Analytical strategies for clinical studies on dental erosive wear.

BACKGROUND: There is a need for analytical techniques for measuring Erosive Tooth Wear (ETW) on natural surfaces in clinical studies. The purpose was to investigate the use of two instruments aimed to assess initial to more advanced stages of ETW. METHODS: Human premolar enamel samples (2x3mm) (n = 24), were polished flat and mounted in resin cylinders (4 cylinders, 6 samples in each). Part 1: Baseline analyses by White Light Interferometer (WLI), Surface Reflection Intensity (SRI: TableTop and OptiPen) and Surface Hardness (SH). Erosion (1% citric acid (pH 3.6) for 1, 2, 4, 6, 8, 10 min. SRI and SH analyses after every erosion episode and by WLI after 10 min. New indentations were made and enamel loss; was measured by change in indentation depths from toothbrush abrasion (200 g, 60 strokes, 30 s). Another series of 2 × 5 min erosion (totally15 min and 20 min) was analysed with SH and SRI after each erosion, and by WLI (on samples and impressions of samples) after 20 min. Part 2 investigated WLI performance in the interface where initial erosion increases in severity and substance loss occurs. The samples were repolished. Baseline analyses by WLI, SRI (TableTop and OptiPen) and SH. Four cylinders were etched for 1, 2, 4, 8 min respectively and analysed by SRI, SH on samples, and WLI on samples and impressions). RESULTS: Part1: SRI decreased from baseline to ~ 6 min etch and increased slightly after abrasion, the two devices correlated well (ICC 0.98 p < 0.001, Spearmans rs 0.91 p < 0.001). SH decreased nearly linearly to 10 min etch, but increased distinctly after abrasion. Mean enamel loss from abrasion alone was 0.2 µm (change in indentation depths). After 10 min etch, it was 0.27 µm (WLI) and after 20 min etch, it was 2.2 µm measured on samples vs 2.4 µm on impressions of samples (7% higher). Part 2: From baseline to 8 min etch; SRI and SH decreased whereas WLI presented increasing etch depths. CONCLUSIONS: With some adjustments, the use of SRI and WLI in combination seems to be a promising strategy for monitoring ETW in clinical studies.

How serious is Molar Incisor Hypomineralisation (MIH) among 8- and 9-year-old children in Bosnia-Herzegovina? A clinical study.

AIM: To determine the prevalence of MIH in 8- and 9 year-old children in the city of Kljuc, Bosnia-Herzegovina, and to describe the distribution and severity of the affected teeth. MATERIALS AND METHODS: Study design: All 8- and 9-year-olds (n=104) living in Kljuc (born 2004/2005) were invited to participate, and 103 were examined by a calibrated clinician. Written, informed consent was obtained from all participants' relatives, as well as a questionnaire designed to assess potential risk indicators. Index teeth were all permanent first molars and incisors (12 teeth). Opacities (>1mm), post eruptive breakdown (PEB), atypical restorations and previous extractions caused by MIH were registered. RESULTS: The prevalence of MIH was 11.7% (n=12), significantly higher for girls than for boys (14.6% vs. 9.7%; p<0.05). The maxillary first molars and incisors were 1.8 (p<0.02) and 2.3 (p<0.05) times more frequently affected than the mandibular ones, respectively. Seven (30%) of the affected molars had opacities, 8 (35%) had PEB and 8 (35%) atypical restorations. No molars had been extracted due to MIH. The use of penicillin due to adenoid infections in the first 5 years was associated with a higher prevalence of MIH (41.7% vs. 19.6%). CONCLUSIONS: The prevalence of MIH (11.7%) supports the data previously published from Bosnia-Herzegovina. Girls had higher prevalence of MIH than boys; first molars and incisors in the maxilla were almost twice as often affected as in the mandible. Use of penicillin in the first 5 years was associated with a higher prevalence.

The Susceptibility to Dental Erosion Differs among Individuals.

