Association between salivary characteristics and tooth wear: A systematic review and meta-analysis

OBJECTIVE

Literature was systematically reviewed to identify salivary characteristics and their association with tooth wear.

DATA

A protocol was developed a priori (PROSPERO CRD42022338590). Established systematic review methods were used for screening, data extraction, and synthesis. Risk of bias and the certainty of evidence were assessed using the JBI tools and GRADE, respectively. Direct and indirect association between tooth wear and salivary components and characteristics were assessed.

SOURCES

MEDLINE, Embase, SCOPUS, Web of Science, CINAHL, and additional sources were searched.

STUDY SELECTION

Studies reporting salivary characteristics in patients with tooth wear or models thereof were included. Animal and in-vitro studies and case reports were excluded.

RESULTS

One-hundred eleven studies were included. Qualitative analyses showed a negative association between tooth wear and salivary pH and flow rate in many studies. The higher the study size the higher the chances that an association with pH and flow rate was found. Xerostomia, buffer capacity and salivary consistency/viscosity had also some degree of association with tooth wear in fewer studies. Associations with the 39 salivary components were scarcer. Random effects meta-analyses (7 studies) showed that pH levels in stimulated whole saliva were lower in patient with tooth wear compared to controls (-0.07 [-0.10 to -0.04]). However, there was not enough evidence to establish a quantitative association with flow rate. The general risk of bias was unclear and the certainty of evidence was low or very low. A large diversity of methodologies limited the inclusion of all studies in quantitative synthesis.

CONCLUSION

From all potential risk factors, stimulated whole saliva pH showed a negative association, both quantitatively and qualitatively with tooth wear, indicating potential usefulness of pH monitoring in these patients. Moreover, associations between flow rate and tooth wear were observed qualitatively. However, in both cases the risk of bias was mostly unclear, and the certainty of evidence was low. No causal associations could be observed.

CLINICAL SIGNIFICANCE

Tooth wear is a prevalent condition that may lead to functional or esthetic impairments and pain. Knowing the potential risk factors like salivary pH or flow rate and their dynamics could be relevant during tooth wear monitoring and to intervene accordingly, especially in conditions like gastroesophageal reflux disease.

Developing diagnostic criteria for tooth wear, a preliminary beta version based on expert opinion, and a narrative literature review

BACKGROUND

Tooth wear is a multifactorial condition, leading to the irreversible loss of dental hard tissues. The availability of an unambiguous, universally applicable assessment protocol remains lacking.

OBJECTIVES

The goal of the authors is to develop a set of diagnostic criteria for the assessment of tooth wear (DC-TW). A two-step approach will be used to achieve this objective: (1) to develop a preliminary beta version of the DC-TW, based on the authors' clinical experience and their shared expertise and supported by a narrative review of the existing literature, and (2) to develop the final DC-TW, with input from a larger group of experts using an international Delphi process. This paper relates to the first step.

METHODS

The authors outlined the components that should be incorporated into the DC-TW. The literature search was performed to investigate if their concept was in line with the available literature. The search was conducted to identify eligible publications from inception to July 11, 2022. Two authors independently screened all publications, and differences in judgements were resolved through a consensus procedure.

RESULTS

The search yielded 5362 publications, resulting in the final inclusion of 383. These publications were divided into four main topics: (1) nomenclature/taxonomies; (2) self-report tools; (3) clinical assessment tools; and (4) clinical decision-making.

CONCLUSIONS

The information from the publications was used and fused with the clinical experience and shared expertise of the authors to contribute to the development of a preliminary beta version of the DC-TW.

Long term clinical performance of 'open sandwich' and 'total-etch' Class II composite resin restorations showing proximal deterioration of glass-ionomer cement

OBJECTIVES

To compare clinical performance of resin composite posterior Class-II restorations placed with etch-and-rinse adhesive or open sandwich technique using glass-ionomer cement.

METHODS

Data on Class II restorations placed by one dentist between 1990 and 2016 were collected from patient files, including caries risk, tooth related variables, applied materials and dates of last check-up visit and restoration placement. Open sandwich restorations were placed before 2001, while after 2001, a total-etch technique using etch-and-rinse 3-step adhesive was used when placing a Class II composite restoration. For statistical analysis, Kaplan-Meier statistics and a multilevel Cox-Regression was conducted (p < 0.05). Annual Failures Rates (AFR) were calculated.

RESULTS

675 Class II restorations were placed in 91 patients, 491 total-etch restorations (observation time 2-18 y), and 184 open sandwich restorations (observation time 19-29 y) showing AFRs at 15 years as 2.9 % for total-etch and 9.7 % for open sandwich restorations. Secondary caries as failure was equally distributed among the 2 groups and 27 % of the failures in the open sandwich group were due to proximal deterioration of glass-ionomer cement. The Cox-regression showed a significant higher risk for failure for the open sandwich technique compared to total-etch class-II composite restorations (HR = 2.9; p < 0.001).

SIGNIFICANCE

Application of glass-ionomer cement using the open sandwich technique cannot be recommended for class-II restorations as being more complex and showing poorer clinical performance.

Perception of oral health related quality of life and orofacial aesthetics following restorative treatment of tooth wear: A five-year follow-up

OBJECTIVES

Non-carious tooth wear often has a multifactorial etiology and may lead to functional or aesthetically related problems. The most common complaints associated with tooth wear are dissatisfaction with dental appearance and a negative impact on the experienced Oral Health Related Quality of Life (OHRQoL). The aim of this study was to investigate the change in OHRQoL and the perception of aesthetics, following restorative treatment of moderate to severe tooth wear patients, with a five-year follow-up.

METHODS

An explorative study, based on prospective data, was performed. OHRQoL and the perception of aesthetics were measured with the OHIP-NL and OES-NL. These questionnaires were completed before treatment, one month after treatment, and at 1-, 3- and 5-years post-treatment. Treatment involved full mouth reconstruction with composite resin restorations. The data was analysed as repeated measures by using a linear mixed-effects model.

RESULTS

One hundred and twenty-three tooth wear patients that received restorative rehabilitation were included (97 males, 26 females, 37.5 ± 8.8 years-old). Data showed a statistically significant increase in both experienced OHRQoL and orofacial appearance after restorative treatment. The OHIP-scores remained stable over time, while the OES-scores slightly decreased during the years after treatment. Regarding the seven domains of the OHIP, the largest difference in OHIP-score was found in the domain of 'Psychological Discomfort'. The mean overall OHIP-score was 1.8 at baseline and 1.3 at the 5-years recall. The mean OES score increased from 41.8 at baseline to 66.1 at the 5-years follow-up.

