Shade matching quality among dental students using visual and instrumental methods

Objectives

Study aims were to compare shade matching quality between visual and machine-aided shade selection among dental students and to evaluate the effect of experience and gender.

Methods

A total of 204 undergraduates and interns participated. They were briefed about colour matching using a visual method with a Vita-3D Master system and a spectrophotometer. Participants with colour vision deficiency were excluded. Six maxillary anterior teeth of a maxillary blue stone cast were replaced with six maxillary artificial teeth. Participants selected the best shade match using each method. A daylight illuminator with the GTI mini-matcher colour viewing system was used during the test. The results were statistically analysed with SPSS version 19 with 95% confidence intervals. Frequencies and Chi-square tests were used to analyse the data, at α = 0.05 and with P < 0.05 indicating significance.

Results

Among the participants, 36.3% visually selected the correct shade, and 80.4% did so using the Easy Shade Compact machine. Experience (P = 0.177) and gender (P = 0.560) did not affect visual shade selection; in addition, with the Easy Shade Compact device, males and females equally mastered its use (P = 1.0), and experience did not influence outcomes (P = 0.552).

Conclusions

The shade matching device was significantly better than the conventional visual method. With both techniques, neither experience nor gender influenced shade matching quality.

Clinical significance

Visual tooth colour matching is unreliable and inconsistent because of various subjective and objective factors, and the use of a colour measuring device might improve the quality of shade matching among dental students.     

Effect of a 10% carbamide peroxide on wear resistance of enamel and dentine: In situ study

Objectives

This triple-blind, 2 × 2 crossover in situ study, was undertaken to verify whether the wear resistance of enamel and root dentine would be affected by bleaching with a 10% carbamide peroxide agent and a placebo agent.

Methods

Thirty slabs of each substrate (2 mm × 3 mm × 2 mm) were selected for each phase, after flattening and polishing procedures and microhardness test. After a 7-day lead-in period, one specimen of each substrate was randomly bonded on the facial surface of each one of 30 subject's upper second premolars. The volunteers received instructions on how to perform toothbrushing and application of gel in the tray. Fifteen volunteers bleached their maxillary arch with a 10% carbamide peroxide bleaching agent for a 2-week period, while the remainders used a placebo agent. After a 1-week washout period, a new set of enamel and root dentine slabs were bonded to the premolars and volunteers were crossed over to the alternate agent for 14 days. The resistance of enamel and root dentine to wear following bleaching, toothbrushing and intraoral exposure was measured with a profilometer, using reference areas.

Results

For enamel, ANOVA did not demonstrate significant difference between wear provided by placebo and bleaching agent (p = 0.3713), but higher wear depth was observed for bleached root dentine (p = 0.0346).

Conclusions

While overnight bleaching caused no alteration in wear resistance of enamel, root dentine showed increased tissue loss.     

Clinical risk factors related to failures with zirconia-based restorations: An up to 9-year retrospective study

Objectives

The first objective of this study was to retrospectively evaluate zirconia-based restorations (ZBR). The second was to correlate failures with clinical parameters and to identify and to analyse chipping failures using fractographic analysis.

Methods

147 ZBR (tooth- and implant-supported crowns and fixed partial dentures (FPDs)) were evaluated after a mean observation period of 41.5 ± 31.8 months. Accessorily, zirconia implant abutments (n = 46) were also observed. The technical (USPHS criteria) and the biological outcomes of the ZBR were evaluated. Occlusal risk factors were examined: occlusal relationships, parafunctional habits, and the presence of occlusal nightguard. SEM fractographic analysis was performed using the intra-oral replica technique.

Results

The survival rate of crowns and FPDs was 93.2%, the success rate was 81.63% and the 9-year Kaplan–Meier estimated success rate was 52.66%. The chipping rate was 15% and the framework fracture rate was 2.7%. Most fractographic analyses revealed that veneer fractures originated from occlusal surface roughness. Several parameters were shown to significantly influence veneer fracture: the absence of occlusal nightguard (p = 0.0048), the presence of a ceramic restoration as an antagonist (p = 0.013), the presence of parafunctional activity (p = 0.018), and the presence of implants as support (p = 0.026). The implant abutments success rate was 100%.