Studies of wine tasters and patients with self-induced vomiting have revealed that 30-50% of individuals at high risk do not develop erosive lesions. The aim was to investigate this apparent individual susceptibility to enamel erosion. Two enamel specimens were made from each of 3 premolars from 8 persons (donors). Six acrylic mouth appliances were worn by 6 volunteers (carriers). One specimen from each donor was mounted on each appliance. The carriers wore the appliances for 9 days. The appliances were immersed in 0.01 M HCl for 3 min twice per day to imitate a vomiting/reflux situation. The enamel specimens were analysed by a white-light interferometer to measure enamel loss (in micrometres). The enamel loss varied significantly both between the donor teeth (p = 0.009) and the carriers (p = 0.004). The lesion in the specimen with the largest amount of enamel loss was 4 times as deep as in the specimen with the lowest. In 1 carrier, all specimens displayed enamel loss above the mean, including the specimen from the donor with the most resistant enamel. The variation in susceptibility to erosion among individuals appears to be influenced both by the sustainability of the enamel and by factors in the oral environment. This could explain the variation in prevalence and severity of dental erosions among patients exposed to similar acidic challenges. The results suggest that for certain individuals, only minimal acidic challenges may be sufficient to cause damage to the teeth, while others may never develop dental erosions despite extensive exposure to acid.

Dental erosion: Prevalence and severity among 16-year-old adolescents in Troms, Norway.

AIM: To study the prevalence, distribution and severity of dental erosion among 16-year-old adolescents in the Troms region of Norway. MATERIALS AND METHODS: Study design: The participants were recruited through the Tromsø-study ("Fit Futures"), and 392 16-year-olds were examined for dental erosion using clinical intraoral photographs. Three calibrated clinicians used the Visual Erosion Dental Examination (VEDE) system to register and grade the dental erosive wear. RESULTS: More than one third (38%) of the participants showed dental erosion on at least one tooth surface, 18% were limited to the enamel, while 20% of the adolescents showed erosive wear extending into the dentine. The occlusal surfaces of the lower first molars, and the palatal surfaces of the maxillary incisors were the most often and most severely affected. Of the participants showing dental erosion, 93% exhibited "cuppings" on the molars, with 48% limited to the enamel and 52% extending into the dentine. The highest prevalence of "cuppings" (73%) was found on the first lower molars, especially the mesiobuccal cusp of the teeth. The prevalence and severity of dental erosion was found to be higher in male than in female participants (p < 0.0001). CONCLUSION: The results from this study indicate a high prevalence and severity of dental erosion among adolescents in Troms and stress the importance of information, early and effective diagnostics and implementation of prevention strategies.

Enamel formation genes associated with dental erosive wear.

Dental erosive wear is a multifactorial condition that is greatly affected by environmental factors. So far, no study has investigated how dental erosive wear is influenced by variations in enamel formation genes. The aim of the present study was to investigate polymorphisms in genes involved in enamel formation and their influence on enamel susceptibility to dental erosion. DNA samples were collected from 795 Norwegian adolescents aged 16-18 years. Five single-nucleotide polymorphism markers were genotyped in selected candidate genes (ameloblastin, amelogenin, enamelin, tuftelin 1 and tuftelin interacting protein 11), reported to influence enamel formation. Allele and genotype frequencies were compared within two patient groups with dental erosions; all participants with dental erosion and only those with severe dental erosion (erosion extending into dentine). Overrepresentation of the G allele of the enamelin marker was seen in the erosion group compared to the unaffected group (p = 0.047). When erosion severity was considered, statistical significant difference in allele frequency was observed for amelogenin, with the C allele suggesting a protective role (p = 0.02). A suggestive overrepresentation of the TT genotype of the amelogenin marker was also seen in cases with severe erosion (p = 0.049) when compared to cases with no dentine erosion. Amelogenin was also associated with severe erosion in the recessive model; the TT genotype was significantly more frequent in the affected group than in the unaffected group (p = 0.01). The present study suggests that polymorphisms in enamel formation genes are statistically associated with an individual's susceptibility to dental erosive wear.

Consensus report of the European Federation of Conservative Dentistry: erosive tooth wear--diagnosis and management.

OBJECTIVE: Due to an increased focus on erosive tooth wear (ETW), the European Federation of Conservative Dentistry (EFCD) considered ETW as a relevant topic for generating this consensus report. MATERIALS AND METHODS: This report is based on a compilation of the scientific literature, an expert conference, and the approval by the General Assembly of EFCD. RESULTS: ETW is a chemical-mechanical process resulting in a cumulative loss of hard dental tissue not caused by bacteria, and it is characterized by loss of the natural surface morphology and contour of the teeth. A suitable index for classification of ETW is the basic erosive wear examination (BEWE). Regarding the etiology, patient-related factors include the pre-disposition to erosion, reflux, vomiting, drinking and eating habits, as well as medications and dietary supplements. Nutritional factors relate to the composition of foods and beverages, e.g., with low pH and high buffer capacity (major risk factors), and calcium concentration (major protective factor). Occupational factors are exposition of workers to acidic liquids or vapors. Preventive management of ETW aims at reducing or stopping the progression of the lesions. Restorative management aims at reducing symptoms of pain and dentine hypersensitivity, or to restore esthetic and function, but it should only be used in conjunction with preventive strategies. CONCLUSIONS: Effective management of ETW includes screening for early signs of ETW and evaluating all etiological factors. CLINICAL RELEVANCE: ETW is a clinical condition, which calls for the increased attention of the dental community and is a challenge for the cooperation with other medical specialities.

