Crowns have been used since the 5th century AD to improve both the form and function of teeth in the mouth. A great proportion of the total expenditure on dental care is spent on the provision and replacement of crowns and bridges and the number is increasing every year. A full coverage crown is a restoration placed over a single prepared tooth or it acts as an abutment in a bridge for the restoration of a missing tooth or teeth. Crowns are considered successful only when they meet both the aesthetic and functional requirements of the patient. For these to be met, certain principles for the preparation of the abutment tooth must be adhered to / such principles include features that are incorporated in the tooth preparation that enable it to withstand the forces of dislodgement that the tooth is exposed to both at rest and function. These features are described as the retention and resistance form of the preparation and the important aspect of these is taper. The taper of a tooth preparation is inversely proportional to the retention provided by the preparation. Volumes have been written on the difficulties encountered in making crowns with an adequate taper. Training, experience and operating conditions are among the many determinants of taper obtained by clinicians. Taper values of 2&ordm / to 5&ordm / were recommended initially for successful crown restorations but over time it was realized that these values were difficult to achieve under clinical conditions without creating undercuts in the preparation. Besides it was shown that even higher taper values might provide adequate retention for crowns. In addition, extra-retentive features such as axial grooves and boxes have been shown to improve retention of crowns. Many of the new luting cements also have adhesive properties that contribute to better retention of crowns and bridges. Various studies have established the prevalent taper obtained by dental students, general practice dentists, residents and prosthodontists while some of these studies have compared the prevalent taper among the different categories of clinicians. None of the studies so far reported has shown the prevalent taper in this environment / all without exception have investigated conditions in Europe, North America and Asia. Aim: This study therefore investigated the prevalent taper obtained routinely under clinical conditions by dental students, general dental practitioners and prosthodontists in two African countries and compared them with the recommended range of 10&ordm / to 22&ordm / . <br /> <br /> Method: 432 dies of teeth prepared by students, general practice dentists, resident and practicing prosthodontists were collected and analysed for taper using the double silicone technique. This involved making silicone replicas of the dies, sectioning these at various points and using photographs of the sections to measure their taper. Comparisons of the tapers obtained were carried out between the students, general practitioners and prosthodontists as well as between taper obtained on the different tooth types. Results: Taper ranging from 2&ordm / to 100&ordm / was obtained on the various tooth types. A mean mesio-distal (MD) and bucco-lingual (BL) taper of 22.5&ordm / (SD 11.2) and 26.2&ordm / (SD 11.1) respectively and a mean overall taper of 24.3&ordm / (SD 9.2) were obtained. Prosthodontists obtained the lowest taper (MD = 20.5&ordm / (SD 10.6)), BL = 24. 5&ordm / (SD 10.1) and a mean overall taper of 22.5&ordm / (SD 8.4). Students were second with a mean MD taper of 23.8&ordm / (SD 10.1), BL taper of 26.1&ordm / (SD 10.9) and a mean overall taper of 25.0&ordm / (SD 8.4). The general practice dentists obtained a mean MD and BL taper of 24.5&ordm / (SD 12.4) and 29.1&ordm / (SD 12.1) respectively and a mean overall taper of 26.8&ordm / (SD 10.6). The lowest taper was seen on premolars while the highest was on molars. Conclusion and recommendation: Most of the preparations analysed had a taper outside the recommended range of 10&ordm / to 22&ordm / . However, these tapers were similar to those found in other studies. Routinely incorporating extra-retentive features into crown preparation designs will improve success of crown restorations and adhesive cements should be used whenever conditions that allow for adequate retention are not met. The importance of taper should be emphasized more in dental schools and tooth preparation support systems should be used for teaching wherever possible. The need for regular refresher courses for practicing dentists and prosthodontists cannot be over-emphasized.