Conclusions

The results of the present study confirm that chipping is the first cause of ZBR failure. They also underline the importance of clinical parameters in regards to the explanation of this complex problem. This issue should be considered in future prospective clinical studies.

Clinical significance

Practitioners can reduce chipping failures by taking into account several risk parameters, such as the presence of a ceramic restoration as an antagonist, the presence of parafunctional activity and the presence of implants as support. The use of an occlusal nightguard can also decrease failure rate.     

Comparison of pattern of failure of resin composite restorations in non-carious cervical lesions with and without occlusal wear facets

Objectives

Many studies have reported the clinical problems associated with resin composite restorations in NCCLs. None has compared these clinical problems in NCCLs with and without occlusal wear facets. The present study sets out to determine the proportion of NCCLs that presents occlusal wear facets, and to compare the failure pattern of resin composite restorations in NCCLs with and without occlusal wear facets.

Methods

Teeth with NCCLs were classified into two groups, those with and without occlusal wear facets. Both groups were restored using micro hybrid resin composite. The restorations were evaluated at the end of 2 years concerning post-operative sensitivity, retention, marginal integrity, marginal discolouration, wear, and secondary caries, using the USPHS criteria. Statistical analysis compared the ratings of each criterion between the two groups using Pearson's χ² or Fisher's exact test.

Results

About one-third (33.8%) of teeth with NCCLs presented with occlusal wear facets, more NCCLs with occlusal wear facets in mandibular teeth (44.7%) than maxillary teeth (24.5%). Retention rate of composite resin restorations in NCCLs with and without occlusal wear facets was 63.9% and 74.4% respectively at the end of 2 years. More marginal discolouration and defects were observed in restorations in NCCLs with occlusal wear facets, the differences were not statistically significant (p > 0.05).

Conclusions

The decline in ratings of marginal discolouration and defects, and the lower retention rate of restorations in NCCLs with occlusal wear facets may support the role of occlusal stress and tooth flexure as a cause of failure of restorations in NCCLs.

Clinical significance

The ability to distinguish between stress induced lesions (with occlusal wear facets) and other cervical lesions will have important ramifications for the success of their restorations because they are not subjected to the same physical forces that are responsible for the deterioration of the restoration.     

Quantitative light-induced fluorescence (QLF): A tool for early occlusal dental caries detection and supporting decision making in vivo

Objectives

This study reports the development and assessment of a novel method using quantitative light-induced fluorescence (QLF), to determine whether QLF parameters ΔF and ΔQ were appropriate for aiding diagnosis and clinical decision making of early occlusal mineral loss by comparing QLF analysis with actual restorative management.

Methods

Following ethical approval, 46 subjects attending a dental teaching hospital were enrolled. White light digital (WL) and QLF images/analyses of 46 unrestored posterior teeth with suspected occlusal caries were made after a clinical decision had already been taken to explore fissures operatively. WL and QLF imaging/analysis were repeated after initial cavity preparation. The type of restorative treatment was determined by the supervising clinician independent of any imaging performed. Actual restorative management carried out was recorded as fissure sealant/preventive resin restoration (F/P) or class I occlusal restoration (Rest.) thus reflecting the extent of intervention (=gold standard). All QLF images were analysed independently.

Results

The results showed statistically significant differences between the two treatment groups ΔF (p = 0.002) (mean 22.60 – F/P and 28.80 – Rest.) and ΔQ (p = 0.012) (mean 230.49 – F/P and 348.30 – Rest.).

Conclusions

ΔF and ΔQ values may be useful in aiding clinical diagnosis and decision making in relation to the management of early mineral loss and restorative intervention of occlusal caries.

Clinical significance

QLF has the potential to be a valuable tool for caries diagnosis in clinical practice.     

Biocompatibility effects of indirect exposure of base-metal dental casting alloys to a human-derived three-dimensional oral mucosal model

Objectives

The study employed a three-dimensional (3D) human-derived oral mucosal model to assess the biocompatibility of base-metal dental casting alloys ubiquitous in fixed prosthodontic and orthodontic dentistry.

