A novel approach to study in situ enamel erosion and abrasion lesions.

OBJECTIVES: This study investigated previous hypotheses that the tongue can abrade acid softened/eroded enamel surfaces. METHODS: Twelve upper removable appliances each retaining 2 anterior and 2 posterior human enamel specimens were constructed. Each specimen was exposed to acid on both surfaces, but only one surface was allowed contact with the tongue. Therefore, 96 surfaces were assessed. Appliances were worn from 9.30 to 17.00 Monday to Friday for 22days. Acid eroded lesions were created by immersing the specimens for 5min in 50ml orange juice three times daily. Enamel loss was measured using Quantitative light- induced fluorescence (QLF) and Non- contact profilometry (NCLP) and the differences (D) between tongue (Dt) and palate facing (DP) surfaces determined. RESULTS: %ΔFD(t-p) from the two anterior specimens were greater than from those placed posteriorly with mean values of 15.9% (±9.1) and 14.4% (±8.4), 5.6% (±8.7) and 4.5% (±6.6) respectively. Similarly, NCLP data showed anterior specimens had greater differences for mean step height (MSH) between tongue- facing and the palate- facing (control) surfaces than posterior specimens. MSHD(t-p) values were 59.4µm (±30.3) for anterior tongue facing surfaces and 55.5µm (±29.4) for posterior palate facing surfaces. For the posterior specimens MSH was 48.1µm (±26.1) and 51.7µm (±30.4) respectively (p<0.05). CONCLUSION: The greater enamel surface loss of the anterior specimens demonstrates that abrasion by the tongue on acid softened/eroded enamel in situ is likely.

Ochronosis in a murine model of alkaptonuria is synonymous to that in the human condition.

OBJECTIVE: Alkaptonuria (AKU) is a rare genetic disease which results in severe early onset osteoarthropathy. It has recently been shown that the subchondral interface is of key significance in disease pathogenesis. Human surgical tissues are often beyond this initial stage and there is no published murine model of pathogenesis, to study the natural history of the disease. The murine genotype exists but it has been reported not to demonstrate ochronotic osteoarthropathy consistent with the human disease. Recent anecdotal evidence of macroscopic renal ochronosis in a mouse model of tyrosinaemia led us to perform histological analysis of tissues of these mice that are known to be affected in human AKU. DESIGN: The homogentisate 1,2-dioxygenase Hgd(+/)(-)Fah(-)(/)(-) mouse can model either hereditary tyrosinaemia type I (HT1) or AKU depending on selection conditions. Mice having undergone Hgd reversion were sacrificed at various time points, and their tissues taken for histological analysis. Sections were stained with haematoxylin eosin (H&E) and Schmorl's reagent. RESULTS: Early time point observations at 8 months showed no sign of macroscopic ochronosis of tissues. Macroscopic examination at 13 months revealed ochronosis of the kidneys. Microscopic analysis of the kidneys revealed large pigmented nodules displaying distinct ochre colouration. Close microscopic examination of the distal femur and proximal fibula at the subchondral junctions revealed the presence of numerous pigmented chondrocytes. CONCLUSIONS: Here we present the first data showing ochronosis of tissues in a murine model of AKU. These preliminary histological observations provide a stimulus for further studies into the natural history of the disease to provide a greater understanding of this class of arthropathy.

Colour match between porcelain and porcelain-repairing resin composites.

The aim of this study was to evaluate the differences in colour between dental porcelain and porcelain-repairing resin composites. Porcelain discs were fabricated using four dentine shades in 1mm and 2mm thicknesses. Another series of discs was fabricated in 1mm and 2 mm thicknesses using three different brands of composite. Four single shades were used for the 1mm thick discs, and four single and 12 combined shades for the 2mm thick discs. The colour was measured using a spectrophotometer and colour differences deltaE* were calculated between samples. Colour differences were in the range of (deltaE* = 3.5-26.9), above the accepted threshold for perceptibility (deltaE* > 1) with a number above the threshold for what is considered to be clinically acceptable (deltaE* > 5.5). Improvements in colour match were seen for certain shade combinations of repairing composites, in contrast to when a single shade of composite was used.

Dental management of the elderly patient.

UNLABELLED: The dental management of the elderly individual is becoming more of an issue in both general dental practice and specialist prosthodontic practice. This is because, in general, the population is living longer and often elderly patients are retaining their natural teeth into their old age. In addition, there are often related significant medical, social and oro-dental issues that require consideration. CLINICAL RELEVANCE: The dental management of the elderly patient is an increasing problem. This paper seeks to consider the main relevant issues pertaining to this important subject area.

Working length determination in general dental practice: a randomised controlled trial.