Craniofacial assessment for diagnosis, treatment planning and outcome has traditionally relied on imaging techniques that provide a static image of the facial structure. Objective measures of facial movement are however becoming increasingly important for clinical interventions where surgical repositioning of facial structures can influence soft tissue mobility. These applications include the management of patients with cleft lip, facial nerve palsy and orthognathic surgery. Although technological advances in medical imaging have now enabled three-dimensional (3D) motion scanners to become commercially available their clinical application to date has been limited. Therefore, the aim of this study is to determine normal and abnormal lip shapes during movement for use as a clinical outcome measure using such a scanner. Lip movements were captured from an average population using a 3D motion scanner. Consideration was given to the type of facial movement captured (i.e. verbal or non-verbal) and also the method of feature extraction (i.e. manual or semi-automatic landmarking). Statistical models of appearance (Active Shape Models) were used to convert the video motion sequences into linear data and identify reproducible facial movements via pattern recognition. Average templates of lip movement were created based on the most reproducible lip movements using Geometric Morphometrics (GMM) incorporating Generalised Procrustes Analysis (GPA) and Principal Component Analysis (PCA). Finally lip movement data from a patient group undergoing orthognathic surgery was incorporated into the model and Discriminant Analysis (DA) employed in an attempt to statistically distinguish abnormal lip movement. The results showed that manual landmarking was the preferred method of feature extraction. Verbal facial gestures (i.e. words) were significantly more reproducible/repeatable over time when compared to non-verbal gestures (i.e. facial expressions). It was possible to create average templates of lip movement from the control group, which acted as an outcome measure, and from which abnormalities in movement could be discriminated pre-surgery. These abnormalities were found to normalise post-surgery. The concepts of this study form the basis of analysing facial movement in the clinical context. The methods are transferrable to other patient groups. Specifically, patients undergoing orthognathic surgery have differences in lip shape/movement when compared to an average population. Correcting the position of the basal bones in this group of patients appears to normalise lip mobility.

Endogenous electric fields (EFs) are present during a variety of physiologic and pathologic events, including penetrating injury to epithelial barriers. An applied electric field with strength within the physiologic range can induce directional cell migration of epithelial cells, endothelial cells, fibroblasts, and immune cells suggesting a potential role in controlling cell behaviours during wound healing. Dendritic cells (DCs) and dermal fibroblasts were used to explore the molecular mechanisms underlie EF-induced cell activities during two aspects of wound healing: immune response and remodelling. In this study, we investigated the effects of applied EFs on several types of DCs in response to IL18. DC progenitor cells KG-1 shows dose dependently response to EFs stimulation to increase IFN-γ expression. Moreover, the migration of KG-1-derived DCs and Langerhans cells (LCs) in mouse skin showed increased response to IL18 with directional migration when exposed to EFs in vitro and ex vivo. Furthermore, the in vivo investigation suggested that pharmacologically increased trans-epithelial potential difference (TEPD) induced LCs to emigrate from skin to draining lymph node. The sensitization of DCs to IL18 can be strengthened by EFs through redistribution of IL18 receptors and phosphorylation of p38 MAPK. We also comparatively studied the responses of human chronic wound fibroblast (CWF) and chronic matched fibroblast (CMF) to applied EFs with addition of platelet derived growth factor (PDGF). The results indicate that 1) EFs induce human dermal fibroblast directional migration in a voltage dependent manner. 2) CWF shows impaired sensitivity in response to EFs compared to CMF and HF. 3) Activation of PDGFR and PI3K are both required for EF-induced directional migration. 4) PDGF attenuates EF-induced migration directedness through PDGFR-ROCK other than PI3K pathway. 5) Optimised concentration of PDGF plus physiological EFs enhance chronic wound healing. We propose that the EF-induced re-distribution of the receptors on the cell surface results in a shift of membrane receptors between the cathode-facing and the anode-facing membrane of the cell. There would be a higher probability to overcome the threshold of signal transduction at the higher density receptor side. The downstream IV signalling cascade therefore can be ignited. Understanding the signalling pathways underlying guidance cues (EFs, cytokines, chemokines) will help to optimise future therapies for immunomodulation, vaccination, wound healing and regeneration.

