Biomedical subjects

Bart Van Meerbeek

Publications and source records attributed to Bart Van Meerbeek.

At least 19 recordsLinked to original sources

PubMed2007

Bonding to ground versus unground enamel in fluorosed teeth.

OBJECTIVES: To determine the effect of grinding on the bonding effectiveness of a self-etch and an etch-and-rinse adhesive to fluorosed enamel. METHODS: The teeth were classified using the Thylstrup and Fejerskov index (TFI). Fluorosed teeth (TFI=5) obtained from Isparta (Turkey) and control teeth (TFI=0) obtained from Leuven (Belgium) were used. Using a depth-marking diamond bur, 0.3mm of enamel was removed from mid-buccal and mid-palatal/lingual surfaces of the teeth, whereas the area adjacent to the ground area was left unprepared. A two-step self-etch (Clearfil Protect Bond, Kuraray) and a three-step etch-and-rinse adhesive (Optibond FL, Kerr) were used to bond the resin composite to the ground and unground enamel. Rectangular micro-specimens were prepared using the slow-speed diamond saw and tested in tensile to determine the micro-tensile bond strength (microTBS). RESULTS: The microTBS to unground fluorosed enamel was significantly lower than to ground fluorosed enamel for Clearfil Protect Bond (15.8+/-15.2 and 45.0+/-12.4MPa, p<0.0001) and for Optibond FL (35.5+/-21.4 and 50.5+/-12.3MPa, p<0.05), respectively. In control teeth, Clearfil Protect Bond bonded better to ground enamel (p<0.01), whereas OptiBond FL exhibited a similar bonding effectiveness to ground and unground enamel (p=0.0634). SIGNIFICANCE: Preparation of enamel improved the resin-enamel bond strength in fluorosed teeth. The bonding effectiveness to unground enamel was lower in fluorosed teeth than in control teeth for the self-etch adhesive tested.

Adhesives↗

PubMed2006

NaOCl degradation of a HEMA-free all-in-one adhesive bonded to enamel and dentin following two air-blowing techniques.

OBJECTIVE: Phase-separation within HEMA-free all-in-one dental adhesives may result in the entrapment of droplets within the adhesive resin. Strongly air-blowing prior to polymerization, can remove most of these droplets. The objective of this study was to evaluate the effect these droplets may have on the resistance of the adhesive-tooth interface to NaOCl degradation. METHODS: The micro-tensile bond strength (microTBS) to enamel and dentin was determined when a HEMA-free all-in-one adhesive was applied either following a mild or strong air-blowing technique. The bonds were also exposed to an aqueous sodium hypochlorite (NaOCl) solution for 1h, following a recently introduced methodology to mimic in vivo bond degradation. RESULTS: This study revealed that strong air-blowing of the adhesive only resulted in a significantly higher micro-tensile bond strength (microTBS) to dentin, but not to enamel. Likewise, NaOCl only reduced the microTBS to dentin for both the mild and strong air-blowing technique, but again not the microTBS to enamel. Failure analysis by SEM clearly revealed that strong air-blowing is less effective in droplet removal when the adhesive was applied in small and narrow class-I cavities, as compared to when it was applied to flat surfaces. CONCLUSIONS: NaOCl did preferentially dissolve the hybrid layer at dentin, and more for the mild than for the strong air-blowing technique. A strong air-blowing procedure resulted in a more NaOCl-resistant hybrid layer, so that it can be concluded that a HEMA-free one-step adhesive definitely benefits from a strong air-blowing technique.

Air↗

PubMed2006

How to simulate wear? Overview of existing methods.

OBJECTIVES: The aim of the overview is to critically analyse the contributing factors to the biological wear process and to screen the wear simulators in dentistry for their capacity to mimic the wear conditions. An overview of the types of wear, grouped as biotribocorrosion, combined with a description of the different wear simulating devices will allow us to better understand the multifactorial nature of wear. METHODS: A search on keywords highlights the most common in-vitro wear simulators and their use in the laboratories for various simulation applications. RESULTS: Wear is a complex process that can hardly be simulated while controlling all variables. Especially the extrapolation of the in-vitro wear results to the in-vivo situation is difficult because there is a lot of interplay with biological factors that are difficult to mimic. SIGNIFICANCE: It is not the degree of sophistication, but the right mix of controllable variables that will make a wear simulator predictive.

Dental Materials↗

PubMed2006

Effect of 4-MET- and 10-MDP-based primers on resin bonding to titanium.

The purpose of this study was to investigate the effect of a 4-MET- and 10-MDP-based primer on the bond strength of two resin cements (SuperBond C&B, Sun Medical; Panavia Fluoro Cement, Kuraray) to titanium (Ti). Ti plates were treated with six experimental primers consisting of, respectively, 10-MDP and 4-MET in concentrations of 0.1, 1 and 10wt%, or were kept untreated (control). The highest tensile bond strength of Panavia Fluoro Cement to Ti was obtained when the Ti surface was pre-treated with 10wt% 10-MDP and was significantly higher than that when a lower concentrated 10-MDP-based primer or any 4-MET-based primer was used. On the contrary, no significant difference in tensile bond strength of SuperBond C&B was found for the untreated and six pre-treated Ti surfaces, although pre-treatment with each 10-MDP-based primer resulted in a higher tensile bond strength as compared to any 4-MET pre-treatment. Altogether, the data obtained strongly suggest that 10-MDP is effective to improve the adhesive performance of resin to titanium.

Dentin-Bonding Agents↗

PubMed2005

Effect of surface pre-treatment on durability of resin-based cements bonded to titanium.

