first paper with 15% OFF Learn More On the other hand, chronic pulpal inflammation is experienced following long†term dental pulp irritation, which might result from harsh chemical substances, cracks, tooth surface loss, leaking restorations, and dental caries. The roots of teeth mature in stages, which might determine the pulpal response to stimulation (Cvek et al., 1990; Kling et al., 1986). Age related changes in the dental pulp The dental pulp of any individual undergoes different changes as the person ages, (Morse, 1991). Such changes can include root canal calcification, arteriosclerosis, diminished blood supply, and dystrophic mineralisation of the nerve fibres (Bernick, 1967). Pulp testing of teeth Indications According to a review of literature, understanding the state of health of one’s dental pulp is very important (Noblett et al., 1996). For instance, in the light of Ehrmann (1977), vitality tests form the basis of mouth examination. As such, pulp testing of teeth can be carried in case of th e following: Prior to undertaking definitive operative procedures on teeth A lot of effort has been put on the fact that there can be degenerative pulpal changes on a tooth despite the lack of clinical symptoms or even other radiographic symptoms (Kramer, 1954). In addition, radiographic examination may fail to indicate the loss of cancerous bone (Bender, 1982). For this reason, it is important to carry out pulp tests to find out the actual state of health of the concerned tooth before carrying out any form of treatment (Ehrmann, 1977). Such considerations help to prevent complications in the future. Diagnosis of pain Most examinations on dental treatment have showed that orofacial pain is common among dental patients (Ehrmann, 1977). In spite of this, research and analysis in the UK, indicated that the prevalence of orofacial pain, without consideration of headache, of non†dental origin accounts for 7%, with some of these cases, including chronic pain from other parts of the body (Zakrzewska, 2007). For this reason, it becomes challenging especially in the localisation and diagnosis of pain. Therefore, effective diagnosis of pain in the trigeminal area can be done through pulp tests (Mumford, 1976; Mumford Bjorn, 1962). In addition, pulp testing can be used to differentiate between pain of pulpal origin from that of non†dental origin, as evident in myofacial pain dysfunction syndrome (Duquette Goebelm, 1973) and referred pain (Harris, 1971). For the source of pain to be confirmed, there is a need for pulp degeneration signs. In a case whereby the concerned tooth has undergone root canal treatment, it is advisable to look out for an extra sign despite (Ehrmann, 2002). Investigation of radiolucent areas In the diagnosis, as well as in the treatment of disorders in teeth, pulp testers are very important (Hare, 1969; Harris, 1971; Klein, 1978). For example, through effective application of pulp testers, apical extension of pulpal pathos may be exclu ded. After successful exclusion, attention can be focussed on discrimination of any other pathological processes (Harris, 1971; Harris, 1973). Assessment of teeth following dental trauma Monitoring of tooth vitality is important in traumatic dental incidents. Such significance is attributable to the fact that some teeth may take several months to respond to pulp testing (Olgart et al., 1988). In addition, assessing the state of health of the dental pulp, or pulp vitality, helps in the identification of any form of treatment that needs to be carried out on the affected teeth (Roed†Petersen Andreasen, 1970), as well as those undergoing surgical trauma. Trauma in this case, can include transplantation procedures (Urbanska Mumford, 1980), or even sub apical osteotomy (Johnson and Hinds 1969). Assessment of teeth that have undergone pulp preservation procedures or have required deep restorations In dental treatment, it is important to confirm the state of the pulpal health from t ime to time especially for teeth that have undergone extensive restorations or pulp preservation procedures (Cvek, 1978). Pulp tests can be used to primarily indicate the treatment outcome (Dummer et al., 1980; Seltzer et al., 1963). Evidently, determining the state of the pulp ought to be done early enough to avoid failure of the treatment. If detected later, complications might occur that might be expensive to treat with some resulting to under†diagnosis and under†treatment (Tronstad, 1988). Such conditions are highly likely to lead to periradicular periodontitis in abutment teeth (Bergenholtz Nyman, 1984; Petersson et al., 1999). Methods For an ideal pulp testing method, it is important to ensure that the method is simple, objective, standardised, reproducible, non†painful, non†injurious, and accurate. In addition, the method ought to be relatively cheap to allow effective assessment of the pulp tissues (Chambers 1982). Nowadays, there are two wide catego ries of pulp testing methods that can be used in the dental practice. These categories are the pulp vitality and pulp sensibility testers. Pulp sensibility tests Pulp sensitivity testers are subdivided into thermal and electric pulp testers. Sensitivity, in this case refers to the ability to feel or perceive sensation. Electric and thermal stimuli are used in pulp sensibility testers. Such stimulus is useful in direct assessment of how the AÃŽ ´ sensory nerve fibres are reliable within the pulp dentine complex, as well as in indirect determination of the state of pulpal health. In a case of positive response, such a stimulus shows that there is a possible nerve supply within the dental pulp, while on a secondarily level; it shows that there are vital pulp tissues. This assumption is considered true because the AÃŽ ´ nerve fibres have a very high sensitivity to hypoxia. Therefore, these fibres can and thus lose reliability in cases of pulp tissue degeneration (Edwall Kindlova, 1971) . Types of tests and mechanisms of action Thermal pulp testing Cold and hot agents can been used in thermal pulp testing, with a variety of cold agents being common nowadays. The agents of thermal pulp testing are used in inducing contraction, which is accompanied by dentinal fluid flow outwardly (Brannstrom, 1986). With respect to the