CONCLUSIONS

Tooth wear patients reported significant improvements in their OHRQoL and their perception of orofacial aesthetics after restorative treatment. This increase remained at least five years post-treatment.

CLINICAL SIGNIFICANCE

The clinical impact of restorative treatment for tooth wear patients is considerable. This paper emphasizes the need to include a discussion of the patient related outcome measures when planning care.

The longevity of tooth-coloUred materials used for restoration of tooth wear: an evidence-based approach

Patients with tooth wear are commonly encountered in general dental practice. When indicated, restorative rehabilitation is often accompanied by a request from the patient for an aesthetic, tooth-coloured outcome. This article seeks to provide an evidence-based approach, focussing on the longevity of the materials which can be used for the restorative treatment of tooth wear, as well as their modes of failure and observed performance.

[Restorative treatment of generalized tooth wear]

A 24-year-old patient with generalized tooth wear was referred to the Radboud Tooth Wear Project. The tooth wear had a chemical aetiology, caused by gastro-oesophageal reflux and resulting in functional problems of the masticatory system and a reduced quality of life. The treatment of the patient was minimally invasive, with directly applied composite restorations on all teeth, by means of which an increase of vertical dimension of occlusion was introduced. The restorative treatment was not preceded by testing of the new vertical dimension of occlusion. The patient was able to function well again after restorative treatment.

Randomised controlled trial on testing an increased vertical dimension of occlusion prior to restorative treatment of tooth wear

BACKGROUND

Evaluation of a new vertical dimension of occlusion (VDO) in complex restorative treatments is considered a necessary step prior to placement of restorations.

OBJECTIVES

This randomised controlled trial (RCT) aimed to assess the effects of using an evaluation of a VDO increase before restorative treatment in patients with moderate-to-severe tooth wear, on OHRQoL, freeway space (FWS) and interventions to restorations.

METHODS

Forty-two patients with tooth wear were included and randomly allocated to either a test phase with a Removable Appliance (RA) or no test phase. Restorative treatment consisted of restoration of all teeth using composite restorations in an increased VDO. OHIP-score, freeway space (FWS) and clinical acceptability of restorations were assessed at baseline and at recall appointments (1 month and 1 year). Intervention to restoration was scored in case of material chipping or when the abutment tooth had increased sensitivity that could be linked to occlusal overloading. ANCOVA analyses, Univariate Cox regression, t-tests and descriptive analyses were performed (p < .05).

RESULTS

Clinical follow-up after 1 year was completed for 41 patients. No significant effect of testing the VDO with a RA could be found on the OHIP-score (p = .14). Reduction of FWS in the RA group, compared to the control group, was significantly lower at 1 year (p = .01, 95% CI -1.09 to -0.15). No effect on early interventions to restorations was found (p = .94).

CONCLUSION

This RCT showed that a removable appliance is not indicated to functionally test the increased VDO prior to restorative treatment in patients with tooth wear.

Managing tooth wear with respect to quality of life: an evidence-based decision on when to intervene

Patients with more severe forms of tooth wear may require restorative rehabilitation. The decision to commence treatment must be taken carefully and there are a multitude of factors to consider. Alongside the clinical signs and symptoms typically associated with tooth wear, there is also the need to assess the impact of the condition on the patient's oral health-related quality of life. As part of the discussions relating to the attainment of informed consent for the restoration of the worn dentition, not only is it relevant to appropriately appraise the risks, benefits, costs, reasonable alternatives and likely prognosis of the proposed treatments, but to also elaborate on the expected impact of the intervention on the patient's oral health-related quality of life. The aim of this article is to review the evidence relating to the impact of the quality of life with the management of tooth wear, with the introduction of the concept of an evidence-based approach to decision-making when planning care.

Monitoring of erosive tooth wear: what to use and when to use it

Although we are increasingly recognising the need to assess patients for accelerated rates of tooth wear progression, it is often difficult to do so within a feasible diagnostic window. This paper aims to provide evidence-based timelines which a diagnosing clinician can expect to assess tooth wear progression in study models, clinical indices, clinical photographs and visually with intraoral scans. It also discusses new technologies emerging for the quantitative assessment of tooth wear, timelines for diagnosis, and caveats in the 3D scan registration and analysis process.

Posterior Dahl: A Minimally Invasive Method for the Treatment of Localized Posterior Tooth Wear

PURPOSE

This retrospective case series of 9 patients aimed to describe clinical outcomes and patient satisfaction following the implementation of the posterior Dahl concept to manage localized posterior tooth wear.

MATERIALS AND METHODS

Localized occlusal space was created in the posterior dentition. Supra-occluding direct restorations were placed bilaterally for the restoration of molars. Intraoral scans were taken at the pre-treatment stage, immediately post-restoration, and during follow-up appointments. Scans were used to undertake analysis of any occlusal changes and re-establishment of the occlusion. A questionnaire was used to assess patient satisfaction, alleviation of any pre-treatment concerns, and evaluation of post-treatment complaints.

RESULTS

Immediately post-treatment, all patients showed an increase in the vertical dimension. Opening of the bite in the untreated areas following restoration of worn posterior molars resulted either in a tendency towards or the actual reestablishment of the occlusion. One patient completely lacked compensatory vertical tooth movement in the untreated areas, culminating in the persistence of a vertical open bite. One restoration displayed cohesive fracture after 4 months. Pre-treatment problems (eg, sensitivity) were fully resolved amongst all patients after 6 months. Post-treatment complaints were minor and demonstrated resolution within a relatively short period of time. Eight patients reported being "very satisfied" with their treatment outcomes.

CONCLUSION

Application of the posterior Dahl concept appears to offer a promising, relatively simple, minimally invasive and effective approach for the management of localized posterior tooth wear, which is well accepted by patients.

[Measuring tooth wear with regular intra-oral 3D scanners: for still in the future, or is it already possible?]

Quantitative tooth wear measurement is a method of increasing importance when measuring tooth wear progression. The Radboud university medical center has developed a protocol that measures height and volumetric differences on regular 3D-scans. Intra-oral scans were made on patients with tooth wear and superimposed. To assess reliability the precision , as well as intra- and inter-rater precision of the protocol was tested. T-tests were performed to determine the structural and random error. Our findings indicate that the method is precise enough to measure height differences in patients with severe tooth wear progression, or tooth wear with an interval longer than 1 year. The method is not precise enough to measure volumetric changes.