Methods

Oral mucosal models were generated using primary human oral keratinocyte and gingival fibroblast cells seeded onto human de-epidermidised dermal scaffolds. Nickel–chromium (Ni–Cr) and cobalt–chromium (Co–Cr) base-metal alloy immersion solutions were exposed to oral mucosal models for increasing time periods (2–72 h). Analysis methodologies (histology, viable cell counts, oxidative stress, cytokine expression and toxicity) were performed following exposure.

Results

Ni-based alloy immersion solutions elicited significantly decreased cell viability (P < 0.0004) with increased oxidative stress (P < 0.0053), inflammatory cytokine expression (P < 0.0077) and cellular toxicity levels (P < 0.0001) compared with the controls. However, the Ni-free Co–Cr-based alloy immersion solutions did not elicit adverse oxidative stress (P > 0.4755) or cellular toxicity (P < 0.2339) responses compared with controls.

Conclusions

Although the multiple analyses highlighted Ni–Cr base-metal alloy immersion solutions elicited significantly detrimental effects to the oral mucosal models, it was possible to distinguish between Ni–Cr alloys using the approach employed. The study employed a 3D human-derived full-thickness differentiated oral mucosal model suitable for biocompatibility assessment of base-metal dental casting alloys through discriminatory experimental parameters.

Clinical significance

Increasing incidences of Ni hypersensitivity in the general population warrants serious consideration from dental practitioners and patients alike where fixed prosthodontic/orthodontic dental treatments are the treatment modality involved. The novel and analytical oral mucosal model has the potential to significantly contribute to the advancement of reproducible dental medical device and dental material appraisals.     

Association between perceived oral and general health

Objectives

The aim of this study was to determine the magnitude of the association between perceived oral and general health-related quality of life (O/HRQoL) in the German general population and to compare it with the correlation of both constructs in dental patients.

Methods

OHRQoL was assessed using the OHIP-49 and HRQoL using the SF-36 in a sample (N = 811) representative of the adult general population of Germany (age: 18–99 years), and in a sample (N = 313) of consecutive adult dental patients at least 18 years of age seeking prosthodontic care or attending their annual checkup. Correlation between OHRQoL and HRQoL was computed using structural equation modelling-based confirmatory factor analysis and path analysis. Based on the correlation coefficients, the coefficients of determination (r²) were calculated.

Results

Correlation between OHRQoL and HRQoL after partialling out effects of age, gender and level of depression in general population subjects was rho = 0.28 resulting in an explanation of the variance of HRQoL by OHRQoL of 7.8%. In dental patients the correlation coefficient was somewhat lower (rho = 0.24) corresponding to an explanation of the variance of HRQoL by OHRQoL of 5.6%. Difference between correlation coefficients was not significant (p = 0.514).

Conclusion

Our findings provide evidence for the inseparable, intertwined relationship between perceived oral and general health.     

Immediate nonfunctional versus immediate functional loading and dental implant failure rates: A systematic review and meta-analysis

Objectives

The purpose of the present review was to test the null hypothesis of no difference in the implant failure rates, postoperative infection, and marginal bone loss for patients being rehabilitated using dental implants with immediate nonfunctional loading (INFL) compared to immediate functional loading (IFL), against the alternative hypothesis of a difference.

Methods

An electronic search without time or language restrictions was undertaken in March 2014. Eligibility criteria included clinical human studies, either randomized or not. The estimates of relative effect were expressed in risk ratio (RR) and mean difference (MD) in millimeters.

Results

1059 studies were identified and 11 studies were included, of which 7 were of high risk of bias, whereas four studies were of low risk of bias. The results showed that the procedure used (nonfunctional vs. functional) did not significantly affect the implant failure rates (P = 0.70), with a RR of 0.87 (95% CI 0.44–1.75). The wide CI demonstrates uncertainty about the effect size. The analysis of postoperative infection was not possible due to lack of data. No apparent significant effects of non-occlusal loading on the marginal bone loss (MD 0.01 mm, 95% CI -0.04–0.06; P = 0.74) were observed.