hydrodynamic theory, dentinal fluid generates forces that tend affect the micro-receptors of the AÃŽ ´ nerve fibres eliciting a form of sensation that ends when the stimulus is removed (Trowbridge et al., 1980). Nevertheless, cold testing agents have different boiling points, an implication that a considerable reduction of temperature is witnessed whenever the agents are used. Ethyl chloride is an example of cold testing agent that is frequently used in pulp tests, and has a boiling point of †4 °C. Other agents such as dichlorodifluoromethane, carbon dioxide, and non-chlorofluorocarbon are also used in thermal pulp testing (Pitt Ford Patel, 2 004). However, there are other agents, such as ice-sticks, that are used in cold†testing [Figure 3], and bathing the tooth with cold water after isolating it with a rubber dam (Pitt Ford and Patel 2004) [Figure 4]. Gutta-percha points [Figure 5]; bathing the affected tooth with hot water [Figure 6], can be used in pulp testing. However, the gutta-percha method is no longer used because it is difficult to control temperatures and can lead to overheating of the teeth (Narhi 1985), or pulpal damage (Mumford 1964). Figure 2: Cotton pledget sprayed with a refrigerant agent. Figure 3: Pulp testing of a tooth using ice†sticks Figure 4: Pulp testing of a tooth using a cold water bath following rubber dam isolation Figure 5: Pulp testing of a tooth using heated gutta-percha Figure 6: Pulp testing of a tooth using frictional heat generated by a rotating rubber cup. Electric pulp testing An instrument that runs on battery is used to perform electric pulp testing. The instrumen t is used to provide electrical current to the crown of the affected tooth [Figure 7]. A labial hook is used to complete the electric circuit [Figure 8]. However, for the process to be effective, and for maximum current transmission there needs to be a conductive medium between the point of treatment and the tip of the electric pulp tester (Cooley Robison, 1980; Michelson et al., 1975). Once an electric current is initiated, an action potential is generated that is followed by the depolarization occurring within the dentinal fluid (Pantera et al., 1993). Figure 7: Pulp testing of a tooth using an electric pulp tester Figure 8: Electric pulp testing of an upper right central incisor isolated from adjacent teeth by rubber dam strips. General limitations of pulp sensibility testing methods Even though pulp sensibility testers may not comply with all the features of an ideal testing method, they can be quite effective if properly applied. However, it is important to consider the foll owing limitations: Assessing nerve viability rather than pulp vitality One of the first steps of assessing the state of the dental pulp health is to examine the flow of blood within the dental pulp (Bhaskar Rappaport, 1973; Chambers 1982; Fratkin et al., 1999). As such, the ‘pulp vitality tester’ has the implication of an analytic method with the capability to directly assess the vascularity of the dental pulp. On the other hand, pulp sensibility tests can be used in determining whether or not a nerve supply is reactive (Bhaskar Rappaport, 1973; Ehrmann, 1977; Johnson Hinds, 1969). In most of the cases, pulp sensitivity tests are considered as proxy markers (Ikeda Suda, 1998; Yanpiset et al., 2001). However, thermal and electrical tests often give false responses, thus making tests unreliable in the case of damage on the pulp vasculature (Radhakrishnan et al., 2002). Lack of correlation with the histological condition of the dental pulp Findings from studies on several pulp testing methods do not show any correlation when compared with the history of the dental pulp (Barker and Ehrmann 1969; Lundy and Stanley 1969; Marshall 1979; Matthews et al. 1974; Mumford 1967). Nevertheless, a significant relationship has been identified between necrotic pulp tissues and the negative responses observed during pulp testing (Lundy Stanley, 1969; Marshall 1979; Seltzer et al., 1963). Lack of objectivity There has been a lot of debate on the role of an individual’s response to pulp sensitivity, with some scholars pointing out that such response is very objective (Ingle Beveridge, 1976), and others disagreeing with reasons based on the nature of pain (Degering, 1962; Ehrmann, 1977; Stark et al., 1977). However, such misunderstanding can be overcome by setting up a control tooth during the testing process (Chilton Fertig, 1972). In spite of this, the control tooth may not be useful in the event of a wrong and inaccurate method (Seltzer et al., 1 963). In addition, the degree of neural response does not necessary imply that there is a pathological condition (Mumford, 1976). Lack of reproducibility Research and analysis in dental practice has showed that different individuals respond differently to pulp tests, depending on the days, and time of the day, which is attributable to the diverse emotional conditions among patients (Grossman, 1978). In addition, available types of electric pulp testers have different degree of accuracy (Cooley Robison, 1980; Matthews et al., 1974). Unpleasant sensation The stimulation of the pulpal nerves pulpal sensibility testing, elicits individuals to respond differently. Several researchers have showed that stimulation of the pulpal nerves leads to pain (Naylor, 1964; Greenwood, 1973). On the other hand, other researchers have countered such proposition arguing that there are several instances patients get different sensations other than pain (Mumford Newton, 1969). In spite of such argum ents, the sensation that an individual experience as a result of pulpal stimulation is often unpleasant. In addition, this unpleasant sensation often establishes a premature response on the affected patient (Cooley Robison, 1980). Effect of distribution of teeth in the oral cavity Multi-rooted teeth have often been hard to assess the state of their pulpal health as compared to single†rooted teeth. There is a high possibility of positive response for a tooth that has vital pulps as opposed to neurotic pulps (Peters et al., 1994). Effect of maturation status of the tooth During the early development of teeth up to about 5 years, there is incomplete neural supply within the dental pulp (Bernick 1969). Theoretically, during