Dental Enamel

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The aim of this study was to assess in vitro the influence of the CO2 laser and of the type of ceramic bracket on the shear bond strength (SBS) to enamel. A total of 60 enamel test surfaces were obtained from bovine incisors and randomly assigned to two groups, according to the ceramic bracket used: Allure (A); Transcend (T). Each group was divided into 2 subgroups (n = 15): L, laser (10W, 3s); C, no laser, or control. Twenty-four hours after the bonding protocol using Transbond XT, SBS was tested at a crosshead speed of 0.5 mm/min in a universal testing machine. After debonding, the Adhesive Remnant Index (ARI) was evaluated at 10 x magnification and compared among the groups. Data were analyzed by one-way ANOVA, Tukey's, Mann-Whitney's and Kruskal-Wallis tests (α = 0.05). Mean SBS in MPa were: AL = 0.88 ± 0.84; AC = 12.22 ± 3.45; TL = 12.10 ± 5.11; TC = 17.71 ± 6.16. ARI analysis showed that 73% of the specimens presented the entire adhesive remaining on the tooth surfaces...

The aim of this study was to evaluate the effects of different techniques of surface treatment on the microleakage of fissure sealants in permanent molar teeth in vitro. 96 extracted impacted human third molars were randomly divided into 8 surface treatment groups (n=12/group) as 1. Er: YAG laser ; (Fidelis II, Fotona, Ljubljana, Slovenia) (125 mj, 20Hz) ; 2. Er: YAG laser + 37% H3PO4 (15s) ; 3. ER: AG laser + 37% H3PO4+Prime&Bond NT ; 4. Er: YAG laser + G Bond ; 5. Er: YAG laser + Prime&Bond NT ; 6. 37% H3PO4 ; 7. 37% H3PO4 + Prime&Bond NT ; 8. G Bond. Sealant material (Clinpro, 3M ESPE, Seefeld, Germany), was applied into the fissures and light-cured for 20s with LED (Bluephase C5, Ivoclar-Vivadent, Schaan, Liechtenstein). Specimens were subjected to thermocycling (1000×, 5-55°C, dwell time: 15s) and immersed in 0.5% basic fuchsin solution for 24h at 37°C. The samples were sectioned and scored on a 3 point rating scale using a light microscope with a magnification of ×20. One-way ...

The effect of gamma irradiation therapy on the ultimate tensile strength (UTS) of enamel and dentin in relation to prism orientation, dentin tubule orientation, and location is unknown. It was hypothesized that tubule and prism orientation, location, and irradiation have an effect on the UTS of dental structures. Forty human third molars were used, half of which were subjected to 60 Gy of gamma irradiation, in daily increments of 2 Gy. The specimens were evaluated by microtensile testing. Results showed that irradiation treatment significantly decreased the UTS of coronal and radicular dentin and of enamel, regardless of tubule or prism orientation. With or without irradiation, enamel was significantly stronger when tested parallel to its prismatic orientation. Coronal and radicular dentin of non-irradiated specimens presented significantly higher UTS when tested perpendicularly to tubule orientation. However, when the teeth were irradiated, the influence of tubule orientation disappeared, demonstrating that irradiation is more harmful to organic components.

In the early mineralized enamel crystals, ribbon-like crystals appear near the ameloblasts. Some ribbon-like crystals showed helical or spiral structure within restricted environment during the preparation of embryonic bovine specimens for electron microscope. These specimens did not suffer from the cutting damages nor staining effects. The main cause of the helix structure is considered a result of the dehydration during preparation. The periodic structure must reflect the regularity of initial enamel crystals. If dehydration caused the ribbon-like crystal to induce the periodic helix, it is one possibility that the earliest enamel crystal is OCP which has been proposed as a precursor of HA. Because it is considered that OCP is more sensitive to dehydration and more symmetric structure than biological HA. The periodicity of the helical ribbon-like structure was about 25 to 55 nm long and could be compared to the periodicity of organic helices which had observed in an immature rat enamel.