The effect of daily fluoride mouth rinsing on enamel erosive/abrasive wear in situ.

It is not known whether application of fluoride agents on enamel results in lasting resistance to erosive/abrasive wear. We investigated if one daily mouth rinse with sodium fluoride (NaF), stannous fluoride (SnF(2)) or titanium tetrafluoride (TiF(4)) solutions protected enamel against erosive/abrasive wear in situ (a paired, randomised and blind study). Sixteen molars were cut into 4 specimens, each with one amalgam filling (measurement reference surface). Two teeth (2 × 4 specimens) were mounted bilaterally (buccal aspects) on acrylic mandibular appliances and worn for 9 days by 8 volunteers. Every morning, the specimens were brushed manually with water (30 s) extra-orally. Then fluoride solutions (0.4% SnF(2) pH 2.5; 0.15% TiF(4) pH 2.1; 0.2% NaF pH 6.5, all 0.05 M F) were applied (2 min). Three of the specimens from each tooth got different treatment, and the fourth served as control. At midday, the specimens were etched for 2 min in 300 ml fresh 0.01 M hydrochloric acid and rinsed in tap water. This etch procedure was repeated in the afternoon. Topographic measurements were performed by a white-light interferometer. Mean surface loss (±SD) for 16 teeth after 9 days was: SnF(2) 1.8 ± 1.9 µm, TiF(4) 3.1 ± 4.8 µm, NaF 26.3 ± 4.7 µm, control 32.3 ± 4.4 µm. Daily rinse with SnF(2), TiF(4) and NaF resulted in 94, 90 and 18% reduction in enamel erosive/abrasive wear, respectively, compared with control (p < 0.05). The superior protective effect of daily rinse with either stannous or titanium tetrafluoride solutions on erosive/abrasive enamel wear is promising.

Changes in the treatment concept for approximal caries from 1983 to 2009 in Norway.

The aim was to measure variations in threshold for operative treatment of approximal caries in permanent teeth and the use of restorative materials, compared with results from studies conducted in Norway in 1983 and 1995. In 2009, a precoded questionnaire was sent electronically to 3,654 dentists with E-mail addresses in the member register of the Norwegian Dental Association. The questions were related to caries, treatment strategies and choice of dental materials. Replies were obtained from 61% of the dentists after two reminders. Restorative treatment of approximal lesions confined to enamel, based on radiographic appearance, was proposed by 7% of the dentists, compared with 66% in 1983 and 18% in 1995. Younger dentists, significantly more often than older, would defer operative treatment of approximal lesions until the lesion was visible in dentine. While tunnel preparation most often was the preparation of choice in 1995 (47%), saucer-shaped preparation was most favoured in 2009 (69%). Tunnel preparation was only preferred by 4% of the dentists. Resin composite was the restorative material preferred by 95%, compared with 16% in 1995. The corresponding values for conventional glass ionomer cement (GIC) were 1 versus 22%, for resin-modified GIC 1 versus 7%, and for a combination of GIC and resin composite 2 versus 22%. Compomer was preferred by 1% of the respondents. The authors conclude that treatment concepts for approximal caries have changed considerably during the last 26 years. In 2009, only 7% of dentists reported that they would treat approximal caries operatively before the lesion reached dentine.

Protective effect of TiF(4) solutions with different concentrations and pH on development of erosion-like lesions.

AIM: To evaluate how concentration and pH of TiF(4) influence the erosion-protective effect. METHODS: Specimens were treated with a TiF(4) solution: (1) 0.5 M F, pH 1.2, (2) 0.05 M F, pH 2.1, (3) 0.5 M F, pH 2.1, or (4) 0.05 M F, pH 1.2; then, they were exposed to HCl. RESULTS: After 2 min, the proportions of the area covered with the coating were 93, 71, 17 and 0% in groups 1-4. When present, the coating seemed to protect the surface. After 6 min, a coating could only be seen in group 1 (43%). CONCLUSION: Reducing the concentration of TiF(4) and increasing the pH of the solution decreased the protective effect.