Deterioration of anterior resin composite restorations in moderate to severe tooth wear patients: 3-year results

OBJECTIVES

Deterioration in anterior resin composite restorations placed in tooth wear patients was investigated after 36 months.

MATERIALS AND METHODS

Data collected prospectively for 47 participants of the Radboud Tooth Wear Project were used (41 ± 8 years, 90% male, n = 270 restorations). Restorations were individually evaluated using intraoral photographs and 3D scans to rate modified FDI scores and to record the presence of degradation features. Four groups with distinct combinations of composites and techniques were assessed, and multivariable logistic regression models were used to analyze the data (p < 0.05).

RESULTS

For all groups together, early degradation signs were present at 1 month: irregularities (41.5%) and ditching (7.4%) were observed at the surface and adhesive interfaces. The frequency of irregularities decreased in the 36-month evaluation (37%), but ditching (12.2%) and fractures (10.7%) were more common. The most frequent deterioration (based on photographs) was observed for staining (44%) and loss of luster (31%). In 3D scans, the most frequent were for wear (25%), marginal adaptation (24%), and the presence of irregularities (19%). Canines had 5.5 times more chances of deterioration by ditching than incisors (p < 0.001). The differences between composites and restorative techniques were minor.

CONCLUSIONS

A continuous degradation process of restorations placed in tooth wear patients was observed in anterior teeth restored with different composites, with a progression of the deterioration over 36 months.

CLINICAL RELEVANCE

When placing anterior resin composite restorations in tooth wear patients, it could be important to establish realistic expectations and the need for checkup appointments.

Rehabilitation of Worn Dentition with CAD-CAM Restorations: A Case Report

PURPOSE

To describe the digital workflow applied for restoring a severely worn dentition with minimally invasive CAD/CAM resin nano-composite restorations.

MATERIALS AND METHODS

A 40-year-old male in good general health and with full-arch dentition suffered from dentin hypersensitivity and wanted to improve the esthetics of his worn anterior teeth. The dental wear can be described as general, grade 3, according to the Tooth Wear Index,27 with more wear in maxillary than in mandibular teeth. Signs and symptoms were typical for a chemical type of wear, with some mechanical wear also apparent. No functional problems, eg, impaired chewing, were present. On the OHIP-49 questionnaire, the patient expressed a reduced quality of life. The goal of the treatment was to reconstruct the anatomical form of the teeth as far as possible, thereby also improving quality of life. Due to the rather large volume of lost tooth tissue per tooth, indirect treatment using CAD/CAM resin nano-composite restorations (LAVA Ultimate, 3M Oral Care) was applied.

RESULTS

The seating of the CAD/CAM resin nano-composite restorations (LAVA Ultimate, 3M Oral Care) restorations was considered precise.

CONCLUSION

In the treatment of severe tooth wear, the described digital workflow using CAD/CAM restorations for occluding restorations and direct composite materials in the esthetic zone is a potential treatment modality that is workable and minimally invasive.

Prospective Study on CAD/CAM Nano-Ceramic (Composite) Restorations in the Treatment of Severe Tooth Wear

PURPOSE

The aim of this prospective study was to evaluate the clinical performance of minimally invasive, CAD/CAM nano-ceramic (composite) restorations in patients with severe tooth wear, the effect of the restorative treatment on the oral health-related quality of life (OHRQoL), and the etiology of tooth wear as a risk factor for restoration failure.

MATERIALS AND METHODS

Patients with generalized severe tooth wear were included. Restorations (LAVA Ultimate, 3M Oral Care) were cemented (RelyX Ultimate, 3M Oral Care) on all teeth and were evaluated after 1 month and 1 year. OHRQoL was assessed via questionnaires at baseline and after 1 year. Differences were evaluated (paired t-test). Two mechanical tooth-wear lesions resulting from tooth-tooth contact, and 3 chemical tooth wear lesions resulting from intrinsic or extrinsic acids dissolving natural hard tooth substance, were evaluated to assess the etiology of tooth wear in association with restoration failure using multilevel logistic regression analyses (p < 0.05).

RESULTS

Twenty-one patients (age: 41.7 ± 10.4 years) were evaluated after 1 year (13.5 ± 1.2 months). 568 indirect CAD/CAM restorations were placed. None were replaced or lost. Twelve were repaired and 10 were refurbished. Success rates were 100% to 97.2%. Questionnaires showed a significant positive impact of the treatment on OHRQoL (p < 0.001). The presence of mechanical lesions did not pose a higher risk for restoration failure (p = 0.78). The presence of chemical lesions showed a lower risk of restoration failure (p = 0.002).

CONCLUSION

The use of minimally invasive, CAD/CAM nano-ceramic (composite) restorations in the restorative treatment of severely worn dentitions showed satisfactory results in the short term.

The Ability of Two Chewing Simulation Devices in Emulating the Clinical Deterioration of Anterior Composite Restorations in Severely Worn Teeth

PURPOSE

This study investigated the ability of two chewing simulation devices to emulate in vitro the clinical deterioration observed in anterior composite restorations in severe tooth-wear patients.

MATERIALS AND METHODS

Advanced tooth wear was simulated in bovine incisors, which were restored with palatal and buccal direct composite veneer restorations. The incisal edges of restorations were subjected to 960K cycles of either compressive loading (Biocycle-V2; 125 N at 2 Hz) or wear and mechanical loading (Rub and Roll; 30 N at 20 rpm). Surface degradation was rated using FDI scores to compare the chewing devices (Fisher's test, a = 0.05). Topography and deterioration of restorations was analyzed using SEM. The ability to emulate the deterioration was investigated by comparing the surface degradation observed in vitro with the clinical degradation observed in restorations placed in severe tooth-wear patients after 3.5 years.

RESULTS

Distinct degradation patterns were observed between the simulation devices: Biocycle-V2 generated deterioration that was not comparable to the clinical situation, including contact damage, minor wear, and localized roughening. The degradation caused by Rub and Roll was more similar to the in vivo situation, including wear facets, chipping, delamination, staining, and marginal ditching. The FDI scores were different between the chewing devices for surface/marginal staining, material/retention, and marginal adaptation (p = 0.003). SEM analysis showed microcracking at the interface between composite layers at the incisal edges.

CONCLUSIONS

The Rub and Roll chewing device was able to emulate the clinical deterioration observed in anterior restorations in severe tooth-wear patients and thus may be used as an oral-cavity simulation method, contributing to translational research.