such development stages, it is of no use to carry out pulp sensitivity tests. This can be attributed to the fact that pulp sensitivity tests on immature teeth often register no response (Klein 1978) to positive response, but shows a negative high value whe n using the EPT (Dummer et al., 1980; Grossman, 1978). However, according to a study carried out by Fulling and Andreasen (1976), the EPT recorded no response for immature canines, while a response was observed for other teeth at a higher threshold value. As such, there was an inverse relation between the threshold value and the degree of tooth maturation. In addition, it was evident that for immature teeth, carbon dioxide was a better substitute for EPT (Fulling Andreasen, 1976). Effect of tooth condition When assessing the state of health of the dental pulp for a tooth that was restored by covering the crowns with a metal, carbon dioxide is better testing agent (Trope Sigurdsson, 1998). In addition, the clinician can consider the use of dental instruments like sickle probes, in cases where there is fear of contact with gingival tissues, as well as when there is a need to avoid subsequent false†positive responses (Pantera et al., 1992). Effect of trauma Dental pulp bloo d vessels are more resistant to damage than the pulpal nerves (Bhaskar Rappaport, 1973). During dental treatment, the neural undergoes temporary disruption, which can recover within a period of six months (Zadik et al., 1979). For this reason, it is unreliable to use pulp sensitivity testers in the assessment of the state of pulpal health of teeth, because the process is accompanied by traumatic dental injuries (Bhaskar Rappaport, 1973; Ehrmann, 1977; Teitler et al., 1972; Zadik et al., 1979). Effect of orthodontic treatment There are numerous changes that occur during pulp sensibility testing of orthodontically treated teeth (Hamersky et al., 1980). For this reason, the results from such a procedure cannot be relied upon (Burnside et al., 1974; Hall Freer, 1998). Orthodontically treated teeth have showed characteristics of responding to electrical pulp testers at a high threshold of about nine months (Cave et al., 2002). As such, better agents such as carbon dioxide can be use d in such cases to assess the state of pulpal health (Cave et al., 2002). Pulp vitality tests Early stages within the dental pulp have been cited to play a major role in pulpal inflammations (Baumgardner et al., 1996; Kim, 1990). For example, the flow of the blood within the dental pulp provides oxygen and nutrients to the dental pulp. As such, if the flow of blood is altered, the rate at which the pulp gets oxygen and other important nutrients is interfered with. As such, the flow of blood within the dental pulp is a very important aspect of the pulp. Thus, whereas the use of pulp sensibility testers is very important in the provision of significant information about dental diagnosis, it is important to assess the state of vascular supply for proper determination of the pulpal health (Fratkin et al., 1999; Radhakrishnan et al., 2002). 2.2.2.2.1 Types of tests and mechanisms of action There are different methods available nowadays to ascertain the nature of the flow of pulpal blood. Based on their significance, these methods have become common within the dental practice. Some of the commonly used methods are highlighted below: Laser Doppler flowmetry (LDF) The Laser Doppler flowmetry (LDF) method became common within the dental practice in the late eighties, and preferred for its non-invasive characteristics when used in the measurement of the flow of pulpal blood within an individual’s teeth (Gazelius et al., 1988; Gazelius et al., 1986) [Figure 9]. This method use the technology of infra-red beam propagated from a laser source, and directed to the area tooth under investigation. As such the light is allowed to move via the dentinal tubules towards the dental pulp (Matthews Vongsavan, 1993) [Figure 10]. After reaching the dental pulp, red blood cells and other tissues within the pulp absorb the light. In the case of a back-scattered light, Doppler shifting can never occur unless there is an interaction between the circulating red blood cells and photo ns of light. If the interaction occurs, a portion of the light is send back to the photo detector for analysis (Ingolfsson et al., 1994). The output signal is viewed in the form of flux, and a concentration of blood cells (Gazelius et al. 1988; Olgart et al. 1988), as shown in Figure 11. Figure 9: Laser Doppler Flowmeter (LDF) [Moor Instruments, Axminster UK]. Figure 10: Application of LDF probe to the facial surface of a sectioned tooth reveals the passage of light through enamel prisms and dentinal tubules to reach the dental pulp. Figure 11: Signals recorded by LDF. A diagram showing vital tooth is shown by the line at the top; a non†vital tooth appears at the bottom. Laser Doppler Flowmetry has been considered semi-quantitative, objective, reliable, reproducible, and non-invasive when used in the measurement of pulpal blood flow (Gazelius et al., 1988; Gazelius et al., 1986; Olgart et al., 1988; Raab et al., 1988; Ramsay et al., 1991a; Ramsay et al., 1991b; Sasano et al ., 1989; Wilder†Smith, 1988). In spite of such features, there are other factors that may affect the suitability of LDF in measurement of pulpal blood flow. Such variables are outlined below: Laser beam characteristics The bandwidth that is used in any form of dental pulp examination is very important since it influences the flux values. Therefore, clinicians ought to choose the right bandwidth, with a narrow bandwidth of 3.1 KHz being preferred (Roebuck et al., 2000; Odor et al., 1996a; Odor et al., 1996b). On the other hand, the laser source ought to be relatively longer, preferably 810 nm because such a length allows in-depth penetration of the pulpal vasculature (Odor et al., 1996a; Odor et al., 1996b). Probe position and non†pulpal signals In cases where the probe was next to the gingival margin, several studies indicated high flux values (Hartmann et al., 1996; Ramsay et al., 1991a), which is attributed to a continuous flow of blood signals within the non-pulpa l tissues that are close to the probe. Some of these tissues include the tongue, lips, the