Perturbation of cobalt 60 radiation doses by metal objects implanted during oral and maxillofacial surgery

The influence on cobalt 60 dose distributions of typical metal parts used in oral and maxillofacial surgery was studied. Relative doses were determined by exposing x-ray films in a polystyrene phantom set-up containing samples of Vitallium, titanium, and stainless steel. Optical densities were converted to doses with the aid of sensitometric curves. The results show that for normal incidence there is a 25% to 40% increase in dose at the entrance side of the metal and a 20% to 25% decrease in dose at the exit side. The enhancement effect falls off rapidly and becomes negligible at about 1 mm from the interface. The reduction effect decreases more gradually and is still evident at distances of a few centimeters. These dose perturbations should be taken into account in the planning of radiation therapy for patients in whom metal objects have been implanted.     

Construction of composite slides

This article describes a method for constructing composite slides without destroying the original slide. A conventional slide projector, rear-projector screen, modified 35 mm camera, and slide-duplicating film are required for this technique.     

Mutations in SH3BP2, the cherubism gene, were not detected in central or peripheral giant cell tumours of the jaw

Giant cell granulomas of the jaw (GCGJ) are non-familial, generally unilateral osteoclast-rich lesions that are histopathologically indistinguishable from cherubism. Cherubism is an autosomal dominant disease that is characterised by bilateral radiolucencies of the jaw, and caused by mutations that occur in SH3BP2 exon 10. The aim of the study was to screen lesional GCGJ tissue for SH3BP2 mutations. Lesional mononuclear stromal or spindle cells were microdissected from paraffin-embedded tissue from GCGJ, and DNA was then extracted and sequenced for SH3BP2 mutations associated with cherubism. No mutations were detected in 26 GCGJ (15 central, 11 peripheral), which indicated that people with GCGJ do not harbour cherubism-related germline SH3BP2 mutations, and that GCGJ do not harbour somatic SH3BP2 mutations. This suggests that cherubism and GCGJ arise on a different genetic background, and therefore detection of SH3BP2 mutations can be a useful means of distinguishing between them.     

Antimicrobial effectiveness of an herbal mouthrinse compared with an essential oil and a chlorhexidine mouthrinse

BACKGROUND: The authors investigated mouthrinses' antimicrobial effectiveness against predominant oral bacteria, as determined by the minimum inhibitory concentration (MIC). Specifically, they evaluated an herbal mouthrinse, an essential oil rinse and a 0.12 percent chlorhexidine gluconate rinse. METHODS: The authors assessed the inhibitory effects of the three test agents against 40 oral bacteria at concentrations of 1, 2, 4, 8, 16, 32, 64, 128, 256 and 512 micrograms per millliter. They inoculated plates containing basal medium and the test agents with suspensions of the test species and incubated them anaerobically at 35 degrees C. The authors interpreted the MIC as the lowest concentration of the agent that completely inhibited the growth of the test species. RESULTS: The herbal mouthrinse inhibited the growth of most of the 40 test species. Compared with the essential oil mouthrinse, the herbal mouthrinse exhibited significantly lower MICs for Actinomyces species, periodontal pathogens Eubacterium nodatum, Tannerella forsythia and Prevotella species, as well as the cariogenic pathogen Streptococcus mutans. The chlorhexidine gluconate rinse had the lowest MICs compared with the essential oil rinse and the herbal rinse for all test species examined. CONCLUSIONS: Although less potent than the chlorhexidine gluconate rinse, the herbal rinse was more effective than the essential oil rinse in inhibiting the growth of oral bacteria in vitro. CLINICAL IMPLICATIONS: The data suggest that the herbal mouthrinse may provide oral health benefits by inhibiting the growth of periodontal and cariogenic pathogens. In vivo clinical testing is essential to confirm in vitro results.     

Relationship between kinematic center and TMJ anatomy and function

The kinematic center (KC)-defined by coinciding jaw-opening/-closing and protrusion-retrusion trajectories-has been proposed in the literature as a reference point to represent TMJ movements. In this study, we tested whether the KC lies in a peculiar anatomical point and whether its trajectory reflects intra-articular distance. In 11 asymptomatic individuals (seven females, four males, aged 24-37 yrs), 4 openings/closings and 4 protrusions/retrusions were tracked with dynamic stereometry. In a 3D lattice (0.5 mm grid) constructed solidly around each condyle, the KC was the point with maximal cross-correlation between opening-closing and protrusion-retrusion paths. KC trajectories were more cranial on closing than on opening, consistent with intra-articular distances being smaller on closing than on opening. However, KCs were never located on condylar main axes (distance, 4.5 +/- 2.9 mm), nor did they coincide with points best approximating fossa shapes (distance, 12.5 +/- 6.4 mm). The kinematic center's anatomical and functional significance therefore appears to be questionable.     