Laboratory methods to simulate the mechanical degradation of resin composite restorations

OBJECTIVES

This study reviewed the literature to identify in vitro approaches that have been used to simulate the mechanical degradation and fatigue of resin composite restorations.

METHODS

A search for articles was carried out in 4 databases and included studies in which composite restorations were bonded to teeth and subject to cyclic loading. Articles were assessed for eligibility, and the following items were the extracted from the included studies: authors, country, year, materials tested, simulation device and details including load magnitude and frequency, number of cycles, type of antagonist, test medium, and temperature. Data were analyzed descriptively.

RESULTS

The 49 studies included showed a high level of heterogeneity in methods, devices, and test parameters. Nineteen different simulation devices were used, applying loads varying between 30 and 2900 N, and frequencies varying between 0.4 and 12 Hz. The load and frequency used most often were ~ 50 N (63.3%) and 1.5-1.7 Hz (32.7%). The number of cycles varied between 10 K and 2.4 M, 1.2 M was the most prevalent (40.8%). The majority of studies combined cyclic loading with at least one additional aging method: static liquid storage, thermo-mechanical cycling applied simultaneously, and thermal cycling as a discrete aging step were the three most frequent methods. The overall evidence indicated reporting problems, and suggested a lack of clinical validation of the research methods used.

SIGNIFICANCE

Validation studies, underlying clinical supporting data, and better reporting practices are needed for further improving research on the topic. Specific suggestions for future studies are provided.

Randomized controlled trial on the performance of direct and indirect composite restorations in patients with severe tooth wear

OBJECTIVE

The study aimed to evaluate survival and failure behavior of Direct Composite Restorations (DRC) and Indirect Composite Restorations (ICR) on molars and anterior teeth, in a Randomized Controlled Trial (RCT).

METHODS

Patients with generalized severe tooth wear were included, and randomly assigned to one of 2 protocols: (1) DCR: All teeth were restored with directly applied micro-hybrid composite restorations (Clearfil AP-X, Kuraray) for load bearing areas and nano-hybrid composite restorations (IPS Empress Direct, Ivoclar Vivadent) for buccal veneers; (2) ICR: First molars were restored with indirect composite 'tabletop' restorations and maxillary anterior teeth were restored with indirect palatal veneer restorations (Clearfil Estenia C&B, cemented with Panavia F, Kuraray). Remaining teeth were restored directly. Restorations were evaluated after 3 years, focusing on clinical acceptability. Statistical analysis was performed using Kaplan Meier curves, Annual Failure Rates (AFRs), and univariate Cox regression analyses (p < 0.05).

RESULTS

41 patients (age: 36.6 ± 6.6y) were evaluated after 3 years (40.0 ± 2.2 m). 408 restorations on first molars and palatal veneers on maxillary anterior teeth were part of this RCT, with 220 DCRs and 188 ICRs. No differences in survival between treatment modality for palatal veneers for any failure criteria were found. Tabletop restorations on first molars showed a considerable higher failure rate for ICR compared to DCR (p = 0.026, HR: 3.37, 95%CI = 1.16-9.81).

SIGNIFICANCE

In this RCT, directly applied composite restorations showed superior behavior compared to the indirect composite restorations, when used in the molar region.

Clinical performance of direct composite resin restorations in a full mouth rehabilitation for patients with severe tooth wear: 5.5-year results

OBJECTIVES

To evaluate the 5.5-year performance of direct resin composite restorations, prescribed for patients with severe tooth wear, requiring full-mouth rehabilitation.

METHODS

A convenience sample of 34 patients were recruited to a prospective trial between December 2010 and June 2013. The participants were provided 1269 full-mouth direct resin composite restorations (Clearfil AP-X) by 5 experienced operators, using the DSO-technique. Treatment resulted in an increase in the vertical dimension of occlusion (VDO). Failure was assessed at three levels. Frequencies of failure were analysed using Kaplan Meier survival curves and the effects of the relevant variables calculated with a multifactorial Cox regression (p < 0.05).

RESULTS

Annual failure rates (for all levels of failure, 'Level 3- ') of ≤ 2.2% and ≤ 2.9% were respectively reported for the anterior and posterior restorations with a mean observation time of 62.4 months. The completion of an anterior restoration with the need for further appointments resulted in significantly more Level 2- & 3- failures. An evaluation of the performance of the premolar and posterior maxillary restorations showed significantly lowered risks of certain types of failures, compared to the molar and posterior mandibular restorations.

CONCLUSIONS

At 5.5 years, 2.3% of the overall restorations displayed catastrophic, (Level 1) failures. Molar restorations, posterior mandibular restorations and the anterior restorations requiring two further sessions for completion, were associated with significantly higher risks for failure.

CLINICAL SIGNIFICANCE

Direct resin composite can offer an acceptable medium-term option for the treatment of severe, generalized tooth wear; molar restorations may require higher maintenance.

A comparative evaluation between the reliability of gypsum casts and digital greyscale intra-oral scans for the scoring of tooth wear using the Tooth Wear Evaluation System (TWES)

Background

The Tooth Wear Evaluation System (TWES) is a type of tooth wear index. To date, there is the lack of data comparing the reliability of the application of this index on gypsum cast records and digital greyscale intra‐oral scan records.

Objectives

A comparative evaluation between the use of gypsum cast records and digital greyscale intra‐oral scan records with the reliability of tooth wear scoring using the TWES amongst a group of patients with tooth wear.

Methods

Records for 10 patients with moderate to severe tooth wear (TWES ≥ 2) were randomly selected from a larger clinical trial. TWES grading of the occlusal/incisal, buccal and palatal/lingual surfaces was performed to determine the levels of intra‐ and interobserver agreement. Intra‐observer reproducibility was based on the findings of one examiner only. For the interobserver reproducibility, the findings of two examiners were considered. One set of models/ records were used per patient. Cohen's weighted kappa (κ_W) was used to ascertain agreement between and within the observers. Comparison of agreement was performed using t tests (P < .05).

Results

For the scoring of the of the total occlusal/incisal surfaces, the overall levels of intra‐ and interobserver agreement were significantly higher using the gypsum cast records than with the digital greyscale intra‐oral scan records, (P < .001) and (P < .001), respectively. For the overall buccal surfaces, only a significant difference was found in the intra‐observer agreement using gypsum casts, (P = .013). For the palatal/lingual surfaces, a significant difference was only reported in the interobserver agreement using gypsum casts, (P = .043). At the occlusal/incisal surfaces, grading performed using gypsum casts, culminated in significantly higher TWES scores than with the use of the digital greyscale intra‐oral scans (P < .001). At the buccal and palatal/lingual surfaces, significantly higher wear scores were obtained using digital greyscale intra‐oral scan records (P < .009).