The aim of this study was to evaluate, in vitro, the effect of iron on the dissolution of bovine enamel powder, when added to two carbonated beverages.Powdered enamel was produced by griding enamel fragments of bovine incisor in a steel pestle and mortar. Particles between 75 and 106 μm were selected using appropriated meshes. At time zero, the carbonated beverage (Coke® or Sprite Zero®) was added to powdered enamel (1 mg enamel powder/10 μL of beverage) and vortexed for 30 s. The sample was immediately centrifuged (11,000 rpm) for 30 s and the supernatant was removed at 1 min 40 s. This procedure was repeated five times with the beverage containing increasing ferrous sulphate concentrations (1.25, 2.5, 5, 10, 15, 30 and 60 mmol/L). The phosphate released in the medium was analysed spectrophotometrically. Data were analysed using ANOVA and Tukey's test (p < 0.05).When iron at 30 and 60 mmol/L was added to Coke®, a significant reduction in the dissolution of powdered enamel was observed when compared to control (11 and 17%, respectively), while lower iron concentrations did not have any effect on enamel powder dissolution. Regarding Sprite Zero®, iron concentrations up to 10 mmol/L had no significant effect, while higher concentrations significantly increased enamel powder dissolution.The results suggest that iron can interfere with the dissolution of dental enamel powder in the presence of acidic beverages and the type of acid in these beverages seems to modulate this effect.

Amelogenin-mineral interactions were investigated using an in vitro binding approach. Rat incisor enamel matrix proteins (mainly amelogenins) were dissolved in synthetic enamel fluid and allowed to equilibrate with deproteinised developing enamel crystals. The results showed that amlogenin proteins of 21, 23, 24, 26 and 27-kDa (corresponding to nascent and partially degraded amelogenins) were associated with the crystals whilst the lower Mr amelogenins (&amp;lt; 21 KDa) remained free in the synthetic enamel fluid. These data suggest the nascent and partially degraded amelogenins may interact with developing enamel crystals and could influence their growth. Albumin-mineral interactions were investigated by extracting developing rat incisor enamel with synthetic enamel fluid. Insoluble material (including the enamel crystals) was then further extracted with 0.1 M phosphate buffer (pH 7.4) to desorb any mineral bound proteins. Western blotting using anti-albumin antibodies showed that almost all of the albumin from the secretory stage enamel and a significant proportion of the albumin present in early transition stage was extractable in the synthetic enamel fluid. However, synthetic enamel fluid did not extract albumin from late transition or maturation stage tissue, which could only be removed following further extraction with phosphate buffer. Albumin degradation was apparent during the transition and maturation stages, where it is degraded and ultimately removed. This binding pattern may be related to amelogenin degradation and removal during the transition stage, permitting albumin access to the previously obscured crystal surfaces. That the secretory stage matrix appears to &amp;quot;protect&amp;quot; secretory stage crystals from albumin may be an important consideration in the aetiology of enamel hypoplasias (i.e. incomplete crystal growth) and when using dissociative extraction procedures for the identification of mineral bound proteins.

Stress distribution in human tooth structure can be visualized through the use of Moiré fringes, which has improved the clinical understanding of recently identified anatomical structures in molar occlusal surfaces. This article discusses the concept of a &quot;peripheral rim of enamel&quot; and describes the manifestation of compressive and tensile fractures within the peripheral rim of enamel and dentin. It also emphasizes the benefits of microdentistry techniques and minimally invasive preparation designs in the long-term preservation of the natural tooth structure.

To evaluate Shear Bond Strength (SBS) values of different dental adhesives on Er:YAG laser prepared enamel and bur prepared enamel, one hundred and fifty bovine incisors were randomly assigned to SBS tests on enamel (n=15) in ten different groups. Groups 1 to 5 were prepared with Er:YAG laser. Groups 6 to 10 were mechanical prepared. Followed by: Group 1 and 6-37% phosphoric acid (PA) + ExciTE®; Group 2 and 7-AdheSE®; Group 3 and 8-FuturaBond® NR; Group 4 and 9-ExciTE®; Group 5 and 10-Xeno® V. After the adhesive systems samples were subjected to thermal cycling, SBS were performed in an universal testing machine at 5mm/min. Data were treated with two-way ANOVA, and post-hoc test (Student knewman keuls) (p<0,05). Chi-squared statistical tests were used to evaluate the type of fractures. Mean SBS values were Group 1-47

Hollow-core photonic-crystal fibres (PCFs) for the delivery of high-fluence laser radiation capable of ablating tooth enamel are developed. Sequences of picosecond pulses of 1.06 µm Nd:YAG-laser radiation with a total energy of about 2 mJ are transmitted through a hollow-core photonic-crystal fibre with a core diameter of approximately 14 µm and are focused on a tooth surface in vitro to ablate dental tissue. The hollow-core PCF is shown to support the single-fundamental-mode regime for 1.06 µm laser radiation, serving as a spatial filter and allowing the laser beam quality to be substantially improved. The same fibre is used to transmit emission from plasmas produced by laser pulses on the tooth surface in the backward direction for detection and optical diagnostics.