An audit of paediatric dental treatments carried out under general anaesthesia in a sample of Spanish patients

OBJECTIVE: To evaluate the success and failure rates of the clinical procedures carried out under general anaesthesia in disabled or medically comprised and healthy children. BASIC RESEARCH DESIGN: Retrospective study included 47 patients who received dental treatment under general anaesthesia, grouped according to whether they were disabled or medically compromised (group A, n = 16) or not (group B, n = 31), and subgrouped according to whether they were under or over 6 years of age. RESULTS: Mean duration of anaesthesia was 2 hours and 25 minutes, with a range of 1 to 4 hours. The percentage of children followed up was 87%. The procedures performed were: 105 preformed metal crowns, 142 restorations, 85 pulpotomies and 166 extractions. The success rate was 93% for preformed metal crowns, 96% for pulpotomies and 90% for restorations. CONCLUSIONS: General anaesthesia is necessary in some children, but should be complemented with a preventive programme, behavioural remodelling and a follow-up schedule to avoid having to repeat the use of general anaesthesia.     

In vitro study of the inactivation by dentine of some endodontic medicaments and their bases

Background: The aim of this study was to investigate the antimicrobial effect of endodontic medicaments and their bases in the presence of dentine powder. Methods: The medicaments tested were Ledermix paste, Pulpdent paste, a 50:50 combination of the Pulpdent:Ledermix and their bases. The test organism was Enterococcus faecalis ATCC 29212. The presence or absence of dentine was examined as well as the effect of autoclaving dentine. Serial dilutions of samples at 1 hour, 1 day and 3 days were used for colony counting. The effects of dentine powder on pH for saturated Ca(OH)₂ solution and Pulpdent paste at 1 hour and 24 hours were also measured. Results: Pulpdent and the 50:50 combination of Pulpdent:Ledermix completely inhibited the growth of E. faecalis from 1 hour onwards, and these results were not affected by the presence/absence of dentine powder, pre‐incubation period, timing of autoclaving, or exposure time. Saturated solutions of Ca(OH)₂ are prone to inactivation by dentine powder unlike Pulpdent paste. Ledermix paste took 3 days to exert a significant effect on the growth of E. faecalis. Conclusions: In this laboratory study, both Pulpdent and the 50:50 mixture of Pulpdent with Ledermix were effective medicaments against E. faecalis in the presence of dentine powder.     

Comparison of the instructional efficacy of an internet-based temporomandibular joint (TMJ) tutorial with a traditional seminar

There has been growing interest in the use of virtual learning environments (VLEs) by universities over the past decade to supplement traditional teaching methods. In this study a tutorial providing information about the temporomandibular joint (TMJ), temporomandibular disorders and teaching of a thorough TMJ examination was developed on a VLE platform to enable students to enhance their examination and diagnostic skills. The success of this VLE tutorial was compared with conventional teaching by a cross-over trial. Thirty students were initially randomly allocated to one of two groups; Group 1 completed the VLE tutorial and Group 2 attended the face-to-face seminar in the first instance. The groups then crossed over and had the other method of teaching provided. The findings from the cross-over trial and the students' feedback indicated that no differences were found between either teaching modes, and both are equally effective at delivering information to students. In addition, the order in which the students received the teaching did not make a difference, but giving the teaching twice reinforced their knowledge. There is a strong case to be made for introducing clinical lectures on a VLE platform, and this form of e-learning is, in general, well perceived by new generations of students.     

Concepts for the treatment of adolescent patients with missing permanent teeth

INTRODUCTION: Missing permanent teeth is observed with syndromes or is frequently hereditarily propagated in families. The treatment of these patients is a multi-task of specialists of oral surgery, orthodontics and prosthodontics. DISCUSSION: Despite functional and aesthetic considerations, the main problem of all treatment is that it had to be performed in a growing child. This article discusses the conventional and implant-driven concepts to treat patients from childhood to adolescence with selective or multiple missing permanent teeth.