OBJECTIVE: To evaluate the ability of apex locators as a tool in determining working length in comparison to traditional working length radiographs in general dental practice. DESIGN: Randomised controlled clinical trial. SETTING: General dental practices in the North West of England.Subjects Adults requiring root canal treatment of at least one tooth with minimal or moderate difficulty. INTERVENTION: Root canal treatment was carried out with the working length determined by apex locator in the treatment group (AL), and periapical radiograph in the control group (PA). OUTCOME MEASURE: The acceptability of the master cone gutta percha measured from a radiograph before obturation was used as the primary outcome. RESULTS: Twenty-one of 23 fillings in the AL group were judged as acceptable, compared to 17 of 23 fillings in the PA group. This difference was not statistically significant. CONCLUSION: In general dental practice, no significant difference was found in working length determined using apex locator combined with a master cone GP radiograph or using the conventional method. There is a need for larger trials to investigate these methods further.

Comparison of the effects of whole and juiced fruits and vegetables on enamel demineralisation in situ.

We compared the effect on enamel demineralisation in situ of both whole and juiced fruits and vegetables. Volunteers wore removable mandibular appliances carrying pre-demineralised human enamel slabs and consumed one of the test foods 7 times a day for 10 days. The test foods were apples, oranges, grapes, carrots, and tomatoes, consumed either whole (sugars located intrinsically) or as a juice (extrinsic or free sugars). Raisins containing 64% sugars, but intrinsic by definition, were also studied. The mineral profile of the enamel slabs was studied before and after the test period using transverse microradiography and showed further demineralisation for all test foods, irrespective of the form of consumption. Significant demineralisation was also observed with raisins. No significant differences were found between the solid and juiced foods. In conclusion, sugars present intrinsically on consumption had a similar demineralising potential as free sugars and could not be considered less cariogenic.

Performance assessment of Vita Easy Shade spectrophotometer on colour measurement of aesthetic dental materials.

Four different shades were used to produce 20 samples of resin-based composite and 20 samples of porcelain to evaluate the performance ability of an intra oral test spectrophotometer compared to a reference spectrophotometer. The absolute colour coordinates CIELAB values measured with both spectrophotometers were significantly different (p < 0.001). However, a high correlation was found (p < 0.001) despite the low concordance noticed. The colour difference deltaE* values calculated between different shades also were significantly different between both spectrophotometers (p < 0.05). Therefore, the Easy Shade can be used in dental practice and dental research with some limitations.

An investigation into the effect of try-in pastes, uncured and cured resin cements on the overall color of ceramic veneer restorations: an in vitro study.

OBJECTIVES: The aim of this study was to assess how different shades of try-in pastes, uncured and cured resin cements influence the overall color of porcelain veneer restorations. METHODS: Porcelain veneers of shade Vita 1M1 VM7 and 1mm thick were applied to bovine teeth using three shades of resin cement and their try-in paste produced by three manufacturers. Analysis of variance was carried out on the color difference values (ΔE*) between the Aquagel and both the try-in paste and cured resins. An assessment of the clinical significance of ΔE* between the try-in paste and the cured resin and also between the uncured and cured resin was made. RESULTS: There were statistically significant differences in veneers' colors when using different shades of both Calibra and Nexus resin cements (p<0.05). Also, statistically significant differences were noticed when using different shades of both Rely-X and Nexus try-in pastes (p<0.05). Color differences produced between the try-in pastes and the corresponding shades of cured resin cements ranged from ΔE* 1.05 to 3.34. The color differences between uncured and cured resins of the same shade ranged from ΔE* 0.78 to 1.41. CONCLUSIONS: Different colored try-in pastes and resin cements produced color changes which are clinically useful in changing the color of veneer restorations and therefore aid color matching to adjacent dentition. Clinically significant differences were found between try-in pastes and the cured resin of the same shade, however, there were relatively small changes measured between uncured and cured resins. The color match achieved by the try-in paste has to be treated with caution and further assessment of the restoration made with the resin in place before curing is recommended.

The erosive potential of some alcopops using bovine enamel: an in vitro study.

OBJECTIVES: Alcoholic soft drinks have become increasingly popular and have high concentrations of citric acid and alcohol so might have the potential to cause dental erosion. This study aimed to investigate the erosive potential of alcopops on bovine enamel in vitro. METHODS: Six bovine upper incisors were prepared and sectioned to give six slabs per tooth, 4mm x 4mm each. Each slab was covered with nail varnish, leaving an exposed window (2mm x 2mm). Samples were immersed in 20ml of each of the test solutions for 20min, 1h, and 24h under gentle agitation (100rpm). Enamel surface loss was determined using Quantitative Laser Fluorescence (QLF), Non-contact Profilometry (NCP) and Transverse Microradiography (TMR). RESULTS: Enamel loss occurred with all test drinks and the positive control (p<0.05), and the depth of lesion correlated with pH and time. No significant difference was observed between 20min and 1h exposure, although both times had significantly (p<0.05) greater erosion when compared with baseline. Within each alcopops group significant erosion had occurred at 24h exposure compared with the baseline and previous times. CONCLUSION: All the tested alcopops resulted in significant enamel loss at 24h (p<0.001) with direct correlation between degree of enamel loss and both pH and increasing exposure time.