Conclusions

The results of this study suggest that the differences in occlusal loading between INFL and IFL might not affect the survival of these dental implants and that there is no apparent significant effect on the marginal bone loss.Clinical Significance: There has been a controversy concerning whether dental implants should be subjected to immediate functional or nonfunctional loading. As the philosophies of treatment may alter over time, a periodic review of the different concepts is necessary to refine techniques and eliminate unnecessary procedures. This would form a basis for optimum treatment.     

Preventive effect of an iron varnish on bovine enamel erosion in vitro

Objective

The aim of this study was to evaluate, in vitro, the effect of an experimental varnish containing iron on the dissolution of bovine enamel by carbonated beverage.

Methods

Eighty specimens were randomly allocated to four groups (n = 20 per group), according to the following treatments: Fe varnish (FeV, 10 mmol/L Fe), F varnish (FV, 2.71% F), placebo varnish (PV) and control (not treated, NT). The varnishes were applied in a thin layer and removed after 6 h. Then, the samples were submitted to six cycles, alternating re- and demineralisation (only 1 day). Demineralisation was performed with the beverage Coca-Cola^® (10 min, 30 mL/block) and remineralisation with artificial saliva for 1 h. In order to determine the amount of enamel dissolved, the wear was analysed by profilometry. Data were analysed by ANOVA and Tukey's test (p < 0.05).

Results

The mean wear (±S.E.) was significantly lesser for the FeV (0.451 ± 0.018 μm) when compared to the other treatments. The FV caused significantly less wear (0.554 ± 0.022 μm) when compared to PV (0.991 ± 0.039 μm) and NT (1.014 ± 0.033), which did not significantly differ from each other.

Conclusions

The results suggest that the iron varnish can interfere with the dissolution of dental enamel in the presence of acidic beverages.     

Influence of procedural variations during the laboratory phase of complete denture fabrication on patient satisfaction and denture quality

Objectives

To compare subjective and objective outcomes of complete dentures fabricated with standard clinical protocols, but omitted selected steps during the laboratory phase.

Materials and methods

Forty-three edentulous patients (mean age 58.1 years, SD 9.9, range 35–78), were consecutively recruited and randomly assigned to one of four groups according to selected variations of laboratory steps: Group 1 (n = 10), omission of secondary casts obtained from impressions in border moulded custom trays; Group 2 (n = 10), omission of secondary casts and face-bow articulator mounting; Group 3 (n = 10), omission of face-bow mounting; Group 4 (n = 13), no steps omitted (control). Clinical procedures for all groups were identical, and performed by senior dental students under supervision of prosthodontists, all of whom were blinded to the Group. At 1-, 4- and 12-weeks after delivery, patients rated their overall satisfaction, as well as a range of functional factors using visual analogue scales. An independent blinded prosthodontist similarly rated four domains of denture quality at the 1-week follow-up.

Results

No significant differences were noted among the groups in all aspects of patients’ assessments at all the time points (P > 0.1). There were no significant differences in prosthodontists’ ratings of denture quality in any of the domains examined (P > 0.1).

Conclusion

Selected omissions of steps (face-bow mounting and/or secondary casts) during the laboratory phase of complete denture fabrication has only a minor role, if any, in subjective and objective outcomes, contrasting with the common belief that such omissions will adversely affect outcomes.

Clinical significance

General practitioners provide most complete dentures. Many do not follow all the procedures they were taught at dental school. Our finding that omitting frequently advocated steps made no difference to patient satisfaction or to denture quality suggests that cost-effectiveness through simplifications be considered in practice and in education.     

Reduced wear of enamel with novel fine and nano-scale leucite glass-ceramics

Objectives

Leucite glass-ceramics used to produce all-ceramic restorations can suffer from brittle fracture and wear the opposing teeth. High strength and fine crystal sized leucite glass-ceramics have recently been reported. The objective of this study is to investigate whether fine and nano-scale leucite glass-ceramics with minimal matrix microcracking are associated with a reduction in in vitro tooth wear.