The selection of shade for a porcelain crown is a subjective process and mode of fabrication is known to have an effect. This investigation sought to determine the accuracy of a commercially-available shade-matching device (IdentaColor II) when used to measure the colour of proprietary, custom-made all-ceramic and custom-made metal-ceramic samples of shades B1, A3 and D4 under different calibration and lighting conditions as well as over time. The findings from the first part of the study led to an investigation of the influence of fabrication technique on the colour co-ordinates recorded for the ceramic samples measured previously. Colour measurements were made using a laboratory spectrophotometer, Spectraflash SF600 and were used as a comparator for the IdentaColor II. The reproducibility of these colour measurements was also assessed. The fabrication variables investigated were shade, thickness of ceramic, type of ceramic sample, number of firing cycles, operator, and method of condensation. An attempt was made to determine the correlation between fabrication technique, porosity and colour co-ordinates. The results indicated that IdentaColor II used a measurement system for colour values that conformed to no known standard which made validation difficult. Differences in the colour values were found between different calibration and lighting conditions and over time but these differences were clinically inconsequential. The results from IdentaColor II were reproducible but with limitations: the colours recorded were generally lighter than the chosen standard, there was a preponderance of “A” shades and the device never recorded the intended shade of a sample. The limitations of the colour scale used by IdentaColor II made its further investigation difficult and comparisons with colour-reference standards impossible. The results for the samples which had been measured by IdentaColor II and v Spectraflash SF600 were different: (1) the colour scales used by the two devices were different, (2) the scale used by IdentaColor II had a larger range, (3) the measurements from Spectraflash SF600 were more consistent both within each data set and over time and (4) the trends in the recorded colour co-ordinates when the ceramic thickness increased were different. The colour co-ordinates (C.I.E. L*a*b*) from Spectraflash SF600 for samples ostensibly of the same shade of ceramic were affected by the mode of fabrication which in turn influenced porosity. The colour coordinates generally decreased as the ceramic thickness of metal-ceramic samples of shades B1, A3 and D4 increased and as the amount of pre-sintered slurry condensation increased of metal-ceramic tabs of shades B1 and A3. Metal-ceramic tabs were a closer colour match to the shade tabs than all-ceramic samples of the same thickness.

SAMMANFATTNING Bakgrund: Kunskapen om helkeramiska kronor är begränsad och få studier är gjorda inom allmäntandvård. Syfte: Projektet hade i syfte att undersöka femårsöverlevnaden för helkeramiska kronor samt att utvärdera om patientens kön, typ av porslin, typ av cement, rotfyllnadsstatus och tandposition påverkade överlevnaden. Material och metod: Studien är en retrospektiv journalstudie. Samtliga patienter som under åren 2008-2009 behandlades med en helkeramisk, krona på en kindtand inkluderades, totalt 297 kronor. Kronorna följdes sedan upp i fem år. Resultat: Kronöverlevnaden efter fem år var 91,6 %, ingen skillnad sågs mellan kronor utförda på kvinnor och män eller beroende på typ av porslin och typ av cement. Endokronor hade en något lägre överlevnad, 82,8 %, jämfört med fullkronor, 90,9 % och onlaykronor 100 % (p=0,081). Ingen skillnad sågs i överlevnad beroende på tandposition. Slutsats: Femårsöverlevnaden för keramiska kronor i sidopartier utförda inom allmäntandvården är god Den vanligaste komplikationen, oavsett krontyp, var lossnad krona.

<p><b>Aims and Hypothesis</b>: The objective of this study was the design and testing of a Prototype Computer Numerical Control (CNC) dental handpiece. We predicted that the CNC Prototype would be more accurate than the human participant prosthodontists in clinical simulation. </p><p> <b>Materials and Methods</b>: A Prototype CNC dental handpiece was developed from off the shelf components, assigned 100 typodont teeth (#18) for submission and 10 practice teeth. Single operator. Five prosthodontists, given 20 typodont teeth (#18) for submission and 10 for practice. Finished preparations were scanned with 3M True Definition^&reg; intraoral scanner outside of typodont, compared with Geomagic Control for RMSE. </p><p> <b>Results</b>: RMSE Prototype (N=100) was 0.40mm. RMSE Prosthodontists (N=100) was 0.55mm. One sided T test, mean difference &minus;.15mm (p&lt;.001, one sided CI &minus;.09). One Way ANOVA (F stat &lt;1, F=.526, p=.717), Spearman correlation Prototype RMSE vs order(&rho;=.1, p=.334), RMSE vs Bur (&rho;=.36, p&lt;.001); For each prosthodontist individually (N=20) RMSE vs Order Prosthodontist 4(&rho;=&minus;.54, p= .015). Prosthodontist 5 (&rho;= .58, p = .022). Prosthodontist 3 (&rho;=.16, p=.498), Prosthodontist 2 (&rho;=&minus;.07, p=.772), and Prosthodontist 1 (&rho;=&minus;.08, p=.741) Spearman correlation (N=20) RMSE vs Bur Prosthodontist 5 (&rho;= .51, p = .007), Prosthodontist 2 (&rho;=.46, p= .040), Prosthodontist 4 (&rho;=&minus;.07, p=.758), Prosthodontist 3 (&rho;=.18, p=.445), and Prosthodontist 1 (&rho;=.43, p=.059) </p><p> <b>Conclusion</b>: CNC Prototype achieved superior results in clinical simulation, attained on a modest budget with a modest level of research support. Work should continue on the next iteration of a prototype to address some of the limitations of movement, feedback, and emotional acceptance of a machine performing treatment from the perspective of a patient. </p>