Comparing different methods to assess erosive lesion depths and progression in vitro.

The aim of this study was to compare the precision and accuracy of 5 different methods applied to assess surface substance loss or changes in surface microhardness (SMH) on the same enamel surfaces after repeated acid exposures. Ground specimens from human molars were exposed to 0.01 M HCl (pH 2.2) for 6 min × 2 and measurements performed 3 times to estimate precision. The accuracies (systematic errors) were calculated against the manufacturer's calibration standard. Lesion depth progression was from 94 to 110%, related to repeated acid exposure. The precisions/accuracies were: WLI (white light interferometry), 0.5/0.4%; SP (stylus profilometry), 4.7/0.7%; OP (optical profilometry), 1.4/12%; AAS (atomic absorption spectroscopy), 0.4/17% (measured calcium loss was converted to lesion depth). The correlation between WLI and SP was R² = 0.98, and between WLI and OP it was R² = 0.85. SMH gave information on qualitative changes of the surface (precision: 5.5%, accuracy: 4.0%). WLI performed best in precision and accuracy, but SP, OP and AAS are all relevant methods for analysing lesion depths and progression, SMH seems suitable for analysing minor changes in surface enamel only.

Reliability of two clinical scoring systems for dental erosive wear.

The aim of the study was to evaluate and compare two dental erosive wear scoring systems, the Visual Erosion Dental Examination (VEDE) and Basic Erosive Wear Examination (BEWE). Seventy-four tooth surfaces (photographs) and 562 surfaces (in participants) were scored by 5 (photographs) or 3 (in participants) clinicians using both scoring systems. The surfaces in the photographs were scored twice. The level of agreement was measured by weighted kappa (kappa(w)). Inter- and intraexaminer agreement showed small variations between the examiners for both systems when scoring the photographs. Slightly higher mean kappa(w) values were found for VEDE (kappa(w) = 0.77) compared with BEWE (kappa(w) = 0.69). When scoring the surfaces in the clinical examination the mean kappa(w) values for the two systems were equal (kappa(w) = 0.73). Interexaminer agreement using VEDE was calculated to see how differentiation between enamel and dentine lesions influenced the variability. The highest agreement was found for score 0 (sound, 86%) and score 3 (exposure of dentine, 67%), while the smallest agreement was shown for score 1 (initial loss of enamel, 30%) and score 2 (pronounced loss of enamel, 57%). The reliability of the two scoring systems proved acceptable for scoring the severity of dental erosive wear and for recording such lesions in prevalence studies. The greatest difficulties were found when scoring enamel lesions, especially initial lesions, while good agreement was observed when examining sound surfaces (score 0) and dentine lesions (score 3).

The protective effect of TiF4, SnF2 and NaF against erosion-like lesions in situ.

The aim of this in situ study was to compare the protective effect of TiF4, SnF2 and NaF on the development of erosion-like lesions in human enamel. Fourteen human molars were each divided into 4 specimens, mounted on acrylic mouth appliances and worn by 7 volunteers for 9 days. In order to mimic a feasible treatment procedure for patients with voluntary or involuntary gastric reflux, the specimens were etched for 2 min twice a day (0.01 M HCl) and fluoride applications were performed every third day (2 min). The controls were treated as the other specimens except for the fluoride applications. Etch depths and surface roughness changes (R(q)) were measured by white light interferometry. Compared with the control, TiF4 and SnF2 reduced the etching depth by 100% (p < 0.001) and 91% (p < 0.001), respectively, and both treatments resulted in an observable surface layer. NaF had no significant protective effect (p = 0.46). It can be concluded that although SnF2 provided significant protection for the enamel surfaces, TiF4 showed the best protection against acid attack, while NaF had no significant protective effect in this study.

Repair of defective composite restorations. A questionnaire study among dentists in the Public Dental Service in Norway.