Methods

Human molar cusps (n = 12) were wear tested using a Bionix-858 testing machine (300,000 simulated masticatory cycles) against experimental fine crystal sized (FS), nano-scale crystal sized (NS) leucite glass-ceramics and a commercial leucite glass-ceramic (Ceramco-3, Dentsply, USA). Wear was imaged using Secondary Electron Imaging (SEI) and quantified using white-light profilometry.

Results

Both experimental groups were found to produce significantly (p < 0.05) less volume and mean-height tooth loss compared to Ceramco-3. The NS group had significantly (p < 0.05) less tooth mean-height loss and less combined (tooth and ceramic) loss than the FS group. Increased waviness and damage was observed on the wear surfaces of the Ceramco-3 glass-ceramic disc/tooth group in comparison to the experimental groups. This was also indicated by higher surface roughness values for the Ceramco-3 glass-ceramic disc/tooth group.

Conclusions

Fine and nano-sized leucite glass-ceramics produced a reduction in in vitro tooth wear. The high strength low wear materials of this study may help address the many problems associated with tooth enamel wear and restoration failure.     

Atmospheric moisture effects on the testing rate and cementation seating load following resin-strengthening of a soda lime glass analogue for dental porcelain

Objectives

To investigate if resin-cementation of a soda lime glass dental analogue could elucidate information regarding the pattern of resin-reinforcement when coated in an environment actively scavenged of moisture.

Methods

192 soda lime disc-shaped specimens (alumina particle air abraded, hydrofluoric acid-etched and silane coated) were randomly assigned to eight groups (n = 24 per group) prior to resin-coating at seating loads of 5 N (Groups A–D) and 30 N (Groups E–H) in an environment where moisture was actively scavenged and maintained below 15 ppm. Following one week storage the discs were tested in biaxial flexure at crosshead rates of 0.01, 0.1, 1 and 10 mm/min. Analysis of group means was performed utilising a general linear model univariate analysis and post hoc all paired Tukey tests (P < 0.05).

Results

The general linear model univariate analysis identified the mean biaxial flexure strength (BFS) was significantly influenced by the factors resin-cementation seating load (P < 0.001) and crosshead speed of the applied load (P < 0.001) with a significant interaction (P = 0.008) between both factors. The linear logarithmic regression curves fitted to the group mean BFS data plotted against the crosshead speed highlighted significant differences between the pattern of resin-strengthening for the cementation loads and testing conditions.

Conclusions

The decrease in resin-penetration expected within the ‘resin-ceramic hybrid layer’ following removal of the 30 N seating load was proposed as the modifying resin-strengthening parameter. These observations are supported by the viscoelastic and creep behaviour of resins at slow testing rates which becomes the dominant or determining phenomenon.     

The efficacy and safety of articaine versus lignocaine in dental treatments: A meta-analysis

Objectives

Although articaine has been recommended for providing an improved local anaesthetic effect in patients presenting for dental treatments, a relevant meta-analysis has been lacking. Despite articaine's popularity, there is contradictory evidence to support the claims. The aim of this systematic review was to compare the efficacy and safety of articaine with lignocaine in maxillary and mandibular infiltrations and block anaesthesia in patients presenting for routine dental treatments.

Data sources

The following databases were searched: Cochrane Central, Medline, Embase, and ProQuest Health and Medical Complete. In addition, the metaRegister of the controlled trials database was searched to identify dissertations and ongoing or unpublished trials, and the Australian division of Septodont (the manufacturer of articaine and lignocaine) was contacted. The bibliographies of identified articles were also searched.

Study selection

Inclusion was limited to: (1) randomized controlled trials in patients requiring non-complex routine dental treatments; (2) interventions comparing 4% articaine (1:100,000 epinephrine) with 2% lignocaine (1:100,000 epinephrine) for maxillary and mandibular infiltrations and block anaesthesia; and (3) with principal outcome measures of anaesthetic success, post-injection adverse events or post-injection pain. Trial quality was evaluated by assessing randomization, allocation concealment, blinding, intention to treat analyses and how losses to follow up were addressed. Treatment effects were combined by meta-analysis using the random effects method.