Objective: To evaluate whether the debonding procedure leads to restitutio ad integrum of the enamel surface by investigating the presence of enamel within the bracket base remnants after debonding. Materials and Methods: Sixty patients who completed orthodontic treatment with fixed appliances were included. A total of 1068 brackets were microphotographed; the brackets presenting some remnants on the base (n 5 818) were selected and analyzed with ImageJ software to measure the remnant area. From this population a statistically significant sample (n 5 100) was observed under a scanning electron microscope to check for the presence of enamel within the remnants. Energy dispersive x-ray spectrometry was also performed to obtain quantitative data. Results: Statistically significant differences in the remnant percentage between arches were observed for incisor and canine brackets (P , .0001 and P 5 .022, respectively). From a morphologic analysis of the scanning electron micrographs the bracket bases were categorized in 3 groups: group A, bases presenting a thin enamel coat (83%); group B, bases showing sizable enamel fragments (7%); group C, bases with no morphologic evidence of enamel presence (10%). Calcium presence was noted on all evaluated brackets under energy dispersive x-ray spectrometry. No significant difference was observed in the Ca/Si ratio between group A (16.21%) and group B (18.77%), whereas the Ca/Si ratio in group C (5.40%) was significantly lower than that of the other groups (P , .323 and P 5 .0001, respectively). Conclusion: The objective of an atraumatic debonding is not achieved yet; in some cases the damage could be clinically relevant. (Angle Orthod. 2013;83:885-891.) a Visiting Professor,

Objective: This investigation was performed to evaluate the acid resistance of lased enamel and dentin by Er,Cr:YSGG laser to artificial caries-like lesions by spectrophotometry, and the ultrastructure of lased areas was investigated by scanning el..tron microscopy (SEM) in vitro. Bockground Data: In recent years, many studies have been performed to evaluate the effects of Er,Cr:YSGG laser on dental hard tissues. However, there have been only a few studies to determine if this laser is suitable for caries preventive treatments. Meth ods: An Er,Cr:YSGG laser was used to irradiate the enamel or dentin samples from 30 extracted human mo lars at 6 W (67.9 J/cm 2) or 5 W (56.6 J/cm Z) pulse energy, respectively, with or without water mist. Samples _ were subjected to 2 ,ul of 0.1 M lactic acid solution (pH 4.8) for 24 h at 36°C. The parts per million (ppm) of cal cium ion (Ca H) dissolved in each solution was determined by atomic absorption spectrophotometery, and the morphological changes were investigated by SEM. Results: The lowest mean Ca H ppm was recorded in the lased samples. SEM observation showed that the Iased areas were melted and seemed to be thermally degener ated. After acid demineraUzation, the thermally degenerated enamel or dentin surfaces were almost un changed. Conclusions: The results of this study suggested that Er,Cr:YSGG laser irradiation with and without water mist appears to be effective for increasing acid resistance.

cement tested would be unlikely to affect the fit of any such prosthesis. Prostheses constructed in this manner would have the benefits of microretention without the technical problems of electrolytic etching. REFERENCES I. Rochette AL: Attachment of a splint to enamel of lower anterior teeth.

To evaluate the effect of an 8% arginine-calcium carbonate fluoride-free desensitizing paste on the surface roughness of resin composite, porcelain, amalgam, gold, and human dental enamel both prior to and following simulated toothbrushing. A resin composite (Filtek Supreme), a commercial porcelain (IPS Empress), an amalgam (Dispersalloy), gold (JIF-PF) and human dental enamel were used, as well as commercial finishing and polishing instruments. Eight two-sided samples were fabricated for each group. The composite and amalgam samples were stored at 100% relative humidity and 37 degrees C for 48 hours prior to measuring the surface roughness and completing the subsequent finishing and polishing procedures. Enamel blocks were cut from human lesion-free teeth and embedded in acrylic. The blocks were then polished flat with high polishing pastes. For gold and porcelain, the same size was used and the materials processed by a professional dental laboratory. Following storage, each surfac...

