The influence of maxillary central incisor height-to-width ratio on perceived smile aesthetics.

OBJECTIVE: To determine the influence of varying the width-to-height ratio of maxillary central incisors on perceived smile aesthetics. DESIGN: Cross-sectional study. SETTING: Postgraduate dental teaching hospital. METHODS: A posed female smile was digitally modified using Adobe Photoshop(®). Three images were created; central incisors with normal form, tooth wear and delayed apical migration. For each image the length of the teeth was altered to create a set of nine images with normal form (66% to 96% width-to-height ratios), and sets of five images with tooth wear and with delayed apical migration (78% to 96% ratios). The images in each set were ranked in order of most to least attractive by 32 dentists, 32 technicians and 32 patients. RESULTS: An 82% width-to-height ratio was perceived as the most attractive for normal central incisors although there is variability in the responses. There is a definite trend towards the extremes of very long or very short teeth being less attractive. The very long central incisors, and those with tooth wear were perceived as unattractive. The patients rated fewer images from the tooth wear and delayed apical migration sets as unattractive compared to the dentists and technicians. CONCLUSION: The width-to-height ratios perceived as most attractive correspond with the higher end of ideal ratios proposed in the dental literature (75-80% width-to-height ratio). Significant differences exist between the aesthetic perceptions of dentists, technicians and patients and there is lack of agreement within each group, in particular within the patient group. The individual variability in patient response should be taken into account during treatment planning.

Survival analysis of composite Dahl restorations provided to manage localised anterior tooth wear (ten year follow-up).

OBJECTIVE: To evaluate ten-year survival and clinical performance of resin-based composite restorations placed at increased vertical dimension as a 'Dahl' type appliance to manage localised anterior tooth wear.Design A prospective survival analysis of restorations provided at a single centre.Setting UK NHS hospital and postgraduate institute. METHODS: The clinical performance of 283 composite resin restorations on 26 patients with localised anterior tooth wear was reviewed after a ten year follow-up period. The study used modified United States Public Health Service (USPHS) criteria for assessing the restorations. Survival of the restorations was analysed using Kaplan-Meier survival curves, the log-rank test, and the Cox proportional hazards regression analysis. RESULTS: The results indicated that the median survival time for composite resin restorations was 5.8 years and 4.75 years for replacement restorations when all types of failure were considered. The restorations commonly failed as a result of wear, fracture and marginal discoloration. The factors that significantly influenced the survival of these restorations were the incisal relationship, aetiology, material used, and the nature of opposing dentition. The biological complications associated with this treatment regime were rare. Patient satisfaction remained high despite the long term deterioration of the restorations. CONCLUSION: With some degree of maintenance, repeated use of composite resin restorations to treat localised anterior tooth wear at an increased occlusal vertical dimension is a viable treatment option over a ten-year period.

The influence of varying maxillary incisal edge embrasure space and interproximal contact area dimensions on perceived smile aesthetics.

OBJECTIVE: The aim of this study was to determine the influence of incisal edge embrasure space and interproximal contact area dimensions on perceived smile aesthetics. DESIGN: Cross-sectional study. SETTING: Postgraduate dental teaching hospital. METHODS: A photograph of a smiling female, displaying only the lips and maxillary teeth was digitally altered. First, the proportions of the incisal edge embrasure spaces were modified to produce five different images. Secondly, the lengths of the interproximal contact areas were altered to produce five different images. The two sets of photographs were ranked from 'most attractive' to 'least attractive' by 35 dentists, 35 dental technicians and 35 patients. RESULTS: An embrasure space arrangement where the size of the embrasures increases progressively distally from the midline was deemed most attractive; absence of embrasure spaces was deemed least attractive. In assessing the interproximal contact areas, all groups assessed an arrangement where the areas between the teeth were equal (and 50% the length of the central incisor) as most attractive, and where the contact areas increased in length progressively distally from the midline as least attractive. There were few statistically significant differences between the groups in these perceptions. CONCLUSION: Whilst there is broad agreement in what the participant groups deem to be aesthetic, our findings do not wholly correspond to the 'ideals' that have been previously suggested in the dental literature.

Investigation of the effect of a proprietary dental waterline disinfectant on shear bond strengths of Panavia 21 to enamel and dentine.

This study investigated the effect of 'Alpron mint', a dental unit waterline disinfectant, on shear bond strengths between 'Panavia 21' resin based cement and tooth tissue. Eighty-eight human premolar tooth specimens were prepared in either enamel (N=44) or dentine (N=44). Half the specimens within each group were irrigated with an Alpron mint solution and the other half with distilled water (control) prior to application of Panavia 21 resin luting cement. There was no significant difference in shear bond strengths for both enamel and dentine with Alpron mint irrigation compared with distilled water (P = 0.245).