Conclusions

The TWES can offer a reliable means for the scoring of wearing occlusal/incisal surfaces using gypsum casts. The reliability offered by digital greyscale intra‐oral scans for consecutive scoring was in general, inferior.

Silane Coupling Agents are Beneficial for Resin Composite Repair: A Systematic Review and Meta-Analysis of In Vitro Studies

PURPOSE

To systematically review the literature to determine whether silane combined with adhesive application improves the repair bond strength of direct methacrylate-based resin composites in comparison to the use of an adhesive alone.

MATERIALS AND METHODS

The literature up to December 2019 was searched through PubMed/MEDLINE, Scopus, and Lilacs databases with no publication year or language limits. From 676 potentially eligible studies, 81 were selected for full-text analysis, and 19 were included in the systematic review. Two reviewers independently selected the studies, extracted data, and assessed the risk of bias. Meta-analyses were conducted using a random effects model to calculate pooled mean differences between adhesive- vs silane-plus-adhesive surface treatments (global meta-analysis) and considering subgroup analyses (immediate and aged repair bond strengths and type of silane - hydrolyzed or nonhydrolyzed). Statistical analyses were performed using RevMan5.3 at a significance level of 5%.

RESULTS

Global meta-analysis showed that the use of silane prior to adhesive application produced significantly higher repair bond strengths (p=0.003). A higher mean difference (effect size: 7.30, 95% CI: 2.91-17.51) between groups was found when nonhydrolyzed silanes were used. The heterogeneity was high. Studies scored between medium and high risk of bias.

CONCLUSION

An additional silane application step could increase the repair bond strength of methacrylate-based resin composites.

A study to investigate habits with tooth wear assessments among UK and non-UK dental practitioners

Aim To assess the habits of tooth wear risk assessment and charting using a tooth wear index, by UK and non-UK dental practitioners.Design A questionnaire-based evaluation.Methods Three hundred and two completed questionnaires were returned and the outcomes analysed using descriptives, Chi-squared test and Fisher's exact test in SPSS. Significance was inferred at p <0.05.Results Based on a sample of 297 responses, 81% agreed to the need to undertake risk assessment for all dental patients attending for a first-time consultation. Fifty-nine percent undertook risk assessments for 'new patients' previously identified with signs of severe tooth wear. The routine use of a clinical index to perform tooth wear charting was described by 13.5%, with 5% documenting the frequent use of the BEWE tool. While specialist dental practitioners or those with further post-graduate training were more likely to use a tooth wear index (p <0.05), there were no other significant relationships between any of the variables in the sample and the practising habits assessed.Conclusion This investigation alludes to good levels of professional awareness of tooth wear. However, the need for improvement with the actual undertaking of risk assessments for tooth wear and consistency with tooth wear assessment and charting was determined. The need for appropriate professional guidance for the undertaking of tooth wear assessments is supported by the outcomes of this investigation.

[Cup-shaped tooth wear defects: more than erosive challenges?]

The underlying mechanism of the development of cups and grooves on occlusal tooth surfaces is still unclear. The aim of this study was to evaluate factors contributing to in-vitro cup formation, and to elucidate the clinical process. Extracted human molar teeth were exposed to acidic aqueous solutions at pH of 4.8 and 5.5 in combination with different loading conditions: no load (0N, control), 30N or 50N. Before and after 3 months exposure, the samples were scanned using a non-contact profilometer. A statistically significant difference between a loading of 0N and 50N was found at pH 4.8 (p < 0.002). Cup shaped lesions had formed only at pH of 4.8, in the 30N and 50N groups. The study showed that a cup can arise fully in enamel and that this requires simultaneous acidic and mechanical loading.

Cup-Shaped Tooth Wear Defects: More than Erosive Challenges?

BACKGROUND/AIM

The underlying mechanism of the development of cups and grooves on occlusal tooth surfaces is still unclear. The aim of this study was to evaluate factors contributing to in vitro cup formation, in order to elucidate the clinical process.

METHODS

A total of 48 extracted human molar teeth were exposed to acidic aqueous solutions at pH of 4.8 and 5.5 in constant motion, in combination with different loading conditions: no load (0N group, control), 30 N (30N group) or 50 N (50N group) (n = 8 per group). Before and after 3 months of exposure (1,422,000 loading cycles), the samples were scanned using a non-contact profilometer. Pre- and post-exposure scans were subtracted and height loss and volume tissue loss were calculated. Representative samples with wear and cupping lesions were imaged using scanning electron microscopy, light microscopy and micro-computed tomography.

RESULTS

Average height and volume tissue loss at pH 5.5 was 54 µm and 3.4 mm3 (0N), 52 µm and 3.4 mm3 (30N) and 58 µm and 3.7 mm3 (50N), respectively, with no statistically significant differences. Average height and volume loss at pH 4.8 were 135 µm and 8.7 mm3 (0N), 172 µm and 12.6 mm3 (30N) and 266 µm and 17.8 mm3 (50N), respectively, with a statistically significant difference between 0N and 50N (p < 0.002). Cup-shaped lesions had formed only at pH of 4.8, in the 30N and 50N groups.

CONCLUSION

The study showed that a cup can arise fully in enamel and that mechanical loading in addition to erosive challenges are required.

Mimicking and Measuring Occlusal Erosive Tooth Wear with the "Rub&Roll" and Non-contact Profilometry

Chewing, drinking, and occasional tooth grinding will result in physiological tooth wear during a lifetime. Extreme challenges, such as bruxism or habitual chewing on foreign objects, may lead to excessive wear. Recently, the role of erosion in accelerating mechanical tooth wear has been recognized, but the interplay between chemical and mechanical wear processes has not been extensively studied. Our laboratory recently introduced a novel oral wear simulation device, the Rub&Roll, that enables the user to perform wear and loading studies separately or simultaneously in an erosive and/or abrasive environment. This manuscript describes an application of the device: the combined mechanical and erosive loading of extracted human (pre)molars in a simulated chewing movement, with a controlled application of force, velocity, fluid, and time, and the application of non-contact profilometry in visualizing and measuring the resulting wear pattern. The occlusal morphology that was created in the experiment with the highest loading level is very similar to the clinical presentation of erosive wear.