OBJECTIVES: This study aimed to investigate dentists' treatment choices concerning "repair or replacement" of defective restorations. METHODS: A pre-coded questionnaire was sent electronically to all dentists (n=1313) in the Public Dental Service (PDS) in Norway. Part one: The dentists were asked about age and gender, whether they performed direct restorative therapy/amount of time spent on fillings made per day due to: Primary caries, Repair of restorations or Replacement of restoration/what kind of bonding agents used and pre-treatment of the residual restoration. Part two: The dentists were asked to consider the best treatment for three patient cases with tooth/restoration fractures. RESULTS: Response rate was 55.8%, (69.6% females, 30.4% males). Respondent age varied from 25 to 77 years (mean 41.8, SD 12.4). Part one: The dentists spent on average 57.5% of the working day placing restorations, making from 1 to 30 (mean 7.7, SD 3.6) restorations per day. Reasons for treatment were; Primary caries 55.7% (SD 19.1%), repair of restorations 26.7% (SD 14.8%), replacement of fillings 18.2% (SD 11.2%). Two-step etch and rinse (ER), 3-step ER and Self-etch (SE) were used by 48.7%, 24.6% and 26.7% of the respondents, respectively. A silanising agent was used by 7.4%. Part two: Treatment choices: Repair with RC: 89.6% in case one, 86.9% in case two and 54.1% in case three. Young dentists suggested invasive treatment more often than old dentists (>38 years). CONCLUSIONS: Operative dentistry claims 57.5% of PDS dentists' working day. In addition to primary caries, repair and replacement of restorations accounted for 27% and 18% of the reasons for placing restorations. CLINICAL SIGNIFICANCE: The idea of "minimal intervention dentistry" seems to have great influence among dentists in PDS (Norway), as they seek to preserve dental hard tissue as much as possible by choosing repair before replacement. No gender differences were observed, but older dentists seem to favour repair compared with the younger dentists.

Canines are affected in 16-year-olds with molar-incisor hypomineralisation (MIH): an epidemiological study based on the Tromsø study: "Fit Futures".

AIM: This was to determine the prevalence, distribution of affected teeth and severity of MIH in adolescents from Northern Norway. METHODS: It was part of a cross-sectional health survey Fit Futures including 16-year-olds from two neighbouring municipalities, Tromsø and Balsfjord. RESULTS: The prevalence of MIH was 13.9% (110 of 794). The maxillary first permanent molars (FPMs) were 1.6 times more frequently affected than in the mandible (P < 0.001). The FPMs on the right side were 1.2 times more often affected than the FPMs on the left side (P = 0.038). The maxillary incisors were 2.5 times more often affected than the incisors in the mandible (P < 0.001). The proportions of participants whose canines and incisors were involved were 22.8 and 41.8%, respectively. Altogether 201 FPMs were affected; 54.0% of these had opacities only, 24.3% had posteruptive breakdown (PEB), 18.8% had atypical restorations, and 3.0% had been extracted due to MIH. The buccal surfaces were most often affected in FPMs. More severe lesions were found in the mandibular FPMs compared with the maxillary FPMs (P = 0.002). In the lower canines, only opacities were recorded, while in the upper jaw 13.0% of the affected canines showed PEBs. The distribution of MIH in the dentition was not symmetrical. CONCLUSION: The prevalence of MIH (13.9%) in the study population of 16-year-olds from Northern Norway is consistent with previous Scandinavian reports. The distribution pattern shows that one participant in four with MIH had at least one affected canine. Further studies are needed to describe the localisation of defects on the enamel surface and to relate these findings to enamel thickness and the duration of amelogenesis.

Radiopacity of restorations and detection of secondary caries.

The aim of this study was to compare the accuracy of radiographic diagnosis of secondary carious lesions adjacent to filling materials with different radiopacities. Class II preparations were made in extracted teeth. One group of teeth (n = 49) had caries in the gingival wall, simulating secondary caries. The control teeth (n = 29) had no caries. Three posterior composite materials (P-30 and two experimental composites) with different radiopacities and amalgam were successively inserted into each cavity. After being radiographed, the "restorations" were removed and a new material inserted. The radiographs were interpreted by 11 dentists, and secondary caries was diagnosed according to a five-point confidence rating. The results obtained with the receiver operating characteristics (ROC) method showed that a semi-radiopaque restoration seemed favorable and that the best radiopacity slightly exceeded that of enamel.

Radiographic caries diagnosis by clinicians in Norway and Western Australia.