Smile aesthetics.

The aim of this article is to outline some of the factors practitioners should take into consideration when planning optimal smile aesthetics. The components of the smile that will be discussed include the smile are, incisor/gingival display, smile width, gingival aesthetics, tooth proportionality/symmetry, contacts/connectors/embrasures and the dental midlines.

A clinical evaluation of the individual repeatability of three commercially available colour measuring devices.

OBJECTIVE: The objective of this study was to undertake a clinical evaluation of the individual repeatability of three colour measuring devices. DESIGN: Clinical study. Setting Eastman Dental Hospital. METHODS: Under standardised clinical conditions, one trained operator using three colour measuring devices (Vita Easyshade, X-Rite ShadeVision and Spectroshade Micro) recorded three shade measurements (cervical, body and incisal) for each of the upper maxillary anterior teeth in 20 participants. This sequence of measurements was repeated for each of the shade machines. The output recorded from each sequence included Vita classic shades and CIE Lab co-ordinates. Ethical approval was obtained from the joint University College London and University College London Hospitals. RESULTS: Spectroshade Micro had good agreement Cohen Kappa score (0.80) for repeatability of Vita shades and also had 82.7% proportion of complete agreement for Vita shades. The proportion of complete agreement for Vita shades for the Easyshade and X-Rite ShadeVision machine were 50% and 59% respectively. For CIE Lab co-ordinates the Spectroshade Micro provided the narrowest range of 'Bland and Altman' agreement limits for all the co-ordinates recorded. CONCLUSION: The Spectroshade Micro machine provided the most repeatable measurements. Narrower limits of agreement indicate greater consistency compared to Easyshade and X-Rite ShadeVision.

The influence of varying maxillary lateral incisor dimensions on perceived smile aesthetics.

OBJECTIVE: The aim of this study was to determine the influence of varying the dimensions of the maxillary lateral incisors on perceived smile aesthetics. DESIGN: Clinical study. SETTING: Postgraduate dental teaching hospital. METHODS: A photograph of a female smile displaying only the lips and teeth was digitally altered. First, the width of the maxillary lateral incisors, in proportion to the central incisor, was altered at 5% intervals to produce six images (52%, 57%, 62% [the 'golden proportion'], 67%, 72% and 77%). In a second group, the length of the lateral incisor was altered at 0.5 mm increments to produce five images with the lateral incisor 0.5 mm, 1 mm, 1.5 mm, 2 mm and 2.5 mm shorter than the adjacent central incisor. The photos were ranked from 'most attractive' to 'least attractive' by 41 hypodontia patients, 46 non-hypodontia 'control' patients and 30 dentists. RESULTS: The 67% followed by the 72% lateral-to-central width proportions were the 'most preferred' by all groups. A maxillary lateral incisor that is 1-1.5 mm shorter than the central incisor was the 'most popular' maxillary lateral incisor length. The very short and very long maxillary lateral incisor was consistently perceived as 'least attractive'. CONCLUSION: There is no evidence to suggest that the golden proportion should be considered the ideal aesthetic standard when creating space for the replacement of missing lateral incisors.

Adult and paediatric basic life support: an update for the dental team.

The aim of this paper is to review the current Resuscitation Council (UK) basic life support guidelines. The main changes made to the guidelines published in 2000 are that for adult basic life support no initial rescue breaths should be delivered before commencing chest compressions and that the compression to ventilation ratio should be 30:2 irrespective of the number of rescuers. For children over the age of one year, two rescuers should provide life support with a compression to ventilation ratio of 15:2. There is still a need to deliver rescue breaths before starting compressions in the child patient.

Effect of immersion disinfection with Perform-ID on alginate, an alginate alternative, an addition-cured silicone and resultant type III gypsum casts.

OBJECTIVE: This study investigated the effect of a commonly used immersion disinfectant upon three different impression materials and any subsequent effects on the abrasion resistance, hardness and surface detail reproduction of gypsum casts. DESIGN: A laboratory study. MATERIALS AND METHODS: Under standardised conditions a total of 120 impressions were made of a ruled test block using irreversible hydrocolloid (Alginoplast), an 'alginate alternative' addition-cure silicone (Position Penta) and a conventional addition-cure silicone (President). The impressions were examined for surface detail reproduction prior to and after disinfection with Perform-ID. The type III casts were evaluated for surface detail reproduction, surface hardness and abrasion resistance. RESULTS: (1) None of the disinfected alginate specimens could reproduce the 50 microm line. (2) Casts produced from the disinfected alginate were significantly less hard than from disinfected Position Penta and President (P <0.001). (3) Disinfection significantly affected the abrasion resistance of casts made from Position Penta (P = 0.029). (4) Disinfection did not significantly affect President or its subsequent casts (P >0.05). CONCLUSION: If disinfecting with Perform-ID, the impression should be made with a conventional addition-cured silicone if good surface detail reproduction of the impression material and a hard and abrasion resistant type III gypsum cast are required.