Results

Articaine is more likely than lignocaine to achieve an anaesthetic success in the posterior first molar area with a relative risk for success at 1.31 (95% CI 1.12–1.54, P = 0.0009). There is no difference in post-injection adverse events between articaine and lignocaine with a relative risk of 1.05 (95% CI 0.66–1.65, P = 0.85). However, articaine injection results in a higher pain score as measured by Visual Analogue Scale, than lignocaine at the injection site after anaesthetic reversal with a weighted mean difference of 6.49 (95% CI 0.02–12.96, P = 0.05) decreasing to 1.10 (95% CI 0.18–2.02, P = 0.02) on the third day after injection.

Conclusion

The results of this systematic review provide support for the argument that articaine is more effective than lignocaine in providing anaesthetic success in the first molar region for routine dental procedures. In addition, both drugs appear to have similar adverse effect profiles. The clinical impact of articaine's higher post-injection pain scores than lignocaine is negligible. Hence, articaine is a superior anaesthetic to lignocaine for use in routine dental procedures. Use in children under 4 years of age is not recommended, since no data exists to support such usage.     

Perceptibility and acceptability thresholds for colour differences in dentistry

Introduction

Data on acceptability (AT) and perceptibility thresholds (PT) for colour differences vary in dental literature. There is consensus that the determination of ΔE* is appropriate to define AT and PT, however there is no consensus regarding the values that should be used. The aim of this clinical review was to provide a systematic approach to the topic of colour science of high clinical relevance to dental research.

Materials and methods

MEDLINE/PubMed, WoS and EBSCO databases were searched up to January 7, 2013; the outcome was restricted to English, and to clinical studies were spectrophotometers were used for measurement.

Results

Forty-eight studies were eligible and met the inclusion criteria. Of the 48 studies there appeared to be a trend in their source references: 44% referred to the same study for the PT (ΔE* = 1); and 35% referred to the same article for the AT (ΔE* = 3.7).

Conclusions

More than half the studies defined PT as ΔE* = 1, and one third of the studies referred to ΔE* = 3.7 as the threshold at which 50% of observers accepted the colour difference. Most clinical studies refer to the same few in vitro literature that have attempted to determine PT and AT from decades ago.     

Association between the cariogenicity of a dental microcosm biofilm and its red fluorescence detected by Quantitative Light-induced Fluorescence-Digital (QLF-D)

Objective

This study evaluated whether Quantitative Light-induced Fluorescence-Digital (QLF-D) can detect the levels of cariogenicity of dental microcosm biofilms by assessing the red fluorescence intensity.

Methods

Dental microcosm biofilms were initiated from human saliva on bovine enamel discs. Biofilms with various levels of cariogenicity were then grown in artificial saliva supplemented with sucrose at different concentrations (0.05%, 0.1%, 0.2%, and 0.5%) in 24-well microplates. After 10 days, fluorescence images of the biofilms were captured by the QLF-D to analyse the red fluorescence intensity, which was quantified as the red/green ratio (R/G value). The supernatant pH was also measured, as well as the total and aciduric bacteria counts of the collected biofilms. Mineral loss in enamel was also evaluated by calculating the percentage of surface microhardness changes (%SHC).

Results

The R/G values of the biofilms differed significantly with the sucrose concentration (p < 0.0001), increasing consistently as the sucrose concentration increased from 0.05% (=0.91) to 0.5% (=2.56). Strong correlation was identified between the R/G value and the number of aciduric bacteria (r = 0.83, p < 0.0001), supernatant pH (r = −0.95, p < 0.0001), and %SHC (r = 0.90, p < 0.0001).

Conclusions

The red fluorescence as observed by the QLF-D was correlated with the cariogenic properties of dental microcosm biofilms in vitro, which indicates that this device can be used to detect the levels of cariogenicity of a dental biofilm.

Clinical significance

The QLF-D is able to assess the cariogenic levels of dental plaque based on the intensity of red fluorescence.     

Monitoring the maturation process of a dental microcosm biofilm using the Quantitative Light-induced Fluorescence-Digital (QLF-D)

Objective

The aim of this study was to investigate whether Quantitative Light-induced Fluorescence-Digital (QLF-D) could monitor the degree of maturation of dental microcosm biofilms by observing the red fluorescence emitted from the biofilms.