Case Report: A Predictable Technique to Establish Occlusal Contact in Extensive Direct Composite Resin Restorations: The DSO-Technique

This paper describes the application technique of direct shaping by occlusion (DSO) for large composite restorations including the entire occlusal surface. For this technique, matrix bands and wedges are inserted without interference with antagonists in the desired occlusion. The final increment of soft-composite resin is shaped by letting the patient occlude on the uncured composite. Due to the nature of the technique, special care has to be taken for moisture control and handling of contamination. The procedure, advantages, and limitations of the technique are discussed.

Intraoral Repair of Direct and Indirect Restorations: Procedures and Guidelines

The service life of defective direct or indirect restorations could be prolonged by repair or relayering actions where durable adhesion of resin-based composite materials is established for longevity of repairs. The advances in adhesive technologies have introduced several surface conditioning concepts to adhere resin composites onto different restorative materials. The purpose of this report is to summarize reasons for failure, survival of repaired reconstructions, elaborate upon types and mechanisms of available surface conditioning methods, and present operative dentists with practical guidelines for intraoral repair procedures.

[Intra-oral restoration and correction of single- and multi-unit dental prostheses]

In cases of a fracture of the porcelain or non-aesthetic margin of a correctly functioning single- or multi-unit dental prosthesis, an intra-oral restoration or correction using a resin composite can generally be chosen. To establish adhesion to metal, porcelain, resin and composite, macro-mechanical, micromechanical and/or chemical retention methods are available. In order to achieve macro-mechanical retention, the preparation ofpits, grooves and/or undercuts is necessary. Micromechanical retention indicates surface roughening of the prosthodontic material at microscopic level through etching or sand-blasting. For chemical retention methods, special primers are used which may react chemically with the several prosthodontic materials. The treatment of choice is determined by the prosthodontic material and the feasibility of the retention method.

Influence of volumetric shrinkage and curing light intensity on proximal contact tightness of class II resin composite restorations: in vitro study

BACKGROUND

Proximal contact tightness of class II resin composite restorations is influenced by a myriad of factors. Previous studies investigated the role of matrix band type and thickness, consistency of resin composite, and technique of placement. However, the effect of volumetric shrinkage of resin and intensity of curing light has yet to be determined. Thus, the aim of this study was to identify the influence of these factors on the proximal contact tightness when restoring class II cavity preparations in vitro.

METHODS

Sixty artificial molars were restored with either a low-shrinkage (Filtek Silorane, 3M ESPE) or a conventional (Z100, 3M ESPE) composite and polymerized with low-intensity (Smartlite IQ2, Dentsply) or high-intensity light curing units (Demi(TM), Kerr). Proximal contact tightness was measured using the Tooth Pressure Meter. Data were statistically analyzed using one-way analysis of variance and Tukey post hoc test.

RESULTS

Use of low-shrinkage composite (Filtek Silorane) resulted in significantly tighter proximal contacts compared to the use of conventional composite (Z100) when cured with the same polymerization unit (p<0.001). Moreover, the low-intensity curing unit (IQ2) resulted in significantly tighter contacts than the high-intensity unit when material is constant (p<0.001).

CONCLUSIONS

Low-shrinkage resin composite and low curing light intensity is associated with tighter proximal contact values.

Surface roughness of etched composite resin in light of composite repair

OBJECTIVES

In search for clinically effective composite repair protocols, the effect of various etching protocols on the surface roughness of composite resins with different filler composition were investigated.

METHODS

Of two composite resins (hybrid-filled Clearfil AP-X; nano-filled Filtek Supreme XT) specimens of 3mm thick with a diameter of 7 mm were prepared (n=24). The top surface was polished with 4000-grit SiC-abrasive paper and subjected to one of eight surface treatments: (n=3): negative control (NC), 37% phosphoric acid for 20s (37PA-20s), 3% hydrofluoric acid for 20s (3HF-20s), for 120 s (3HF-120 s), 9.6% hydrofluoric acid for 20s (9.6HF-20s), for 120 s (9.6%HF-120 s), 37PA-20s followed by 9.6%HF for 120 s (37PA-20s/9.6HF-120 s) and 9.6%HF for 120 s followed by 37PA-20s (9.6HF-120s/37PA-20s). Roughness (S(a)) was measured using a 3D noncontact optical interferometer (WYKO) and surface topography imaged by SEM. Multilevel models were used to estimate the variances within a sample and between samples in each group. Using the resulting overall variances and the means for each group, the eight groups were compared consecutively using t-tests (p<0.05).

RESULTS

The hybrid-filled composite resin demonstrated a significantly rougher surface than the nano-filled (p<0.05). For both composites 9.6%HF-120 s, 37PA-20s/9.6HF-120 s and 9.6%HF-120 s/37PA-20s resulted in a large increase in roughness compared to the other groups (p<0.05). For the hybrid-filled, the succeeding groups (37PA-20s, 3HF-20s, 3HF-120 s and 9.6HF-20s) resulted in a statistically significant increase in surface roughness (p<0.02). For the nano-filled only a statistically significant increase in roughness was found between 3HF-20s and 3HF-120 s (p<0.001) and between 9.6HF-20s and 9.6HF-120 s (p<0.001). SEM surface characterization revealed that the hybrid-filled composite resin was much more affected by etching than the nano-filled.

SIGNIFICANCE

Composite resins should not be seen as a group of materials having identical properties when it comes to repair. The effect of etching will depend on the composition of the filler particles.

Creating Tight Proximal Contacts for MOD Resin Composite Restorations

Objective

The purpose of this study was to compare proximal contact tightness (PCT) of MOD resin composite restorations placed with different matricing protocols.

Methods

Forty-five ivorine lower right first molars with standardized MOD cavities were equally divided into three groups according to the restoration protocol. Group 1: Sectional matrix (Standard matrix, Palodent, Dentsply) secured with a wedge (Premier Dental Products Co.) and separation ring (BiTine I, Palodent, Dentsply, York, PA, USA) was used to restore the mesial surface first and then removed and repeated for the distal surface. Group 2: Identical to group 1, but separation rings were placed at both the mesial and distal sides (BiTine I+II, Palodent) prior to restoration. Mesial surface was restored followed by distal. Group 3: Walser matrix (O-form, Dr. Walser Dental GmbH) was used. Following composite resin restoration, PCT was measured using the tooth pressure meter. Data were analyzed using analysis of variance and a Tukey post hoc test (p&lt;0.05).