periodontium, and gingival tissues (Hartmann et al., 1996; Ikawa et al., 1999; Polat et al., 2004; Polat et al., 2005; Soo†ampon et al., 2003; Vongsavan Matthews, 1993). The ideal distance from the gingival margin should be 2†3 mm, as such a distance minimises the contamination of signal. In addition, such a distance minimises signal noise, and is suitable in the provision of an output that is recognizable (Roebuck et al., 2000; Vongsavan Matthews, 1996). In other cases, reduction of the signals recorded can be achieved through a considerable isolation of the affected tooth by the use of an opaque rubber dam, which may also apply to cases involving vital teeth (Soo†ampon et al., 2003; Kijsamanmith et al., 2011). Probe design The optical separation distance is used to determine the probe design, and has a significant effect on the recorded signal. In addition, the separati on distance is very useful in determining the concentration and flux values of the recorded signal (Roeykens et al., 1999). Probe holder characteristics A flux artefact is produced as a result of loud sounds, and extraneous noises (Musselwhite et al., 1997; Mesaros Trope, 1997). Such artefacts can be reduced by the use of opaque putty (Mesaros Trope, 1997). Tooth type Sasano et al. (2005) showed that LDF was unreliable in getting signals in cases involving from thicker teeth, through the use of a low-power laser beam. From this study, it was evident that the thick layer around the teeth’s dentition prevents photons from penetrating deeply into the pulp tissues (Sasano et al., 2005). Tooth surface imperfections and discolouration The surface of the tooth can have several imperfections such as cracks (Hartmann et al., 1996), as well as light†absorbing pigments (Heithersay Hirsch, 1993). Such imperfections tend to interfere with the signal output. Use of medicati ons Factors such as the use of anaesthetic agents (Chng et al., 1996), neurogenic mediators (Olgart et al., 1989), vasoactive substances (Okabe et al., 1989), and smoking (Johnson et al., 1993) influence the recorder signal significantly. Pulse Oximetry (PO) Pulse Oximetry (PO) refers to a non†invasive and objective method that is used in the measurement of the level of oxygen saturation in the blood. It uses a photo detector to identify the amount of oxygen absorbed, as well as calculates the saturation level of the absorbed oxygen (Noblett et al., 1996; Raab et al., 1988; Schnettler Wallace, 1991). Transmitted light photoplethysmography (TLP) This method is used in the assessment of the flow of blood within the dental pulp of humans, as well as of animals (Daley et al., 1988; Miwa et al., 2002; Lindberg et al., 1991). Dual wavelength spectrophotometry (DWLS) Dual wavelength spectrophotometry, commonly abbreviated as DWLS, is an example of non†invasive technique that makes use of a fibre optic probe in the transmission of visible light of dual wavelengths (760 and 850 nm) (Nissan et al. 1992), in the assessment of whether or not there is any oxygenated blood. There are hopes that DWLS will be useful in the future as a pulp testing method (Nissan et al. 1992). Thermography and tooth surface measurement techniques Studies have showed that teeth that have a healthy supply of blood have warmer surfaces as compared to those that have a degenerated blood supply. Such a condition explain why thermo-graphic imaging are used in the measurement of blood flow in the dental pulp (Pogrel et al., 1989; Kells et al., 2000b; Kells et al., 2000a). For instance, electric thermometers that can be attached onto the dental probes (Fanibunda, 1986b; Fanibunda, 1986a), as well as liquid crystals with the ability to give different colours when subjected to heat are examples of tooth†surface measurement techniques (Howell et al., 1970). Limitations of pulp vitalit y testing methods There are several limitations of using pulp sensitivity testers. However, most of these limitations do not apply in the case of pulp vitality testers. For example, the methods used in pulp vitality testing are often objective. For this reason, the need to assess a patient’s response is eliminated, which has been considered to be a source of errors especially when examining children, as well as disabled patients. In addition, research and analysis has showed that pulp vitality testers do not inflict any pain on the patient, and that they are non-invasive. In spite of this, there are a few limitations that are associated with pulp vitality testers. For example, they use highly complex thermo-graphic imaging technique (Kells et al., 2000b). Similarly, these testers require clinicians to adhere to the technique for pulp vitality testers as in PO, failure to which it becomes impossible to obtain reliable results. In addition, conformity is necessary when using pu lp vitality testers because the size of the teeth must be in line with the size of the photo detector sensor used, as well as the size of the anatomical contour. In addition, it is important to ensure that the photo detector and the light†emitting probe are strategically placed (Vaghela Sinha, 2011). According to earlier discussion (section 2.2.2.2.1.1), it was observed that LDF can change with respect to light and movement. For this reason, an opaque putty order is necessary to avoid the effect of sunlight and movement on the LDF. For example, when investigating LDF, PO, or TLP next to a gingival margin, there are high chances of errors due to the effect of external signals. Nevertheless, signal contamination is low in TLP as opposed to LDF (Miwa et al., 2002). Therefore, the ideal distance from the gingival margin should be 2†3 mm since such a distance minimises the contamination of signal. However, pulp vitality testers are not suitable for use in the assessment of t he pulpal health for teeth that underwent heavy heavily restorations and crowning. In addition, such methods are not reliable in assessing the state of the pulpal health of teeth with vital apical pulps. This critical writing on Dental Pulp was written and submitted by user Emiliano Gould to help you with your own studies. You are free to use it for research and reference purposes in order to write your own paper; however, you must cite it accordingly. You can donate your paper here.