Methods

Dental microcosm the biofilms were grown on bovine enamel discs. They were initiated from human saliva, and then grown in 0.5% sucrose growth media for 10 days. On days 1, 2, 3, 7, and 10 after the inoculation, fluorescence images of the biofilms were captured using the QLF-D and the red fluorescence intensity was quantified by calculating the red/green ratio (R/G value). Total and aciduric bacteria within the biofilms were counted, and the degree of demineralization was evaluated by measuring the percentage of surface microhardness change (ΔVHN) and lesion depth in the enamel.

Results

The R/G values of the biofilms assessed by the QLF-D increased significantly over time up to 7 days after inoculation (p < 0.0001). The R/G values showed significant positive correlations with the total bacterial CFUs (r = 0.74, p = 0.001), aciduric bacterial CFUs (r = 0.85, p = 0.001), ΔVHN (r = 0.65, p = 0.001), and lesion depth in the enamel (r = 0.82, p = 0.001) according to the maturation time.

Conclusions

The red fluorescence detected by the QLF-D increased according to biofilm maturation and was significantly associated with the cariogenicity of the biofilm. Therefore, this device could be used to monitor the degree of biofilm maturation by observing the red fluorescence emitted from cariogenic biofilms.

Clinical significance

The QLF-D enables the detection of a mature dental plaque and monitoring of its cariogenic status by observing the plaque fluorescence non-destructively, in real time.     

The effect of casein phosphopeptide–amorphous calcium phosphate on erosive enamel and dentine wear by toothbrush abrasion

Objective

In addition to its role as a remineralizing agent in preventing dental caries, calcium product (CPP–ACP) delivered as a mousse (Tooth Mousse^®, TM) can reduce erosion of enamel and dentine. The aim of this study was to determine whether CPP–ACP could also reduce erosive tooth wear involving toothbrush abrasion.

Methods

Flat, polished enamel and dentine specimens (n = 72) were subjected to 10 wear regimes, with each regime involving erosion in 0.3% citric acid (pH 3.2) for 10 min followed by toothbrush abrasion in a slurry of fluoride-free toothpaste and artificial saliva (1:3 ratio by weight) under a load of 2N for 200 cycles. The specimens were immersed in artificial saliva for 2 h between wear regimes. In the experimental group 1, TM (containing CPP–ACP) was applied at the beginning of each wear episode for 5 min whereas TM− (without CPP–ACP) was applied in the experimental group 2. No mousse was applied in the control group.

Results

TM significantly reduced enamel wear (mean ± S.E., 1.26 ± 0.33 μm in the experimental group 1 vs 3.48 ± 0.43 μm in the control group) and dentine wear (2.16 ± 0.89 μm in the experimental group 1 vs 10.29 ± 1.64 μm in the control group), and dentine wear was significantly less in the experimental group 1 than in the experimental group 2 (5.75 ± 0.98 μm).

Conclusion

The finding that TM reduced erosive tooth wear involving toothbrush abrasion, probably by remineralizing and lubricating eroded tooth surfaces, may have implications in the management of tooth wear.     

Three-dimensional fit of lithium disilicate partial crowns in vitro

Objectives

A novel three-dimensional scanning technique was used to investigate the effects a one-step and a two-step impression methods can have on the three-dimensional fit of ceramic partial crowns.

Methods

An acrylic model of a mandibular first molar was prepared to receive a partial coverage all-ceramic crown (mesio-occlusal-distal inlay preparation with reduction of all cusps and rounded shoulder finish line of buccal wall). Type IV plaster replicates were cast based on one-step single viscosity (OS/SV), one-step dual viscosity (OS/DV), and two-step dual viscosity (TS/DV) impressions. Five partial crowns were fabricated per impression method using hot-pressed lithium disilicate ceramics. Then, preparation and restorations were digitized using a non-contact, white-light scanner featuring self-calibrating optics (overall measurement uncertainty of <5 μm). Data were entered into quality inspection software which superimposed the records (best-fit-algorithm), calculated fit-discrepancies for every pixel, and colour-coded the results to aid visualization. Furthermore, mean quadratic deviations (RMS) were computed and analyzed statistically with a 1-way ANOVA. Scheffé’s procedure was applied for multiple comparisons (α = 0.05).