O sealant, UltraSeal XT ® hydro™ (Ultradent Products, USA), and to investigate its in vitro resistance to microleakage after placement on conventionally acid etched and sequentially lased and acid etched molars. Material and Methods: The sealant was characterised by Fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Vickers indentation test. Occlusal surfaces of extracted human molars were either conventionally acid etched (n=10), or sequentially acid etched and laser irradiated (n=10). UltraSeal XT ® hydro™ was applied to both groups of teeth which were then subjected to 2,500 thermocycles between 5 and 55°C prior to microleakage assessment by fuchsin dye penetration. Results: UltraSeal XT ® hydro™ is an acrylate-based sealant that achieved a degree of conversion of 50.6±2.2% and a Vickers microhardness of 24.2±1.5 under standard light curing (1,000 mWcm-2 for 20 s). Fluoride ion release is negligible within a 14-day period. SEM and EDX analyses indicated that the sealant comprises irregular submicron and nano-sized silicon-, barium-, and aluminium-bearing reduce microleakage (Mann-Whitney U test, p<0.001). The lased teeth presented enhanced

Amelogenin, the predominant matrix protein in developing dental enamel, has been considered essential for proper enamel formation . Amelogenin self-assembles into nanospheres that serve as a scaffold for the oriented elongation of enamel crystals. As enamel matures, amelogenin proteins are progressively processed by proteinases, including matrix metallopro-

Background: The perceptions of parents and children regarding oral health are useful to oral public health and clinical practice in pediatric dentistry. The primary aim of the present study was to evaluate the correlation between the total and item scores of the Scale of Oral Health Outcomes for Five-Year-Old Children (SOHO-5) (parental version and child's self-reports) and the Early Childhood Oral Health Impact Scale (ECOHIS). Subsequently, the discriminative validity of these assessment tools regarding dental caries was compared. Methods: One hundred twenty-one children randomly selected in the city of Diamantina (Brazil) were submitted to oral examinations. Parents answered the ECOHIS and SOHO-5p (parental version) and children answered the SOHO-5c (child's self-reports). Statistical analysis involved the Mann-Whitney test as well as the calculation of Spearman's correlation coefficients. Results: A significant correlation was found between the SOHO-5p and ECOHIS (r = 0.85), whereas no significant correlations were found between the SOHO-5c and SOHO-5p (r = 0.00) or between the SOHO-5c and ECOHIS (r = −0.41). Significant differences in the impact on quality of life were found between children with severe decay and no severe decay (caries free, with initial or established caries) both the ECOHIS and SOHO-5p (p ≤0.05), whereas no difference was found in SOHO-5c (p > 0.05). Conclusions: The ECOHIS and SOHO-5p were correlated with each other. The accounts of the children differed from their parents' reports and were not capable of discriminating dental caries in advanced stages of progression.

Dental caries is a complex disease process that afflicts a large proportion of the world&#39;s population, regardless of gender, age and ethnicity, although it does tend to affect more indivduals with a low socioeconomic status to a greater extent. The physicochemical properties of the mineral comprising the tooth surface and subsurface modulate the development, arrestment and remineralization of dental caries. Post-eruption maturation of enamel surfaces and exposed root surfaces is important in order for more susceptible mineral phases to be modified by incorporation of soluble fluoride from the plaque into dental hydroxyapatite. The chemical reactions that occur during acidic conditions when tooth mineral dissolves (critical pH) are determined by the supersaturation of calcium and phosphate within plaque and saliva, as well as if fluoride is present.

Background: The treatment of deep dental decay has traditionally involved removal of all the soft demineralized dentine before a filling is placed. However, this has been challenged in three groups of studies which involve sealing soft caries into the tooth. The three main groups either remove no caries and seal the decay into the tooth, remove minimal (ultraconservative) caries at the entrance to a cavity and seal the remaining caries in, or remove caries in stages over two visits some months apart to allow the pulp time to lay down reparative dentine (the stepwise excavation technique). Objectives: To test the null hypothesis of no difference in the incidence of damage or disease of the nerve of the tooth (pulp), progression of decay and longevity of restorations irrespective of whether the removal of decay had been minimal (ultraconservative) or complete. Search strategy: The Cochrane Oral Health Group Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, PubMed and EMBASE databases were searched. The reference lists in relevant papers were checked. Selection criteria: Randomized controlled trials and controlled clinical trials comparing minimal (ultraconservative) caries removal with complete caries removal in unrestored permanent and deciduous teeth. Data collection and analysis: Outcome measures recorded were exposure of the nerve of the tooth (pulp) Reproduced with permission of Ricketts DNJ, Kidd EAM, Innes N, Clarkson J. Complete or ultraconservative removal of decayed tissue in unfilled teeth. Cochrane Database of Systematic Reviews 2006, Issue 3.