Results

PCT values for mesial contacts were 2.99 ± 0.47N for group 1, 4.57 ± 0.36N for group 2, and 3.03 ± 0.79N for group 3. For the distal contacts, the values were 4.46 ± 0.44N for group 1, 5.12 ± 0.13N for group 2, and 0.76 ± 0.77N for group 3. Significantly tighter contacts were obtained for mesial and distal contacts for group 2 compared to groups 1 and 3 (p&lt;0.05). For groups 1 and 3, mesial contacts were not significantly different (p=0.993), while distal contacts for group 1 were significantly tighter (p&lt;0.001).

Conclusion

Within the limitations of this study, tighter contacts can be obtained when sectional matrices and separation rings are applied to both proximal surfaces prior to placement of the resin composite in MOD cavities.

Evaluation of proximal contact tightness of Class II resin composite restorations

OBJECTIVE

The objective of the current study was to compare in-vitro the proximal contact tightness (PCT) of Class II resin composite restorations (RCR) placed with different established and new placement techniques.

METHODS

105 ivorine lower left first molars with standardized MO cavities were randomly divided into seven groups (n = 15) as follows: SRing: sectional matrix and separation ring (Garrison Dental); CRing: circumferential matrix (1101-c, KerrHawe SA) with separation ring; CWedge: circumferential matrix with a wedge only; COptra: circumferential matrix and OptraContact (Vivadent); CCerana: circumferential matrix and a Cerana insert (Nordiska Dental); CElliot: circumferential matrix and Elliot separator (PFINGST & Co) and Walser: Walser matrix O-type (Dr Walser Dental GmbH). In all the groups, the matrix band was secured using a wooden wedge except for the Walser group, following manufacturer's recommendations. A Tofflemire retainer (Kerr Corporation) was used to apply the circumferential matrix band whenever it was used. All the prepared teeth were restored with resin composite (Premise, Kerr) mounted in a manikin head to simulate the clinical environment. PCT was measured using the Tooth Pressure Meter (University of Technology, Delft). The data were analyzed using one-way ANOVA and Tukey post-hoc tests (p < 0.05).

RESULTS

Compared to the control group (SRing) (6.64 +/- 1.06N), all other systems resulted in significantly lower PCT values (p < 0.001). Within the circumferential matrix groups, CRing (4.01 +/- 0.53N) and CElliot (4.29 +/- 1.08N) showed significantly tighter contacts compared to the CWedge (0.37 +/- 0.22N), COptra (0.91 +/- 0.49N), CCerana (2.99 +/- 1.98N) and Walser (1.34 +/- 0.55N) (p < 0.05) group. Between CWedge and COptra, no significant difference was found (p = 0.57).

CONCLUSION

The use of separation rings with sectional matrices provides superior contacts when placing Class II RCRs.

Longevity and reasons for failure of sandwich and total-etch posterior composite resin restorations

PURPOSE

To investigate longevity and reasons for failure of Class II posterior composite restorations (PCRs) placed with or without a lining of glass-ionomer cement.

MATERIALS AND METHODS

Four hundred fifty-eight Class II PCR placed in 248 patients (110 male, 138 female, age 18 to 80) by two dentists in a general practice between 1988 and 1997 were retrospectively examined from the patient files. The restorations were placed either with a total-etch technique or with a resin-modified glass-ionomer lining placed on the dentin. Items recorded were date of placement, date of last check-up visit, tooth number, and restored surfaces. Date of replacement and reason for failure of the PCR was recorded. A restoration was clinically acceptable when still in function and acceptable at the last check-up visit. Additionally, the caries risk for each patient was estimated by the treating clinician. Life tables and Kaplan-Meier curves were used to express survival rates. A Cox regression was applied to assess the influence of variables on survival.

RESULTS

Three hundred seventy-six total-etch PCRs and 82 PCRs with a lining were investigated. After 9 years, survival percentages of 88.1% for total-etch restorations and 70.5% for restorations with a resin-modified glass-ionomer lining were found. The most important reasons for failure were fracture and caries. Predominantly, failures started occurring after 3 to 4 years of clinical service. Results of the Cox regression show that the presence of a lining and high risk for caries significantly increased the failure rate of the restorations.

CONCLUSION

PCRs placed with a resin-modified glass-ionomer lining clinically showed more frequent fractures than PCRs placed with a total-etch technique.

Comparison of proximal contacts of Class II resin composite restorations in vitro

This study investigated the tightness of the proximal contact when placing posterior resin composite restorations with circumferential and sectional matrix systems in an in vitro model using a special measuring device (Tooth Pressure Meter). A manikin model was used with an artificial first molar in which an MO-preparation was ground, simulating the clinical situation of an amalgam replacement. This preparation was duplicated, resulting in 160 identically prepared teeth. These teeth were divided into 8 groups (n=20). In 2 groups, circumferential matrix bands (flat or contoured) in a Tofflemire retainer were applied. In the remaining 6 groups, 3 different separation rings were combined with 2 types of sectional matrix bands. All the cavities were restored using Clearfil Photo Bond and Clearfil AP-X. The tightness of the proximal contact was measured using the Tooth Pressure Meter. Data were statistically analyzed using SPSS 12. ANOVA was used to find differences in proximal contact tightness between the groups. Tukey tests were used to find differences between the homogeneous subgroups. The use of sectional matrices combined with separation rings resulted in tighter proximal contacts compared to when circumferential systems were used (p<0.001). The use of these devices is therefore recommended when posterior resin composite restorations are placed.

A retrospective clinical study on longevity of posterior composite and amalgam restorations

OBJECTIVES

The purpose of this study was to evaluate retrospectively the longevity of class I and II amalgam and composite resin restorations placed in a general practice.

METHODS

Patient records of a general practice were used for collecting the data for this study. From the files longevity and reasons for failure of 2867 class I and II amalgam and composite resin restorations placed in 621 patients by two operators between 1990 and 1997 were recorded in 2002.

RESULTS

912 amalgam restorations (502 by operator 1 and 410 by operator 2) and 1955 posterior composite resin restorations (1470 by operator 1 and 485 by operator 2) were placed. One hundred and eighty-two amalgam and 259 posterior composite resin restorations failed during the observation period. The main reasons for failure of the restorations were caries (34%), endodontic treatment (12%) and fracture of the tooth (13%). Life tables calculated from the data reveal a survival for composite resin of 91.7% at 5 years and 82.2% at 10 years. For amalgam the survival is 89.6% at 5 years and 79.2% at 10 years. Cox-regression analysis resulted in a significant effect of the amount of restored surfaces on the survival of the restorations. No significant effect of operator, material as well as combination of material and operator was found.

SIGNIFICANCE

In the investigated general practice, two dentists obtained comparable longevity for amalgam and composite resin restorations.