Results

Mean RMS-values for marginal (internal) surfaces were: OS/SV 70 (20) μm, OS/DV 78 (34) μm, and TS/DV 107 (52) μm. Differences among impression techniques were statistically significant at p = 0.006 (0.001). Qualitatively, occlusal ridges and preparation finish lines were over contoured, whereas inner occlusal boxes and the proximal–occlusal isthmus were under contoured.

Conclusions

OS/SV and OS/DV impressions resulted in statistically significantly smaller marginal and internal discrepancies than the two-step technique.

Clinical significance

Marginal and internal fit of hot-pressed lithium disilicate partial crowns depended on the employed impression technique. One-step impressions are preferred over two-step techniques in many day-to-day clinical situations, especially for the fabrication of partial coverage crown restorations.     

Changes in oral health related quality of life after dental bleaching in a double-blind randomized clinical trial

Objectives

This study aimed to assess changes in oral health-related quality of life (OHRQoL) in individuals enroled in a double-blind randomized clinical trial conducted to evaluate the efficacy and safety of two carbamide peroxide concentrations used in at-home vital bleaching in the city of Pelotas, Southern Brazil.

Methods

Ninety-two volunteers with a shade mean of C1 or darker for the six maxillary anterior teeth were randomized into two balanced groups (n = 46) according to bleaching agent concentration: 10% or 16% carbamide peroxide. The patients were instructed to use the whitening agent in a tray for 2 h once a day for three weeks. To assess changes in OHRQoL, participants completed the oral impact on daily performance (OIDP) at the start and one week after the completion of treatment. Because there was no difference with regard to whitening effect or tooth sensitivity during or after treatment the two groups were merged for the analyses of the current article. Before-and-after changes in OIDP scores were assessed by chi-square and McNemar tests (p < 0.05).

Results

Mean pre- and post-treatment OIDP scores varied from 0.42 to 0.60. When the frequency of impacts for different activities were compared, there was an increase in difficulty in cleaning teeth (p = 0.02) and a significant reduction in smiling and showing teeth with embarrassment (p = 0.03). Regarding the symptoms and main oral conditions that generated impact, there was higher number of participants reporting pain (p = 0.05) after treatment. In opposite, significant decrease was observed in individuals reporting being unhappy with their appearance (p = 0.03). On the contrary, it was showed a decrease in impacts resulting from dental colour was observed after bleaching (p = 0.03).

Conclusion

Quality of life is complex and encompasses different domains. Although positive impact of the dental bleaching was detected, with patients showing more their teeth without embarrassment, difficult in dental hygiene and pain resulting from the treatment were also reported, and this can negatively impact daily performances. Dentists must consider these aspects when performing aesthetics procedures.     

Intake of dairy products and the prevalence of dental caries in young children

Objectives

In vitro studies show that milk or milk components may have cariostatic properties. However, the results of epidemiological studies on the association between intake of dairy products and dental caries have been inconsistent. The purpose of this cross-sectional study was to examine the association between intake of dairy products and the prevalence of dental caries in young children.

Methods

Study subjects were 2058 Japanese children aged 3 years. Information on diet was assessed with a self-administered brief diet history questionnaire for children. The consumption of dairy products was categorized into 3 levels in order to represent the tertiles as closely as possible. Dental caries was assessed by a visual examination. Adjustment was made for sex, toothbrushing frequency, use of fluoride, between-meal snack frequency, maternal smoking during pregnancy, environmental tobacco smoke exposure at home, and paternal and maternal educational levels.

Results

Compared with yogurt consumption at the lowest tertile (<1 time/week), its intake at the highest level (≥4 times/week) was significantly associated with a lower prevalence of dental caries, showing a clear dose–response relationship (adjusted prevalence ratio = 0.78, 95% confidence interval: 0.62–0.98, P for trend = 0.04). There were no material associations between intake of cheese, bread and butter, or milk and the prevalence of dental caries.

Conclusions

These data suggest that a high consumption of yogurt may be associated with a lower prevalence of dental caries in young children.