Constructing a Deductive Theory

Constructing a Deductive Theory There are two approaches to constructing a theory: deductive theory construction and inductive theory construction. Deductive theory construction takes place during deductive reasoning in the hypothesis-testing phase of research. Process The process of developing a deductive theory is not always as simple and straightforward as the following; however, the process generally involves the following steps: Specify the topic.Specify the range of phenomena your theory addresses. Will it apply to all of human social life, only U.S. citizens, only middle-class Hispanics, or what?Identify and specify your major concepts and variables.Find out what is known about the relationships among those variables.Reason logically from those relationships to the specific topic you are studying. Pick a Topic of Interest The first step in constructing a deductive theory is picking a topic that interests you. It can be very broad or very specific but should be something that you are trying to understand or explain. Then, identify what the range of phenomena is that you are examining. Are you looking at human social life across the globe, only women in the United States, only poor, sick children in Haiti, etc? Take Inventory   The next step is to take inventory of what is already known about that topic or what is thought about it. This includes learning what other scholars have said about it as well as writing down your own observations and ideas. This is the point in the research process where you will likely spend a great deal of time in the library reading scholarly literature on the topic and devising a literature review. During this process, you will likely notice patterns discovered by prior scholars. For example, if you are looking at views on abortion, religious and political factors will stand out as important predictors in many of the previous studies you come across. Next Steps After you’ve examined the previous research conducted on your topic, you are ready to construct your own theory. What is it that you believe you will find during your research? Once you develop your theories and hypotheses, it is time to test them in the data collection and analysis phase of your research. References Babbie, E. (2001). The Practice of Social Research: 9th Edition. Belmont, CA: Wadsworth Thomson.

Assignment Example | Topics and Well Written Essays - 1500 words - 2

Assignment Example One of the main technological advancements that completely transformed the business world is the invention of the Social Media Networks such as Facebook, Skype and Twitter. Technology enables people to network easily, chat and meet friends over the internet. In addition, businesses take advantage of this platform provided by social media networks to advertise their products and services, i.e. through e marketing and e-commerce. Social media networks have millions of people converging on their sites at the same time. Businesses are looking for these customers. Therefore, it is mandatory for every business to have a presence in social media in order to keep adrift with business trends and transformation (Hair, Lamb and McDaniel 14). On the other hand, social media networks also brought about significant transformation in the social-cultural arena whereby it transformed how people interacted. Through social media networks, it is possible for people to meet and make friends with other fr om parts of the globe. Furthermore, social media sites also enable people to participate in online conversations, voice their opinions about certain issues, as well as contribute to both educational and motivational blogs. As such, social communication greatly advanced through social media networks. This greatly improved interpersonal skills and modes of communication across the globe. The world has become a more social place thanks to social media, and social media networks enabled people to marshal support and fight champion for a common course, e.g. social media sites was very fundamental in organizing the Arab Uprising in Egypt in 2011 (Hair, Lamb and McDaniel 14). A recent study by a consumer health organization, Families USA, reported that pharmaceutical drug companies spend over $57 billion per year on promotion. Direct-to-physician activities accounted for the bulk of spending, on a practice called, â€Å"detailing†Ã¢â‚¬â€visits to physicians by pharmaceutical sales representatives in order to promote their firm’s drugs. Free drug samples distributed during these visit represent another significant expense. It is estimated that in total pharmaceutical companies spend over $61,000 in â€Å"promotion per physician†. The other major piece of the marketing ‘pie’ is spent on consumer-direct marketing—ads that suggest consumers ‘ask the doctor† about drugs we may not even need for ailments we may not even have. The report also states that each of the top 10 pharmaceutical companies spend more than twice as much on marketing on research and development. The market for prescription drugs is unique in many ways. Prescription drug marketers must convince a third party-- a physician-- to prescribe their product to the ultimate consumer, the patient. The decider is the physician, and drug manufacturers' promotional efforts traditionally have been directed toward physicians. Furthermore, drug firms increasingly have to influence committees in hospitals and health management organizations who are determining which drugs their physicians can prescribe. (15) (About 250-300 words) If prescription drugs can only be ordered by a physician, what is the purpose of marketing directly

Journal 2 Essay Example | Topics and Well Written Essays - 250 words - 3

Journal 2 - Essay Example Nonetheless, this essay aims at analyzing ethical discrimination. In most cases society have some stereotyping behaviors and they apply or use to discriminate against others in the society. For instance, the study carried out by Dr. Sinikka Elliott, a professor of sociology from North Carolina State University, shows stereotyping in the sexuality of teenage girls and boys by their parents (North Carolina State University 01). From the study, Elliott notes that parents of these set of boys and girls do not believe that their child know or have sexual desires. However, as per report, parents who think that there teenage children may have such feeling, state that their children may be driven to such actions by opposite sex children from other families. This notion is not appropriate for the cohesiveness in the society were members of the society set blames on each other. Therefore, for this case, parents must accept sexuality of their teenage children and learn ways of teaching them on the same rather than blaming the same of teenage children from ot her families thereby leading to discrimination in the society. North Carolina State University (2010, May 4). My kid wouldnt do that: Study shows parents difficulty with teen sexuality. ScienceDaily. Retrieved December 8, 2013, web

LOVE Individual privacy vs. national security Essay

LOVE Individual privacy vs. national security - Essay Example The project will therefore utilize findings from the country to establish the severity of the issues on a global scale. Due to its scope and importance, the project will be conducted using primary sources such as journals, reports from various agencies and newspaper articles. Scholarly articles required in this project will be obtained from the library while relevant reports will be obtained from the concerned agencies. Compromise of individual privacy in pursuit of national security existed before the September 11, attacks. At the heights of World War II, nearly 12,000 Japanese Americans were forced into concentration camps for reasons related to national security (ACLU, 2001). According to Avery (2004), the public feels that issues of national security compromise their privacy. Previous research findings on the issue have proved that intensification of surveillance by security agencies hamper formation of close relationships among people (Emanuel, 2004). To enhance security, the government has authorized all telecom operators in the country to install systems that enable government agencies to access private communications. These preliminary findings will direct the research project. Gross, E. (2004). The struggle of a democracy against terrorism—Protection of human rights: The right to privacy versus the national interest—The proper balance, Cornell International Law Journal 37 (1),