Two commercially available dentine-adhesive systems, Tenure and Tripton, were tested in two different cavity designs by placing 132 Class V composite restorations in cervical lesions of 35 patients. In Group A, the cervical restorations were placed totally in dentine without any intentional enamel involvement. In Group B, they were placed in dentine with adjacent enamel margins bevelled and acid etched. The retention rate, the evidence of clinical microleakage, and the marginal integrity were monitored over a 2-year period. The results of this clinical investigation indicate a high failure rate when only dentinal bonding was involved. A loss rate of 30% for Tenure and 55% for Tripton was noted in Group A after 2 years of clinical service. However, both adhesive systems used in combination with micromechanical retention on the enamel border (Group B) performed extremely well with only one restoration each having debonded over the 2-year period. Identically, marginal integrity and evidence of clinical microleakage more severely deteriorated with time for the Group A restorations in comparison with their Group B counterparts. In summary, the overall results were more positive for Tenure than for Tripton. It is concluded that micromechanical retention by acid etching of the enamel margin is still indispensable for the clinical success of cervical Class V composite restorations, primarily for retention and clinical microleakage and also, but to a lesser degree, for marginal adaptation.

The purpose of this study was to compare the retention of circlet (E) clasps and back-action clasps against three abutment surface materials during long-term simulation of attachment and detachment. Forty-eight test models were constructed by placing premolars (natural abutments or metal dies) inside metal blocks to test different abutment retention surface materials (sound enamel, composite resin, and glass-ceramic; 16 each). The models were duplicated into investment models for construction of circlet (E) and back-action clasps. Removal and insertion cycling of clasps was carried out for 250, 500, 1000, 2000, 4000, 8000, and 16,000 cycles. The retention of each clasp was measured before cycling and after each interval. Data were analyzed using 1-way-ANOVA, 2-way-ANOVA, and Mann-Whitney U tests. No significant differences in retention of either clasp were found between the three abutment material surfaces; however, there was a significant decrease in retention force of the circlet (E) clasp between 1000 and 2000 cycles but not of the back-action clasp. (1) The back-action clasp maintains its retention force for a longer period than the circlet (E) clasp. (2) Composite resin contouring of teeth provided retention comparable to enamel and a ceramic material.

The aim of this study was to evaluate two-body wear of five indirect composites and compare them with enamel. Signum, belleGlass HP, SR Adoro, Dialog, GC Gradia and enamel were formed into cylinders (n = 10). Two-body abrasive wear rates were determined using a porcelain disk and a pin on disk apparatus. The height and weight loss of the specimens were measured by stereomicroscope and digital scale. The data were subjected to analysis of variance and Tukey HSD tests to determine significant differences (alpha = 0.05). GC Gradia showed significantly less wear resistance than the other materials. Enamel was more resistant than any of the tested composites. Within the limitations of this study it can be concluded that the type of resin, filler size and method of polymerization could have affect the two-body abrasion resistance of indirect composites.

Adhesive procedures are essential to most restorative protocols used in modern dentistry. Increasing demand and constant interest in new products have stimulated dental manufacturers to produce new adhesive systems and marketing campaigns that announce fast and easy bonding. However, laboratorial and clinical studies show that, usually, ease of application of an adhesive system does not relate to its competence in creating a quality, long-term adhesive interface. This article will present relevant data from the scientific literature to help clinicians understand quality adhesion and achieve excellent results with the current adhesion systems.

There are numerous dentine bonding agents c u r r e n t l y on the market, the majority of which adhere by means of infiltration of a hydrophilic p o l y m e r i z a b l e diacrylate into dentinal collagen exposed by acid treatment. The purpose of the present study was to evaluate the clinical performance of one such product, EBS dentine bonding, in nonundercut caries-free cervical lesions. Forty cavities were restored in eight patients of mean age 53 years. The manufacturer's instructions were followed, which involved essentially etching the enamel and dentine for 20 seconds with 32 per cent phosphoric acid, application and evaporation of EBS Primer, followed by placement and curing of EBS Bond, and restoring the cavity with Pertac II (ESPE) hybrid resin composite. Restorations were photographed at base line and one year for evaluation of marginal discolouration on a continuous linear rating scale. A t six months, one patient with four restorations was not available; the remaining 36 restorations were all present. At one year, one restoration was missing, giving a cumulative retention rate of over 97 per cent. One of the 36 restorations exhibited very mild marginal discolouration.