<p> Background: The literature indicates a reduced survival rate for dental implants placed at previously failed sites, smokers, and patients with a history of periodontal disease. The aim of this study is to review the available literature reporting on the success and/or survival of rough surface implants placed at previously failed sites, in smokers, and in periodontally compromised patients. An attempt was made to systematically review the literature and calculate an overall weighted mean survival rate for rough surface implants in each of the above three scenarios. </p><p> Methods: An electronic literature search (MEDLINE-PubMed) was performed and references hand-searched for human studies addressing the success/survival of implants placed at previously failed sites, in smokers and in patients with a history of chronic periodontal disease. The overall weighted mean survival rates and 95% confidence interval were then calculated. Results: Six retrospective studies reporting on implants placed at previously failed sites were included with total of 343 second attempts and 31 third attempts at implant placement at failed sites in 330 patients. The weighted mean survival rates for the second and third attempts at implant placement in a previously failed site were calculated to be 88.05% and 74.19%, respectively. A total of 14,395 implants were included in smoking analysis. Of these, 10,403 implants were placed in non-smokers with 250 failures and 3,992 placed in smokers, with 205 failures. The calculated overall weighted mean implant-level survival was 97.67% in non-smokers and 95.03% for in smokers. Lastly, six studies reported on 591 implants placed in periodontally compromised patients with a total of 15 failures and 198 implants placed in periodontally healthy patients with just one failure. The overall weighted mean implant survival rate was calculated to be 97.48% in periodontally compromised patients compared to 99.49% for periodontally healthy patients. </p><p> Conclusions: Of the three risk factors evaluated in this review, rough surface implants placed in previously failed sites presents the highest risk for implant failure. Rough surface implant survival declines significantly for each additional attempt at implant placement at a previously failed site, with weighted mean survival rates of 88.05% and 74.19% for the second and third attempts, respectively. Although more favorable than previously used implant designs, smokers continue to experience lower survival rates compared to non-smokers, with overall weighted mean implant survival rates of 95.03% and 97.67%, respectively. A similar finding was found for implants placed in patients with a history of chronic periodontitis. The calculated weighted mean survival rate was 99.49% for periodontally healthy patients compared to 97.48% for periodontally compromised patients.</p>

<p> Background: Corticosteroid medications have been researched extensively in oral surgery procedures for the proposed reduction in trismus, swelling, and pain. No consensus has been determined for the most efficacious type, timing, and dosage of medication thus far. In addition little is known about the usage of corticosteroids for periodontal and implant related procedures. The aims of this review are to help clinicians understand the usage of corticosteroid medications in various dental surgeries.</p><p> Methods: The PubMed-MEDLINE and the Cochrane-CENTRAL databases were searched through and up till June 2015 to identify appropriate studies regarding this aim. Appropriate studies were those reporting on the usage of corticosteroids related to its pathophysiology, surgical related outcomes, and patient related outcomes in dental procedures. Conclusions: The search yielded 256 unique papers after selection resulted in 12 publications that met the eligibility criteria. In general the usage of corticosteroids in third molar extractions improved post operatives outcomes related to edema, trismus, and a slight reduction in pain. However, It cannot be recommended to use corticosteroids for pain management. Due to the various types, routes, and dosages of corticosteroid used in studies, no specific drug, route, or dosage can be recommended by literature. The usage of corticosteroids for periodontal and implant related procedures has not been investigated. Further research is required to investigate the possible benefits of corticosteroids on reduction of surgical swelling in periodontal and implant related surgeries.</p>

