H.P. Chew

Clinical Studies of Dental Erosion and Erosive Wear

We define erosion as apartial demineralisation of enamel or dentine by intrinsic or extrinsic acidsand erosive tooth wear as the accelerated loss of dental hard tissue through the combined effect of erosion and mechanical wear (abrasion and attrition) on the tooth surface. Most experts believe that during the last decade there has been a significant increase in the prevalence and severity of erosive tooth wear, particularly in adolescents. Even when erosive wear occurs in its milder forms, this is a matter of concern, as it may compromise the integrity of an otherwise healthy dentition in later life. The erosive wear process is complicated and modified by many chemical, behavioural and associated processes in the mouth. If interventions are to be developed it is therefore important that in vivo methods are developed to assess the outcomes of the erosion and erosive wear processes and the effects of interventions upon them. This paper discusses potential methods of investigating erosion and erosive wear in vivo and the difficulties associated with clinical studies.

Measuring initial enamel erosion with quantitative light-induced fluorescence and optical coherence tomography: an in vitro validation study.

Background: Measurement of initial enamel erosion is currently limited to in vitro methods. Optical coherence tomography (OCT) and quantitative light-induced fluorescence (QLF) have been used clinically to study advanced erosion. Little is known about their potential on initial enamel erosion. Objectives: To evaluate the sensitivity of QLF and OCT in detecting initial dental erosion in vitro. Methods: 12 human incisors were embedded in resin except for a window on the buccal surface. Bonding agent was applied to half of the window, creating an exposed and non-exposed area. Baseline measurements were taken with QLF, OCT and surface microhardness. Samples were immersed in orange juice for 60 min and measurements taken stepwise every 10 min. QLF was used to compare the loss of fluorescence between the two areas. The OCT system, OCS1300SS (Thorlabs Ltd.), was used to record the intensity of backscattered light of both areas. Multiple linear regression and paired t test were used to compare the change of the outcome measures. Results: All 3 instruments demonstrated significant dose responses with the erosive challenge interval (p < 0.05) and a detection threshold of 10 min from baseline. Thereafter, surface microhardness demonstrated significant changes after every 10 min of erosion, QLF at 4 erosive intervals (20, 40, 50 and 60 min) while OCT at only 2 (50 and 60 min). Conclusion: It can be concluded that OCT and QLF were able to detect demineralization after 10 min of erosive challenge and could be used to monitor the progression of demineralization of initial enamel erosion in vitro.

Unusual multiple production of N-acylhomoserine lactones a by Burkholderia sp. strain C10B isolated from dentine caries

Bacteria realize the ability to communicate by production of quorum sensing (QS) molecules called autoinducers, which regulate the physiological activities in their ecological niches. The oral cavity could be a potential area for the presence of QS bacteria. In this study, we report the isolation of a QS bacterial isolate C10B from dentine caries. Preliminary screening using Chromobacterium violaceum CV026 biosensor showed that isolate C10B was able to produce N-acylhomoserine lactones (AHLs). This bacterium was further identified as a member of Burkholderia, an opportunistic pathogen. The isolated Burkholderia sp. was confirmed to produce N-hexanoyl-L-homoserine lactone (C6-HSL), N-octanoyl-L-homoserine lactone (C8-HSL), N-decanoyl-L-homoserine lactone (C10-HSL) and N-dodecanoyl-L-homoserine lactone (C12-HSL).

Influence of the loci of non-cavitated fissure caries on its detection with optical coherence tomography

OBJECTIVE The main objective of this study was to evaluate the accuracy of optical coherence tomography (OCT) in detecting naturally occurring non-cavitated fissure caries (NCFC) in totality and at different loci by visually assessing cross-sectional OCT scans (B-scan) with an interpretation criterion. The secondary objective was to evaluate the agreement between dimensions of NCFC measured with OCT and polarized light microscopy (PLM). METHODS 71 investigation sites of sound fissure and naturally occurring NCFC on human extracted premolars were identified and scanned with a swept-source OCT. The teeth were then sectioned bucco-lingually at the investigation sites and imaged using PLM. Two calibrated examiners trained on the B-scan NCFC visual interpretation criteria established for this study, assessed the investigation sites and results were validated against PLM. RESULTS Detection sensitivity of B-scan for NCFC when fissures were assessed in totality, or on the slopes or walls separately are 0.98, 0.95, 0.94 and specificity are 0.95, 0.90, and 0.95. One-way ANOVA showed that width measurements of wall loci done with OCT and PLM were not statistically different. However, OCT height measurements of slope loci were statistically bigger with a constant bias of 0.08 mm (of which is not clinically significant) and OCT height measurements of wall loci were statistically smaller (0.57 mm) and Bland-Altman plots indicated presence of proportionate bias. CONCLUSION Visual assessment of B-scans with the interpretation criteria resulted in both high specificity and sensitivity and were not affected by loci location. OCT width measurement of wall loci is in agreement with PLM. CLINICAL SIGNIFICANCE Unanimous high sensitivity in this and previous studies indicate that visual assessment of B-scans reliably rule out NCFC. Detection accuracy was not affected by loci location. Width of wall loci and/or height of slope loci in OCT B-scan are to be used for monitoring NCFC but not height of wall loci.

General and erosive tooth wear of 16-year-old adolescents in Kuantan, Malaysia: prevalence and association with dental caries

BackgroundThe objective of this study was to determine the prevalence and severity of general tooth wear (GTW), i.e. tooth wear irrespective of etiology and erosive tooth wear (ETW), i.e. tooth wear predominantly due to erosion; and also to investigate the relationship between ETW and dental caries experience in 16-year-old adolescents in Kuantan, Malaysia.MethodsA multi-staged cluster sampling method was employed. A total of 598 16-year-old adolescents participated in this study. Participants’ demographic profile was assessed through a self-administered questionnaire. Clinical examinations were carried out under standardized conditions by a single examiner. The level of GTW was recorded using the modified Smith and Knight’s Tooth Wear Index (TWI) whilst ETW were recorded using the Basic Erosive Wear Examination (BEWE) index. This index was developed to record clinical findings and assist in the decision-making process for the management of erosive tooth wear. Dental caries was recorded using the D3MFT index whereby D3 denotes obvious dental decay into dentine detected visually.ResultsThe prevalence of GTW, ETW and dental caries, i.e. percentage of individuals found to have at least one lesion, was 99.8%, 45.0% and 27.8% respectively. Two thirds of affected teeth with GTW were observed to have a TWI score of 1 whereas almost all of the affected teeth with ETW had a BEWE score of 2. The mean D3MFT was 0.62 (95% CI 0.50, 0.73) with Decayed (D) teeth being the largest component, mean D3T was 0.36 (95% CI 0.30, 0.43). There was no significant association between socio-demographic factors and prevalence of ETW. Logistic regression analysis also showed no significant relationship between the prevalence of ETW and D3MFT (p > 0.05).ConclusionsAlmost all adolescents examined had GTW but they were mainly early lesions. However, nearly half were found to have ETW of moderate severity (BEWE score 2). No significant relationship between the occurrence of erosive tooth wear and caries was observed in this population.