Objective: Resin infiltration is considered as a treatment option for initial caries lesions. As cavitated early lesions might require additional restorative intervention, a caries infiltrant might be also used for enamel conditioning prior to composite insertion. This study aimed to analyse the shear bond strength of a flowable composite to sound and demineralised enamel pretreated with a caries infiltrant, a conventional adhesive or a combination of both.

Objectives. To describe CO 2 laser characteristics and to review the literature regarding its effects on caries inhibition in enamel and dentin. Another aim of this review is to discuss the effects of CO 2 laser in combination with fluoride.

To compare the prevalence and severity of developmental defects of enamel (DDE) among subjects whose maxillary incisors developed during periods with different concentrations of fluoride in the public water supply. Standardized intra-oral photographs of random samples of 12-year-old children were collected in 1983, 1991 and 2001 (n = 1,990) in Hong Kong and assessed for DDE by a trained masked examiner. The fluoride concentrations in the public water supply at the times when the enamel on their maxillary incisors developed were 1.0, 0.7 and 0.5 ppm, respectively. The mouth prevalence of DDE for these children (based on the maxillary incisors) were 92.1, 55.8 and 35.2% in the years 1983, 1991 and 2001, respectively (p &amp;amp;amp;lt; 0.001). Most of these children were affected by diffuse opacities (89.3% in 1983, 48.5% in 1991 and 32.4% in 2001, p &amp;amp;amp;lt; 0.001). Marked differences in the mean number of teeth affected by DDE (p &amp;amp;amp;lt; 0.001) and in the maximum extent of DDE (p &amp;amp;amp;lt;or= 0.002) between 1983, 1991 and 2001 were also observed. A decrease in the prevalence and severity of DDE among the maxillary incisor teeth of the children corresponded to the reductions in the concentration of fluoride in the water during the time of enamel development.

More than five hundred million direct dental restorations are placed each year worldwide. In about 55% of the cases, resin composites or compomers are used, and in 45% amalgam. The longevity of posterior resin restorations is well documented. However, data on resin composites that are placed without enamel/dentin conditioning and resin composites placed with self-etching adhesive systems are missing. The database SCOPUS was searched for clinical trials on posterior resin composites without restricting the search to the year of publication. The inclusion criteria were: (1) prospective clinical trial with at least 2 years of observation; (2) minimum number of restorations at last recall = 20; (3) report on dropout rate; (4) report of operative technique and materials used; (5) utilization of Ryge or modified Ryge evaluation criteria. For amalgam, only those studies were included that directly compared composite resin restorations with amalgam. For the statistical analysis, a linear mi...

A new, highly filled primer is currently marketed as a fluoride delivery system effective in reducing white spot lesions in orthodontic patients. However, no studies in the literature support this claim. The purpose of this in-vivo study was to investigate the retention and the efficacy of this primer in reducing the formation of white spot lesions. In each patient for whom premolar extractions were planned (n = 22), 1 premolar was randomly chosen as the experimental tooth for the application of the fluoride delivery system (Opal Seal; Ultradent Products, South Jordan, Utah), and the contralateral tooth was assigned as the control to receive the standard treatment (Transbond XT; 3M Unitek, Monrovia, Calif). After the bonding procedures, separators were placed around the premolar brackets to encourage plaque retention over 8 weeks. After the extractions, the tooth surfaces were evaluated visually and with microhardness techniques for demineralization. Primer retention was also invest...

Tunnel restorations (n=161) performed by 4 dentists were evaluated after a mean of 35 months in situ. Demineralized enamel was to be spared during preparation. The preparations were filled with a cermet glass ionomer (polyalkenoate) cement. Evaluation was carried out using clinical and radiographical criteria. During the observation period, approximately 16% of the restorations were replaced due to caries in dentin and 14% due to marginal ridge fracture. Cavitation in the approximal surface and/or increased radiolucency of the approximal enamel were observed in 34% of the remaining tunnel-restored teeth. A significantly higher frequency of failures were registered when treating patients with a high caries activity, where the initial lesion was large, and where the restoration did not reach the approximal surface.