Synthesis and Optical Characteristics of AgO Thin Films

Synthesis and Optical Characteristics of AgO Thin Films Synthesis and Optical Characteristics of AgO thin films Fabricated by Chemical Bath Deposition Method 1EZENWA I. A., 2OBIAGAUZO P. O. 3EBEH L. N. ABSTRACT Binary thin films of silver oxide using chemical Bath method (CBD) have been grown and characterized. Absorbance spectral data of the films were obtained using a Shimadzu 1800 UV- VIS spectrophotometer. An Olympus optical microscope at 100X magnification was used to examine and produce micrograph of the grown thin, which showed that the films have crystal structure and have small grain sizes. A bandgap of 1.62eV and a refractive index range of 1.1- 2.31were obtained. INTRODUCTION Binary thin films are thin films that contain exactly two different elements. Binary thin film had been grown and characterized by many researchers for various applications, examples are; Ag2S (Ezenwa et al., 2012), FeS (Uhuegbu, 1989), ZnS (Ndukwe 1999), Ag4O3, (Bielmann et al, 2002), Silver being multivalent, have various phases like Ag2O, AgO, Ag3O4, Ag4O3, and Ag2O3 by interacting with oxygen (Bielmann, Scheallar, Ruffieux, Groning, Schlapbach, 2002).These oxides have different crystalline structures leading to a variety of physiochemical, electrochemical, electronic and optical properties. The most observable and stable phases are Ag2O and AgO (Garner and Reeves, 1954). Ag2O thin films have been widely studied due to their wide range of applications. The recent interest in silver oxide is for its potential use in optical memories. Photoactivation of silver oxide leads to nanosilver clusters (Hou, Ouyang, Chen et al 1998).These nanoclusters emit fluorescence and also exhibit plas monic behavior. These properties have a wide application range from ultra high density optical data storage to plasmon photonic devices (Tominaga, 2002).They are also used as a sensor for gas detection and photovoltaic materials, studies have shown that silver oxide films have a wide range of energy band gap of between 1.2 and 3.4eV(Dierson, Rousselot, 2005). The major routes used for silver oxide films deposition are reactive sputtering of silver metal in an oxygen-containing argon atmosphere and electron-beam evaporation of silver metal. Another method is the pulsed laser deposition technique (Raju, Kumar, 2011),this method takes place in gaseous phase, hence requiring high temperatures. These high temperature methods also limit the type of substrates used in high temperature resistant substrates. Alternatively wet chemistry and electrochemical methods have been used as low temperature method.Wet chemistry methods generally require the substrates to be dipped inside the precursor solution for days to form thin film materials at temperatures of up to 200Â °C, while electrochemical deposition grows thin film materials on conductive substrate at lower temperatures (

Comparing Prince Hal and Henrys Models of Statescraft :: essays research papers

Comparing Prince Hal and Henry's Models of Statescraft To compare the difference between King Henry and Prince Hal's style of statecraft, first we have to understand the basic philosophy of each. The King belives that to effectively lead the country one needs to lead by example. According to the King's philosophy the best man is the one who lives a pure life and garners respect and honor from all men. To the King's way of thinking Hotspur is more fit to be a King than Prince Hal, a comparison the King makes several times. In Act I, scene i King Henry makes his first comparison of Hotspur to his son saying that Lord Northumberland's son, Hotspur, was "A son who is the theme of honour's tounge..." while Prince Hal was stained by "...riot and dishonor...." In fact the King goes so far as to wish that Hotspur was his his son and not Prince Henry. Later in Act III, scene ii King Henry tells the Prince that Hal reminds him of the way King Richard acted before Henry took the throne and that Hotspur reminds the King of himself. This is the King's not so subtle way oftelling Hal that the King doesn't think he is fit to suceed him to the throne. Prince Hal on the other hand has a different idea of statecraft. He expresses his ideas in his speech in Act I, scene ii when he says "If all the year were playing holidays, To sport would be as tedious as to work; But when they seldom come, they wish'd-for come,...My reformation glitt'ring o'er my fault, Shall show more goodly and attract more eyes than that which hath no foil to set it off." He is saying that he may be acting like a common ruffian now but when he does take up his duties as heir to the throne and begin to act like a prince he will shine more in the eyes of men because his actions now will provide a contrast by which they can judge him. It is important to note that Hal does not plan to spend the rest of his life acting in this manner. He does plan to leave this life behind and take on the role of heir apparent to the throne of England. In Act III, scene ii when the King confronts Hal about his delinquencies Hal is quick to agree with the King. He admits that he has not acted the part of a prince and humbled by the condemnation of the King swears a vow to redeem