In connection with continuing education courses in Norway and Western Australia (WA), dealing with caries diagnosis and treatment decisions, pre-tests were conducted. The pre-tests involved 433 dentists in Norway (ND), and 62 dentists (WAD) and 108 dental therapists (WAT) in WA, altogether 603 clinicians. Radiographs of 68 approximal surfaces were to be diagnosed and a treatment proposal was requested for each surface. ND showed the best overall diagnostic quality measured by the area beneath ROC-curve (P < 0.00001). The frequency of false-positive diagnoses (over-registrations) on sound surfaces varied between 7.1% (ND) and 11.9% (WAT) while the frequency of true-positive scores for lesions in the outer half of dentine varied from 57.4% (ND) to 48.1% (WAT). The mean numbers of restorations suggested by the three groups of clinicians were: ND: 14.3; WAD: 13.0; and WAT: 14.5. None of the differences was statistically significant. The proportion of sound surfaces proposed filled varied considerably between the groups, from 4.3% among Norwegian dentists to 10.6% among WAT (P < 0.0001). Of the lesions penetrating the outer half of dentine, the ND group would have restored 34.5% and the Australian clinicians somewhat fewer: WAD 25.6% and WAT 26.5%. The 11.3% of the ND who proposed more than two fillings on sound surfaces were responsible for 51.2% of the total number of filling proposals on sound surfaces. The corresponding numbers in the Australian group were 19.4% (WAD) and 33.3% (WAT) who made 73.6% and 75.7% of the restorative proposals on sound surfaces respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiographic interpretation and treatment decisions among dental therapists and dentists in Western Australia.

All dentists and dental therapists employed in the Community Dental Services in Western Australia were invited to participate in a questionnaire study to find out about their use of radiographs and opinions and knowledge about the diagnosis of approximal caries. Replies were received from 45 dentists (95.1%) and 207 dental therapists (84.0%). Most dentists would not restore a lesion before it appeared on radiograph to have reached the dentine, while therapists were more likely to consider a restoration for a lesion just in enamel. Sixty percent of all respondents thought that a cavity was present when the radiographic lesion was confined to enamel. Fifty-seven percent of dentists thought that an average lesion took at least 12 months to progress from outer enamel to dentine, while a majority of dental therapists thought this would take less than 12 months. Radiographs were not frequently taken by the participants. Operators' opinions about cavity formation were the most important predictor of choice of treatment. In general, these participant's responses were similar to those provided by Norwegian and Dutch respondents in similar surveys conducted 5-6 yr ago, but the present participants worked in an optimally fluoridated area and might therefore have been expected to have adopted more cautious criteria for restorative treatment. Differences between dentists and dental therapists were generally not great. The results suggest that calibration of the operators in the service would offer benefits.

Vertical angulation of the X-ray beam and radiographic diagnosis of secondary caries.

The purpose of this study was to assess to what extent angulation of an X-ray beam could affect the quality of diagnoses of caries adjacent to restorations with different radiopacities. Amalgam and composite class II restorations with and without secondary caries were done in extracted teeth. The teeth were radiographed using four different vertical angulations -0, 5, 10, and 15 degrees. Eight dentists diagnosed caries lesions on these radiographs. The best diagnostic outcome was found for the composite restorations radiographed at 10 degrees vertical angulation. Diagnosis was generally better for lesions marginal to composites compared to amalgams. The quality of secondary caries diagnosis in connection with amalgam was not significantly affected by variations in vertical angulation from 0 up to 15 degrees.

Clinical behaviour of glass ionomer restorations in primary teeth.

OBJECTIVE: To compare a silver-reinforced glass ionomer material (cermet) with a resin-modified glass ionomer in minimal Class II preparations in primary teeth. METHODS: Matched pairs of primary molars with approximal caries that required operative treatment were used. Each cavity was filled with either Vitremer or Ketac-Silver. The restorations were followed for at least 36 months and examined annually using bitewing radiographs and clinical inspections. Impressions were taken at each recall and models were examined microscopically. RESULTS: After 36 months, one of the resin-modified glass ionomer (RMGI) restorations and 13 (26.5%) of the silver cermet restorations had failed. The RMGI failed because of secondary caries, while most of the failures of the silver cermet fillings were marginal defects alone or in combination with secondary caries. The median survival time (MST) for the silver cermet restorations was 37 months. The RMGI restorations had a MST exceeding 42 months, but MST could not be calculated exactly because of the low failure rate during the study period. CONCLUSIONS: The resin-modified glass ionomer had the overall best performance of the two materials under comparison. The silver cermet material cannot be recommended for Class II restorations in primary teeth.