Influence of composite resin consistency and placement technique on proximal contact tightness of Class II restorations

PURPOSE

To investigate the influence of composite resin consistency and placement technique on proximal contact tightness of Class II composite resin restorations.

MATERIALS AND METHODS

A manikin model (KaVo Dental) was used with an artificial first molar in which a standardized MO preparation was ground. This preparation was duplicated 360 times. Cavities were restored using Clearfil Photo Bond (Kuraray) combined with one of three composite resins of different consistencies: a low-viscosity (X-Flow, Dentsply), a medium-viscosity (Clearfil AP-X, Kuraray) and a high-viscosity composite (Tetric Ceram HB, Ivoclar Vivadent). Each composite was combined with 6 different matrix systems and separation techniques (n = 20). Groups 1 and 2: precontoured metal circumferential matrix (KerrHawe 1101-c) in a Tofflemire retainer combined either with hand instrument (OptraContact, Ivoclar Vivadent) or separation ring (Composi-Tight Gold, Garrison Dental Solutions). Group 3: pre-contoured metal sectional matrix (Lite-Flex, Danville Materials) with separation ring. Groups 4 and 5: pre-contoured metal circumferential dead-soft matrix (Adapt SuperCap, KerrHawe) with or without separation ring. Group 6: flat metal circumferential matrix (OptraMatrix, Ivoclar Vivadent) in a Tofflemire-retainer with hand instrument (OptraContact). Proximal contact tightness was measured using the Tooth Pressure Meter (University of Technology, Delft). To determine the effect of experimental variables on the proximal contact tightness, a multiple linear regression model was constructed.

RESULTS

Measurements in group 6 were not possible; therefore, this group was excluded. The use of medium- or high-viscosity instead of a low-viscosity composite resin resulted in statistically significantly tighter proximal contacts (p < 0.01). The use of a separation ring resulted in a large, statistically significant increase (p < 0.001) in contact tightness, while the use of a hand instrument resulted in a small, statistically significant increase of contact tightness (p = 0.017). No statistically significant differences were found when a dead-soft matrix or a sectional matrix was used instead of a Tofflemire (p = 0.159, p = 0.261, resp.).

CONCLUSION

Use of a separation ring when restoring a Class II composite resin restoration has a greater influence on the obtained proximal contact tightness compared to the influence of the consistency of the composite resin.

The long-term effect of a composite resin restoration on proximal contact tightness

OBJECTIVE

The aim of this study was to investigate changes in proximal contact tightness up to 6 months after the restorative treatment.

MATERIALS AND METHODS

In a randomised clinical trial Class II composite resin restorations were placed in 52 patients. Proximal contact tightness was measured before, directly after, and 6 months after treatment. These data were analysed statistically using linear regression and t-tests.

RESULTS

Proximal contacts, that increased in tightness as result of the treatment tend to loose tightness after a 6-months period but remain tighter than before treatment. Proximal contacts, that decreased after treatment hardly change after 6 months.

CONCLUSIONS

A change in contact tightness after restorative treatment will not always remain stable over time.

A randomized clinical trial on proximal contacts of posterior composites

OBJECTIVE

The objective of this study was to investigate clinical changes in proximal contact strength inserting Class II composite resin restorations according to one of three randomly assigned protocols.

MATERIALS AND METHODS

Seventy-one Class II restorations (MO/DO) were placed by two calibrated operators. Restorations were randomly assigned to one of three groups: one using a circumferential and two a sectional matrix system with separation rings. Proximal contacts were measured by one independent observer with a Tooth Pressure Meter immediately before treatment, and directly after finishing the restoration.

RESULTS

Compared to the situation before treatment groups with a sectional matrix system resulted in a statistical significant stronger mean proximal contact strengths (p<0.05), whereas the use of a circumferential matrix system with hand-instrument resulted in a lower proximal contact strength (p<0.05).

CONCLUSION

Class II posterior composite resin restorations placed with a combination of sectional matrices and separation rings resulted in a stronger proximal contact than when a circumferential matrix system was used.

Five-year clinical performance of posterior resin composite restorations placed by dental students

OBJECTIVES

To investigate the survival over a five-year period of posterior resin composite restorations placed by students.

METHODS

Class I and II resin composite restorations placed by second-fourth year dental students were evaluated. Patients attended the dental school every 6 months for a regular check-up during which all restorations were checked on their clinical acceptability. In case of replacement or repair of a restoration, this was registered in the patient's record. From each record the survival time and reasons for failure of resin composite restorations were gathered.

RESULTS

Seven-hundred three posterior resin composite restorations in 382 patients (49% female and 51% male, age 22-78) were evaluated. At 5 years 560 of the 703 restorations were still considered to be "clinically acceptable". Forty-nine restorations were considered as "functionally present", of which 44 were restored with a crown and four had received a new restoration adjacent to the existing restoration without its removal. Ninety-four restorations had failed. The main reasons for failure were restoration fracture, caries, endodontic treatment, defective margin and lack of proximal contact. The survival rate of the restorations was 87% at 5 years, resulting in an annual failure rate of 2.8%.

CONCLUSIONS

Dental students are able to place resin composite restorations in posterior teeth with an acceptable mean annual failure rate.

The amalgam-free dental school

OBJECTIVES

To review the change in teaching of Restorative Dentistry at Nijmegen dental school over the period 1986 to the present.

KEY POINTS

In 1986, class I and II resin composite restorations were included in the pre-clinical program. However, these courses still started with class I and II amalgam restorations. From 1990 on, the number of amalgam restorations placed in the clinic gradually decreased while the number of resin composite restorations increased. Meanwhile, resin composite had become the first choice for treatment of primary caries (class I and class II) lesions. Finally in 1994, the pre-clinical training started with resin composite restorations before dental amalgam was taught and the advantage of a minimal preparation was further emphasized. Since 2001 the teaching of dental amalgam ceased at the dental school. This was not an abrupt change but the result of a long transitional stage during which it was gradually substituted by resin composite. This step-by-step introduction allowed the acceptance of composite resin by the staff as an alternative for dental amalgam in posterior restorations. As in 2001 students placed only 2.5 amalgam restorations before graduation, it was decided to stop with the pre-clinical training program.

CONCLUSIONS

The introduction of resin composites meant an important change in teaching restorative dentistry at Nijmegen dental school. It was not just a change in materials and techniques but also a change in treatment philosophy. The reduced need for preparation and the strengthening effect on the remaining tooth were the principal reasons for the shift from dental amalgam to adhesive dentistry with resin composite at Nijmegen dental school.