Hate Hurts, How Children Learn and Unlearn Prejudice

You know there is hate and prejudice out there in the world, but sometimes you try to live your life pretending it’s not, just as long as it is not affection you or your family. It was surprising to me to see how early children notice differences in each other. Even children are already using (race) in some rudimentary way at six months (Stern, Larosa pg. 18). It’s amazing to hear about Dr. Phyllis Katz’s experiment. We know babies pay attention to their surroundings, and the people in it. Just didn’t realize how closely. In her experiment it showed how a six month old baby got bored looking at the same pictures of the same faces, and then got interested when a face of a different color was introduced. These differences help babies form a secure knowledge of themselves as entities separate from others (Stern, Larosa pg 18). I was very shocked by how ignorant one parent was about prejudice. She says â€Å"It’s something I thought he didn’t notice†¦ that wouldn’t be part of his consciousness†¦ I sort of wanted him to be colorblind. † Clearly children are NOT color – blind. Unless they are taught to appreciate differences, their views can be quite early (Stern, Larosa pg. 27). With teenagers things get a little harder. They are torn between being a child and a young adult. You want to be sure they are not doing things they shouldn’t, but you don’t want to pry into their lives too much. They are trying to be independent from you, and do and make their own decisions. Parents of teenagers in our society must learn to listen to what their offspring are saying, especially what they are saying to one another (Stern, Larosa pg. 9). This book gives you so many heart breaking examples of how children have treated other children so wrong with hatred and prejudice. It also has given examples of how these children over came those hardships; it just would have been nice to hear more of the good instead of the bad. After reading this book, it makes you wake up and realize you can’t live your life as if hate and prejudice isn’t out there. We as a society must teach our children that differences should ot be a threat, but that differences are what make the world go around. It seems that hate and prejudice has plagued our country for the entirety of it’s existence. You can go back and look in history books and find it almost any where in history. This is an issue that bears much consideration because it is not going away by itself. We were created equal in the sight of God, and when everyone recognizes that to be fact and teaches their children, then maybe we will be well on our way to a peaceful existence.

People Management and Organisation Development The WritePass Journal

People Management and Organisation Development Executive Summary People Management and Organisation Development . Strategic Organisational Communication: In a Global Economy. Hoboken: John Wiley Sons. Cummings, T. and Worley, C., 2014. Organisation Development and Change. Belmont: Cengage Learning. Fairholm, M., 2009. Leadership and Organisational Strategy. The Innovation Journal: The Public Sector Innovation Journal, 14(1), pp.1-16. Freedman, A., 2011. Using Action Learning for Organisation Development and Change. OD Practitioner, 43(2), pp.7-13. Griffin, R. and Moorhead, G., 2009. Organisational Behavior: Managing People and Organisations. 9th ed. Belmont: Cengage Learning. Hashim, M., 2014. Organisational change: case study of GM (General Motors). Journal of Business Administration and Management Sciences Research, 3(1), pp.1-5. Hendrickson, S. and Gray, E., 2012. Legitimizing Resistance to Organisational Change: A Social Work Social Justice Perspective. International Journal of Humanities and Social Science, 2(5), pp.50-59. Griffith-Cooper, B. and King, K., 2007. The partnership between project management and organisational change: integrating change management with change leadership. Performance Improvement, 46(1), pp.14-20. Idris, K., Adekalu, S. and Genty, K., 2014. Organisation Development and Strategic Intervention for Enterprise Sustainability: Empirical Evidence from Nigeria. British Journal of Arts and Social Sciences, 16(11), pp.156-171. Kaplan, R. and Norton, D., 2001. Building a Strategy – Focused Organisation. Ivey Business Journal, May/June 2001. Available at http://iveybusinessjournal.com/topics/leadership/building-a-strategy-focused-organisation#.VGS9rWdqRIh [Accessed 12 November 2014]. Kotter, J. and Schlesinger, L., 2008. Choosing Strategies for Change. Harvard Business Review, July/ August 2008, pp.1-10. Lunenburg, F., 2010. Organisational Development: Implementing Planned Change. International Journal of Management, Business and Administration, 13(1), pp.1-9. Oswick, C., 2013. Reflections: OD or Not OD that is the Question! A Constructivists Thoughts on the Changing Nature of Change. Journal of Change Management, 13(4), pp.371-381. Maimunah, I., 2009. Corporate Social Responsibility and its role in community development: An international perspective. The Journal of International Social Research, 2(9), pp.200-209. Nordin, E., 2014. Communicating Organisational Change: Strategies for Communicating Change. The Clute Institute. International Academic Conference, San Antonio, Texas, USA, pp.135-145. Available at http://cluteinstitute.com/conference-proceedings/2014SAPapers/Article%20236.pdf. [Accessed 12 November 2014]. Pasmore, W., Woodman, R., Noumair, D. and Shani, A., 2013. Research in Organisational Change and Development. Bingley: Emerald Group Publishing. Roberts, G., 2014. Servant Leader Human Resource Management: A Moral and Spiritual Perspective. New York: Palgrave Macmillan. Rothwell, W., Stavros, J., Sullivan, R. and Sullivan, A., 2009. Practicing Organisation Development: A Guide for Leading Change. 3rd ed. Hoboken: John Wiley Sons. Samson, D. and Bevington, T., 2012. Implementing Strategic Change: Managing Processes and Interfaces to Develop a Highly Productive Organisation. London: Kogan Publishers. Schabracq, M., 2009. Changing Organisational Culture: The Change Agents Guidebook. Hoboken: John Wiley and Sons. Wu, M., 2012. Managing Stakeholders: An Integrative Perspective on the Source of Competitive Advantage. Asian Social Science, 8(10), pp.160-172. Yaeger, T. and Sorensen, P., 2009. Strategic Organisation Development: Managing Change for Success. Charlotte: IAP Publishing. Yilmaz, B. and Gunel, O., 2009. The Importance of Strategic Stakeholder Management in Tourism Sector: Research on Probable Applications. TOURISMOS: AN INTERNATIONAL MULTIDISCIPLINARY JOURNAL OF TOURISM, 4(1), pp.97-108.

