Tobacco and alcohol related to the anatomical site of oral squamous cell carcinoma

The aim of the present study was to evaluate the possible relationship between tobacco smoking and alcohol drinking and the anatomical sites of squamous cell carcinoma (SCC) of the lip and oral cavity. For this purpose, a case-case study has been performed in 690 patients. The study was focused on the relative risk (RR) or developing SCC at various (sub)sites, for smokers and drinkers of alcohol (divided into moderate and heavy users) relative to non-smokers and non-drinkers. Estimates of ratios of these relative risks were obtained. The relative risk associated with tobacco smoking, adjusted for the use of alcohol, appeared to be highest for SCC in the retromolar area, followed by the floor of mouth, whereas the lowest RR was found in the cheek mucosa. For alcohol drinking, adjusted for tobacco smoking, RR of SCC of the floor of mouth was significantly higher than for the tongue, whereas the RR of SCC of the cheek appeared to be lowest. Furthermore, this study suggests that the contrasts between relative risks, observed by anatomical site of oral SCC, are more pronounced for tobacco smoking than for the use of alcohol. The possible local and systemic factors responsible for these variations of susceptibility for tobacco and alcohol within the oral cavity are discussed.     

Immediate functional loading of single-tooth TiO2 grit-blasted implant restoration. A controlled prospective study in a porcine model. Part II: Histology and histomorphometry

Background: Evidently, there is a fast‐moving shift from delayed to immediate implant loading. The hypothesis to be tested was that bone reactions adjacent to single TiO₂‐microthreaded implants exposed to immediate masticatory loading for 10 weeks after placement would modulate osseointegration. Materials and Methods: Cylindrical‐ and tapered‐designed implants (Astra Tech AB, Mölndal, Sweden) replaced first and third mandibular premolars respectively in 12 pigs. The animals were allocated into two groups based on soft and hard diet feeding. Each animal received, at random positions, four different masticatory loading conditions: implant with either (1) a cover screw only, (2) a healing abutment, (3) an implant with a crown without occlusal contact, or (4) an implant with a crown in contact with the antagonistic teeth. Results: Histomorphometry showed that there were no statistically significant differences in bone‐implant contact (BIC), bone mass inside/outside of the threads and soft tissue ingrowth ratio for all the implants at 10 weeks after placement irrespective of masticatory loading condition. Bone loss showed a trend of progressive increase for implants with a healing abutment toward implants with occlusal contact. Conclusions: The results of this study rejected the hypothesis and could be explained by the fact that grit‐blasted acid‐etched implants were already placed in dense bone.     

Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials

OBJECTIVES: To determine whether parachutes are effective in preventing major trauma related to gravitational challenge. Design Systematic review of randomised controlled trials. DATA SOURCES: Medline, Web of Science, Embase, and the Cochrane Library databases; appropriate internet sites and citation lists. STUDY SELECTION: Studies showing the effects of using a parachute during free fall. MAIN OUTCOME MEASURE: Death or major trauma, defined as an injury severity score > 15. RESULTS: We were unable to identify any randomised controlled trials of parachute intervention. CONCLUSIONS: As with many interventions intended to prevent ill health, the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials. Advocates of evidence based medicine have criticised the adoption of interventions evaluated by using only observational data. We think that everyone might benefit if the most radical protagonists of evidence based medicine organised and participated in a double blind, randomised, placebo controlled, crossover trial of the parachute.     

Training pathways for careers in dental, oral, and craniofacial research

There are virtually unlimited opportunities for biomedical research training through either extramural or intramural training mechanisms, with programs designed for both the pre- and postdoctoral educational levels. The only difficulty is selecting from the vast array of research topic areas.     

Factors influencing defects of rotary nickel-titanium endodontic instruments after clinical use

This study examined used, discarded rotary nickel-titanium instruments obtained from 14 endodontists in four countries, and identified factors that may influence defects produced during clinical use. A total of 7,159 instruments were examined for the presence of defects. Unwinding occurred in 12% of instruments and fractures in 5% (1.5% torsional, 3.5% flexural). The defect rates varied significantly among endodontists. Instrument design factors also influenced defect rate, but to a lesser extent. The mean number of uses of instruments with and without defects was 3.3 +/- 1.8 (range: 1-10), and 4.5 +/- 2.0 (range: 1-16), respectively. The most important influence on defect rates was the operator, which may be related to clinical skill or a conscious decision to use instruments a specified number of times or until defects were evident.     

Is occlusion becoming more confusing? A plea for simplicity

It is not difficult to observe and record patient occlusal characteristics before starting simple or complex occlusal rehabilitations. If this is done, and if the subsequently placed crowns and fixed prostheses are constructed in observation of similar characteristics, clinical success usually is the result. Deviations from the suggestion to duplicate the "normal" occlusion should be made when the original natural occlusion had caused overt pathosis, or when all teeth or one arch of the teeth is being restored at one time. If this is the case, centric relation occlusion is more reproducible and easier to develop than occlusion with a shift from centric relation to centric occlusion. Peculiar requests of patients relative to occlusal positioning, or routine dependence on various devices to predetermine occlusal characteristics for rehabilitation (as is currently popular in some groups), should be considered, but they should be tempered with careful observation of preoperative occlusal characteristics.     

A virtual reality dental simulator predicts performance in an operative dentistry manikin course

This study was designed to test the ability of a virtual reality dental simulator to predict the performance of students in a traditional operative dentistry manikin course. Twenty-six dental students were pre-tested on the simulator, prior to the course. They were briefly instructed and asked to prepare 12 class I cavities which were automatically graded by the simulator. The instructors in the manikin course that followed were unaware of the students' performances in the simulator pre-test. The scores achieved by each student in the last six simulator cavities were compared to their final comprehensive grades in the manikin course. Class standing of the students in the simulator pre-test positively correlated with their achievements in the manikin course with a correlation coefficient of 0.49 (P = 0.012). Eighty-nine percent of the students in the lower third of the class in the pre-test remained in the low performing half of the class in the manikin course. These results indicate that testing students in a dental simulator, prior to a manikin course, may be an efficient way to allow early identification of those who are likely to perform poorly. This in turn could enable early allocation of personal tutors to these students in order to improve their chances of success.