Hydrogen peroxide tooth-whitening (bleaching) products: review of adverse effects and safety issues.

Hydrogen peroxide in the form of carbamide peroxide is widely used for tooth whitening (bleaching), both in professionally- and in self-administered products. Adverse effects have become evident. Cervical root resorption is a possible consequence of internal bleaching and is more frequently observed in teeth treated with the thermo-catalytic procedure. Tooth sensitivity is experienced in 15-78% of patients undergoing external tooth bleaching. However, clinical studies addressing other adverse effects are lacking. Direct contact with hydrogen peroxide induces genotoxic effects in bacteria and cultured epithelial cells, but the effect is reduced or totally abolished in the presence of metabolising enzymes. Several carcinogenesis studies, including the hamster cheek pouch model, indicate that hydrogen peroxide (H(2)O(2)) might possibly act as a promoter. Until further clinical research is concluded to address the question of possible carcinogenicity, it is recommended that: tooth-bleaching products using concentrated H(2)O(2) should not be used without gingival protection; that H(2)O(2) containing products should be avoided in patients with damaged or diseased soft tissues. For nightguard vital bleaching, minimal amounts of low dose H(2)O(2) (including in the form of carbamide peroxide) are preferred, thereby avoiding prolonged and concentrated exposures.

British Dental Journal based Continuing Professional Development: a survey of participating dentists and their views.

OBJECTIVE: There is little information available on journal based verifiable continuing professional development (CPD). The aim of this study was to survey those dentists who have undertaken this form of CPD and elicit their views. DESIGN: A questionnaire survey. METHOD: Four hundred dentists who had registered to undertake CPD with the British Dental Journal (BDJ) were randomly selected and sent a questionnaire. RESULTS: Three hundred and twelve questionnaires were returned (78%) of these 181 (58%) were male and 131 (42%) were female. Of the 312, 307 had undertaken the BDJ CPD initiative. Two hundred and sixty eight respondents (87.3%) agreed/strongly agreed that the BDJ CPD satisfied their personal CPD needs. Two hundred and eighty three (92.2%) agreed/strongly agreed that their knowledge has been increased as a result of undertaking the BDJ CPD initiative. Two hundred and twenty agreed/strongly agreed (71.7%) that an element of their clinical practice had changed as a result of undertaking the BDJ CPD initiative. CONCLUSION: Journal based learning appears to be an effective way of undertaking verifiable CPD.

Drug-induced disorders of teeth.

It is essential that every health care professional who is involved with the prescription or recommendation of drugs be fully aware of any resultant disorders that may arise as a side-effect. A range of drugs can affect the teeth. In this review article, drugs that have the potential to induce changes in teeth have been classified as those leading to tooth discoloration (intrinsic and extrinsic), physical damage to tooth structure (enamel, dentin, and cementum), and alteration in tooth sensitivity.

Treatment planning for the loss of first permanent molars.

During the mixed-dentition stage of dental development, dentists may encounter patients with first permanent molars considered to have a poor long-term prognosis. In this situation, extraction of the tooth and space closure or use of the extraction space for future orthodontic treatment should be considered. The aim of this article is to give guidelines about treatment planning for patients who have first molars with a poor prognosis during the mixed-dentition stage.

The transmissible spongiform encephalopathies (prion diseases): a review for dental surgeons.

The transmissible spongiform encephalopathies (prion diseases) are a fatal group of neurological diseases characterised by the accumulation of an abnormal form of prion protein in the brain. In humans, these disorders occur in sporadic, acquired and familial forms. Outbreaks of bovine spongiform encephalopathy, predominantly in the United Kingdom, and the emergence of a clinically and pathologically distinct human prion disease, variant CJD, has generated much interest in the transmissible spongiform encephalopathies. As the agent is detectable in lymphoid and neural tissue in variant CJD, clinicians should be aware of the possibility of cross infection of the causative agent. This is particularly important because the abnormal prion protein is resistant to routine sterilisation procedures. This article reviews the transmissible spongiform encephalopathies, and summarises guidelines concerning prevention of crossinfection when treating patients with or at risk of developing prion disease.