Analysis of dermatologic events in patients with cancer treated with lapatinib.

PURPOSE: Dermatologic events (DEs) in patients with cancer treated with lapatinib, a small-molecule dual tyrosine kinase inhibitor (TKI) of epidermal growth factor receptor (EGFR [ErbB1]) and HER2 (ErbB2), were characterized. PATIENTS AND METHODS: Nine clinical trials of metastatic cancer were included in this analysis. Lapatinib was administered at doses ranging from 1000 to 1500 mg/day as monotherapy (n=928) or in combination with paclitaxel or capecitabine (n=491). Patients not treated with lapatinib comprised the control group. Dermatologic events included hand-foot syndrome, rash, hair disorder, dry skin, pruritus/urticaria, skin disorder, skin infection, and nail disorder; DEs were characterized based on type, time to onset, severity, duration, and required interventions. RESULTS: Fifty-eight percent of patients treated with lapatinib monotherapy, 74% treated with lapatinib plus paclitaxel or capecitabine, and 53% in the control group developed DEs. Among patients receiving lapatinib monotherapy, 55% experienced grade 1/2 DEs, 3% had grade 3 DEs, and no grade 4 DEs were observed. The most common DE was rash (43%); all other events occurred in

An update on resin-bonded bridges.

Since the introduction of the 'Rochette' bridge in the 1970s the resin-bonded bridge has undergone a number of developments to become a commonly used technique for replacement of a missing tooth, especially in a minimally restored dentition. One of the major advantages of the resin-bonded bridge is that it requires less tooth preparation than conventional bridgework, with some authorities advising no preparation at all. Some reports have suggested poor long-term success rates, however, if used in appropriate clinical situations, this treatment modality can be extremely successful. The aim of this paper is to review the literature relating to resin-bonded bridges and suggest recommendations for clinicalpractice concerning the provision of resin-bonded bridges.

Undergraduate requirements in restorative dentistry in the UK and Ireland.

OBJECTIVES: To ascertain the requirements in restorative dentistry that undergraduate dental students have to fulfil in order to sit the finals examinations in dental schools in the UK and Ireland and to compare those requirements with the competencies stipulated by the GDC in The first five years. METHODS: Fifteen anonymised questionnaires, of open and closed question design, were sent by post to academics in the university departments of restorative dentistry in each of the undergraduate dental schools in the UK and Ireland. The first section concerned numerical information regarding total numbers of procedures that were required to be completed in undergraduate restorative dentistry. The second section was designed to ascertain information as to how decisions are made with respect to an undergraduate's readiness to sit the finals examination in restorative dentistry (such as continual assessment and/or competency assessments). RESULTS: A total of 15 replies were received for analysis, a 100% response rate. Several institutions emphasised that they do not have 'requirements', but provide guidelines as to what should be achieved. Six institutions did not have set numerical requirements for direct placement restorations or bridges. The number of direct placement restorations required at the other nine institutions ranged from 50 to 160. Five institutions did not have numerical requirements for dentures; four institutions did not set numerical targets for crowns, veneers, inlays/onlays or endodontics. In institutions where numerical requirements were not used, forms of competency assessments were completed. The requirements across all institutions for periodontology, integrated treatment planning and completed cases were ill-defined. CONCLUSIONS: This study shows that there is a wide disparity amongst institutions in the UK and Ireland with regards to finals requirements in restorative dentistry. Ideally, such requirements should be similar between institutions and should be closely mapped to the GDC's required learning outcomes (The first five years) for the UK institutions.

The ageing UK population--considerations for the restorative dentist.

The scope of gerodontology and more specifically that of restorative dentistry (which in the UK includes the disciplines of endodontics, periodontics, prosthodontics and operative dentistry) within gerodontology, is expanding. This is true for several reasons. Firstly, the population, in both the UK and most of the western world is generally living longer. Secondly, more elderly patients are retaining their natural teeth longer into old age--thereby necessitating ongoing restorative dentistry input for their maintenance. In addition, many patients' expectations are increasing with regards to restorative dentistry. Natural teeth that were erstwhile considered as automatic candidates for extraction may now be regarded differently, especially if they are considered a 'strategic' tooth within the arch. The aim of this paper is to give a perspective as to how some of the more common restorative dentistry issues that beset the elderly population are addressed in the UK. This paper will focus on operative dentistry and prosthodontic aspects of restorative dentistry for elderly patients.

The knowledge of healthcare professionals regarding elderly persons' oral care.