<p> <i><u>Introduction:</u></i></p><p> Medication related osteonecrosis of the jaw (MRONJ) is exposed bone in the maxillofacial region that does not heal within eight weeks after identification by a health professional. Cancer patients taking or who have a history of taking anti-resorptive or anti-angiogenic agents have an increased risk for MRONJ. MRONJ adversely affects quality of life and results in significant morbidity. It has been shown that patients with risk factors for MRONJ are not aware of the condition or preventive strategies. Understanding patient awareness is the first step in communicating strategies for the prevention of and management of MRONJ.</p><p> <i><u>Aim of the study:</u></i></p><p> To describe the awareness level and characteristics, such as education level, of MRONJ among Roswell Park Cancer Institute (RPCI) patients who receive dental services in the RPCI dental clinic.</p><p> <i><u>Material and Methods:</u></i></p><p> This is a prospective interviewer administered research electronic data capture (REDCap) survey project. The sample include RPCI dental patients who are at least 18 years old with a history of taking, currently taking or will be taking Bisphosphonate, Denosumab, and/or Anti-angiogenic agent as part of their treatment at RPCI and volunteered to participate in the study. Patients were screened for eligibility by an RPCI dentist. Selected patients have been asked 21 questions.</p><p> <i><u>Results:</u></i></p><p> Twenty patients, 10 males and 10 females, participated in this study. The age of our subjects were ranging from 23 to 82 years. Eleven patients have completed a college degree or above, five have completed a high school diploma, and four have some college. Out of 20, nine patients only were aware of osteonecrosis of the jaw (ONJ). No relation has been found between ONJ awareness and gender, education level, or age.</p><p> <i><u>Conclusion:</u></i></p><p> This study shows that awareness of medication-related osteonecrosis of the jaw is poor amongst oncology patients who are at risk of MRONJ. There was no relation between age, gender, or education level and ONJ awareness in oncology patients. An effort to educate users of bisphosphonate, denosumab, bevacizumab, and sunitinib about their medications and their potential side effects as well as including preventative measures must be pursued. Health care providers, especially dentists, must be aware of MRONJ and its risk factors. In addition, they should know the significance of their role in educating and preventing the condition by following their health practice guidelines as well as applying the necessary preventive measures on their patients.</p>

Denture soft lining materials are used as a cushion between the hard denture base and the oral mucosa. Fluid sorption and solubility may contribute to material hardening, roughening, cracking or tearing, loss of adhesion to the hard denture base or contamination by extrinsic stains or yeasts. The ideal material is required to have low fluid uptake, good wettability, retain compliance and surface integrity, and not support fungal growth. Evaluation of behaviour in the oral environment is difficult and a number of materials, such as artificial saliva and food simulating liquids, have been recommended to simulate the environment. The two types of denture soft lining materials commonly used in clinical practice are methacrylate and silicone based. These together with an experimental elastomer were evaluated in this study. Fluid sorption and solubility were determined by immersion of disc specimens in food simulating fluids (distilled water, 3% acetic acid, 10% ethanol and 50% ethanol) and artificial saliva at 37±1°C with weighing at set time intervals. Similar experiments were carried out using liquids representing fatty food constituents with coconut oil and 1113307H. ardness was determined using a Shore A durometer. In order to determine wettability, contact angle was measured using a computer microscope. The surface roughness was assessed using a non-contact laser profilometer. Finally, an attempt was made to identify leachable substances from the materials investigated using a Fourier transform infrared spectrometer. An additional part of this study was to look at the adhesion of one yeast species Candida albicans to commercial materials using various protective coatings to determine their efficacy. The resultsd emonstratedth at the type of liquid simulating foods or artificial saliva, and immersion time significantly influenced the behaviour of the commercial denture soft lining materials and the experimental elastomer during in vitro testing. The two groups of materials behaviour were different. The two methacrylate-basedd enture soft lining materials showed marked absorption and solubility which may be associated with the loss of plasticisers. The two silicone-based denture soft lining materials showed much less absorption and solubility under the same conditions. The experimental elastomer showed marked swelling in oils, which was not expected, its chemical structure being similar to a methacrylate. Shore A hardness remained unchanged during the fluid immersion with the two silicone-based materials but showed measurable changes with the two methacrylate-basemd aterials and the experimentale lastomer,I ncreaseds urface roughness was also demonstrated with the two methacrylate-based materials, and decreasedc ontact angle was found with the two silicone-basedm aterials. After various surface treatment, coconut oil reduced Candida albicans adhesion in all cases.