GATBYS dream essays

GATBY'S dream essays The American Dream, wanted by all, captured by some. Colossal amounts of money, love, fame, and power, only some of the many facets of what most people can only dream of, but only a spare few can actually grasp. In F. Scott Fitzgeralds book, The Great Gatsby, the majority of its characters all embody the American Dream in some way or another, and are continually searching for those previously mentioned attributes of a higher standard of living in a 1920's society. Jay Gatsbys life begins in the search for his personal American Dream and ends in tragedy because of his blindness in focusing so much of his attention to finding love with Daisy. In the beginning, Gatsby is described by nick that he stretched out his arms toward the dark water in a curious way and.... he was trembling... nothing except a single green light. One can relate Gatsbys reaching toward the solitary light far off into the distance, as him reaching toward the last part of his dream. As far as anyone knew, Gatsby had everything, money, friends, stature in society, and fame. But, there is one thing that Gatsby was longing for, which was someone for him to love, and someone to love him. His only problem with his wish was that it had already been granted to another man, although that didnt hinder his efforts to have Daisy for his own. A distant relative of Nick Carraway, Daisy Buchanan, seems to epitomize a major portion of the American Dream. Before our story had begun, Gatsby and Daisy had already met, and Daisy had refused to marry him because of his lack of finances. But later in our story, when Gatsby is showing her his shirts, anyone can clearly see that she has a little regret for marrying Tom instead of Gatsby, because of what she could have had with him later. Daisy could easily be called a Gold-digger, which is actually a part of her dream, to have someone take care of h ...

Museum of Islamic Art Essay Example | Topics and Well Written Essays - 3000 words

Museum of Islamic Art - Essay Example The Museum of Islamic Art, Doha Islamic art and culture goes back 1,400 years ago to the years of the Prophet through to the eras of the Caliphs and Ottoman Empire. Qatar has been known for the oil boom which led to massive and large scale construction works in the country in the past three decades. Many landmark buildings have been built within this period in strategic locations to maintain the unique features of the region. The Museum of Islamic Art (MIA) is located on the south end of the Doha bay and it is a major building located on the edge of the Doha harbor and it has unique and distinct features that makes it a might build that depicts Islamic arts in architecture, usage and construction. Project Initiation and Location The Museum for Islamic Art was designed by the architect, Ioeh Ming Pei who blended Islamic tradition and monumental modernism to create the structure (Ourousoff 31). The project was commenced in 2004 when the Qatari government announced the desire to build a major structure that will reflect Qatar's bid to become the cultural center of the Arab world (Skinner 1). Actual work and construction activities commenced in 2005 and this ultimately led to the completion of the project in 2006. The project reflected Qatar's quest to present itself as one of the most prosperous economies in the Islamic world with the highest gross domestic products per capita in the world (Skinner 1). This was reflected in the magnitude of the project and the resources committed to its completion. The location of the MIA in the city of Doha also makes it an extremely distinct work of engineering because it required a cross-functional role that involved marine engineers aside the normal construction site to ensure that the project remained within reasonable range. The project is located on a newly created Peninsular or man-made island that is protected by a seawall just off the harbor of Doha in the south of the city (Ourousoff 33). The project is meant to blend a set of different elements and present the Qatari nation and the Islamic world on an exceptional pedestal. First of all, the building involved an architecture that reflected elements of Medieval Arabic architecture that incorporated elements of palaces amongst great Arab leaders. Secondly, the building involved important and carefully calibrated to provide exhibitions for various categories of Islamic history and culture. This include the arrangement of exhibition spaces, galleries, library and an auditorium. The venue is meant to exhibit elements of various stages in Islamic history and will display works of art, numismatics, manuscripts and weapons. Socio-Cultural Elements of Qatar & the Islamic World it Depicts The Museum of Islamic Art was a project that was initiated under the auspices of Qatar's hereditary Al-Thani dynasty as an attempt to enhance Qatar's cultural status. To this end, the MIA was meant to bring together the relics, audience and artists to develop the cultural systems and structures of the country for the future (Hudson para 6). Upon deciding to build the museum, the Qatari Museum Authority, headed by Sheikha Mayassa al-Thani called upon the then 86-year old IM Pei to draw the blueprints and architectural plan for the museum (Hudson para 2). The Chinese-American IM Pei was called for retirement to assist in drawing

Shape Security Profile Research Paper Example | Topics and Well Written Essays - 500 words

Shape Security Profile - Research Paper Example Shape Security business strategies include diversification of product line through internal and external funding. For example, in 2014, the company allocated $40 million in funding (Ingrid, 2014). In this way, it was able to expand its products to include website hosting, high-speed internet, domain registration and email hosting among other. Shape Security target customers include banks, firms using ecommerce, healthcare organizations, cyber cafes and individuals using different websites among other users. Given the extensive use of internet globally, the company customer base will increase in future. This implies that by creating a strong promotion and more advertising, the company sales will ultimately increase. As the need for marketing in order to expand the customer base increases, firms have noted the importance of value proposition. For the case of Shape Security, innovation has been the key pillar in its brand improvement (Maranville, 1992). The company value proposition is that automation is at the heart of every botnet. In this way, customers are guaranteed of the value and capability of the ShapeShifter in dealing with the attacks. As the competition in the technology industry increases, more firms still are joining the sector due to the high profits enjoyed by firms. ShapeSecurity main competitors include Invincea, Crowdstrike and Defense.net. The enterprise was given the brand name Shape Security in 2011 when it was founded by Sumit Agarwal, Justin Call and Derek Smith. To ensure that potential customers are not confused or fail to differentiate the company brands from those of the competitors, Shape Security has a website- http://shapesecurity.com. The company operations are in line with US IP laws and thus competitors are prevented from producing brands that are the same like those of Shape Security. Shape Security enjoys the support of various investors. For example, Sierra Ventures, Kleiner Perkins Caufield & Byers and