OBJECTIVE: The aim of this study was to compare the knowledge and views of nursing staff on both acute elderly care and rehabilitation wards regarding elderly persons' oral care with that of carers in nursing homes. SUBJECTS: One hundred nurses working on acute, sub-acute and rehabilitation wards for elderly people (Group 1) and 75 carers in nursing homes (Group 2) were surveyed. DESIGN: A semi-structured questionnaire. RESULTS: Similar percentages of each group of nurses were registered with a dentist (86% and 88% respectively), although more hospital-based nurses were anxious about dental treatment compared with the nursing home group (40% and 28% respectively). More carers in nursing homes gave regular advice about oral care than the hospital-based nurses (54% and 43% respectively). Eighteen per cent of each group thought that edentulous individuals did not require regular oral care. Eighty-five per cent of hospital-based nurses and 95% of nursing home carers incorrectly thought that dentures were 'free' on the NHS. Although trends were observed between the two groups, no comparisons were statistically significant (Chi-square; level p < 0.05). CONCLUSIONS: Deficiencies exist in the knowledge of health care workers both in hospital and in the community setting, although the latter were less knowledgeable but more likely to give advice to older people.

Determination of the pH of peri-implant crevicular fluid in successful and failing dental implant sites: a pilot study.

The aims of this pilot study were to assess if a standard technique which is used to determine the pH of dental plaque around natural teeth (the 'touch electrode' technique) could be modified for use to determine the pH of crevicular fluid around dental implants, and to evaluate any possible changes in the peri-implant crevicular fluid pH in successful and failing implants. pH measurements of a sample of subjects' (n=17) peri-implant crevicular fluid of both successful and failing dental implants present in the same oral cavities were performed using iridium/iridium oxide (Beetrode) electrodes with 100 microm sensing tips, connected to an Orion 720 A pH meter. The technique appeared to be satisfactory for the purpose intended. The mean pH of the successful implants was 6.80 [STD+/-0.4; 95% confidence intervals (CI), 6.50-7.0], and that for the failing dental implants was 7.20 (STD+/-0.6; 95% CI, 6.90-7.50). The results showed that the technique described could be satisfactorily used to determine the pH of peri-implant crevicular fluid at dental implant sites, and that there was a significant difference between the pH of successful and failing dental implants (P<0.05). However, the results obtained should be interpreted with caution in view of the small sample size used in this pilot study.

Developments in dental plaque pH modelling.

OBJECTIVES: The objectives of this review were to give a comprehensive account of the methods used to determine dental plaque pH over the last 50 years, to review how these methods have been used in dental cariology research and to give an update as to how dental plaque pH studies might be developed in the future. DATA: Published, referred papers and abstracts of conference proceedings in the literature were reviewed. SOURCES: A comprehensive search of the electronic databases PubMed and Medline, was undertaken. In addition, a hand search of the Index Denticus was done to identify relevant citations before 1966. STUDY SELECTION: Relevant published literature in peer-reviewed publications was reviewed. No additional inclusion criteria were applied. CONCLUSIONS: This comprehensive review gives an account of the background to, history of, relative merits and demerits of, applications of and future of dental plaque pH technologies.

A study investigating the formation of artificial sub-surface enamel caries-like lesions in deciduous and permanent teeth in the presence and absence of fluoride.

OBJECTIVES: Clinical and in situ studies have shown that caries formation and progression is faster in primary than in permanent teeth. Ambient levels of fluoride are also known to influence the processes of carious lesion formation. The aims were, firstly to investigate the incidence of artificial sub-surface caries lesion formation in the enamel of deciduous and permanent teeth in vitro. Secondly, to compare quantitatively the mineral content and distribution of these lesions and assess the possible influence of fluoride upon the lesion parameters. METHODS: Twenty primary molars and 20 permanent premolars were randomly assigned to one of four experimental groups. Samples in each experimental group were immersed in a 0.05M lactic acid gel (6% w/v hydroxyethyl cellulose, pH 4.5) either in the absence or presence of fluoride for 7 days. Subsequently, lesion parameters of mineral loss (vol x % microm) and lesion depth (microm) were assessed by transverse microradiography and image analysis. RESULTS: No significant differences existed between the lesion parameters of permanent and primary teeth (P=0.20). Irrespective of tooth type, lesion parameters were significantly reduced in samples demineralised in the presence of fluoride (P< or =0.002). CONCLUSIONS: Fluoride significantly reduces the severity of sub-surface caries lesions formed in vitro and in contrary to previous studies, there were no significant differences in lesions parameters between permanent and primary teeth.

Implant complications and failures: the fixed prosthesis.

The implant-retained fixed prosthesis has been advocated as an effective restoration offering significant benefits over conventional prosthetics. The success of treatment depends on careful pre-surgical planning and prosthesis design. This paper outlines some common complications encountered during the planning, fabrication and maintenance of both large and small fixed prostheses and suggests how these complications can be minimized.