OBJECTIVES: Titanium has in recent years become a material of great opportunities in dentistry and orthopedics. In this study, we searched for a method to effectively pre-treat titanium as part of an adhesive luting and/or resin-veneering procedure. METHODS: Ti plates were treated with two different solutions of hydrochloric acid (0.1, 1N), 37wt% phosphoric acid or kept untreated (control). The tensile bond strength of the composite cement (Panavia Fluoro Cement, Kuraray) to the untreated and pre-treated Ti plates was determined without and after 20,000 thermo-cycles. XPS was used to chemically analyze the effect of the three Ti pre-treatments, as well as the interaction of 10-methacryloxydecyl dihydrogen phosphate (10-MDP; functional monomer of Panavia Fluoro Cement) with Ti treated with 1N HCl. RESULTS: Although no significant difference in immediate tensile bond strength was measured, thermo-cycling significantly decreased the bond strength of all experimental groups except for Ti treated with 1N HCl. No difference in surface roughness was found between untreated and treated Ti. XPS demonstrated that HCl effectively decontaminated Ti in a dose-dependent manner, while H(3)PO(4) was strongly adsorbed on the Ti surface. While the latter potentially inhibits adsorption of the phosphoric groups of the functional monomer 10-MDP, Ti pre-treated with 1N HCl improved the adsorption of 10-MDP as compared to untreated Ti. SIGNIFICANCE: It is concluded that 1N HCl effectively pre-treats Ti in order to make it more receptive to resin, while H(3)PO(4) should better not be used.

Acid Etching, Dental↗

PubMed2005

Micro-tensile bond strength of adhesives bonded to Class-I cavity-bottom dentin after thermo-cycling.

UNLABELLED: A widely used artificial aging methodology is thermo-cycling. The ISO TR 11450 standard (1994) recommends 500 cycles in water between 5 and 55 degrees C. Recent literature revealed that more cycles are needed to mimic long-term bonding effectiveness. Furthermore, the artificial aging effect induced by thermo-cycling is not clearly established. Two underlying mechanisms can be advanced: (1) hot water may accelerate hydrolysis and elution of interface components and (2) repetitive contraction/expansion stress can be generated. OBJECTIVES: The purpose of this study was to evaluate the relative contribution of both chemical (hydrolysis and elution of interface components) and mechanical (repetitive contraction/expansion stress) degradation pathways on the thermo-cycling-induced artificial aging of dentin-adhesive interfaces at the bottom of class-I cavities. METHODS: The micro-tensile bond strength (muTBS) of contemporary adhesives (a three-step etch and rinse, a two-step and a one-step self-etch adhesive) bonded to class-I cavity-bottom dentin was determined after 20,000 cycles as well as after 20 days of water storage (control). Restored class-I cavities (repetitive contraction/expansion stress) as well as prepared micro-specimens (diffusion-dependent hydrolysis and elution) were subjected to the thermo-cycling regimen. RESULTS: Thermo-cycling did not enhance chemical or mechanical degradation of the bonds produced by a two-step self-etch and a three-step etch and rinse adhesive to dentin. The one-step self-etch adhesive tested was, however, not able to withstand polymerization shrinkage stress, nor thermo-cycling, when applied in class-I cavities. SIGNIFICANCE: Thermo-cycling results in combined contraction/expansion stress and accelerated chemical degradation. However, the relative contribution of each is strongly dependent on the specific test set-up and the adhesive used.

Analysis of Variance↗

PubMed2005

Effect of evaporation of primer components on ultimate tensile strengths of primer-adhesive mixture.

OBJECTIVE: The purpose of the present study was to evaluate the effect of evaporation of primer components on the ultimate tensile strength (UTS) of primer-adhesive mixtures. METHODS: The UTSs of 1:3 by weight primer-adhesive mixtures and of the pure adhesives (controls) were measured after 0-, 2-, 5-min and 24-h storage in a 37 degrees C oven for the three-step etch&rinse adhesive OptiBond FL (Kerr) and the two-step self-etch adhesive Clearfil SE (Kuraray). RESULTS: Evaporation of primer components increased with time for both adhesives investigated. OptiBond FL showed a higher evaporation of primer components than Clearfil SE at the 2-, 5-min and 24-h storage time. As compared to the pure adhesive, the UTS of the primer-adhesive mixture was lower after 0- and 2-min storage for OptiBond FL and after 0-, 2- and 5-min storage for Clearfil SE. The UTS of OptiBond FL was higher than that of Clearfil SE at the 0- and 2-min storage time, though there was no difference at the 5-min and 24-h storage time. SIGNIFICANCE: The degree of evaporation of primer components depended largely on the primer solvents employed. The significant decrease in UTS of adhesive resin when mixed with primer must be attributed to incomplete evaporation of primer components. Complete evaporation of solvents is hard to achieve, even by thorough air drying.

Adhesives↗

PubMed2005

Effect of cavity configuration and aging on the bonding effectiveness of six adhesives to dentin.

OBJECTIVES: The purpose of this study was to determine the effect polymerization contraction stress may have on bond durability. METHODS: Bonding effectiveness was assessed by micro-tensile bond strength testing (muTBS) and electron microscopy. The muTBS to flat dentin surfaces and in standardized cavities was determined (this after 1 day as well as 1 year water storage). Six adhesives representing all current classes were applied: two etch-and-rinse (OptiBond FL, Kerr; Scotchbond 1, 3M ESPE), two self-etch (Clearfil SE Bond, Kuraray; Adper Prompt, 3M ESPE) and two glass-ionomer (Fuji Bond LC, GC; Reactmer, Shofu) adhesives. RESULTS: The conventional 3-step etch-and-rinse adhesive OptiBond FL bonded most effectively to dentin, and appeared insensitive to polymerization shrinkage stress and water degradation. The 2-step self-etch adhesive Clearfil SE Bond most closely approached this superior bonding effectiveness and only slightly lost bond strength after 1-year water exposure. The 2-step etch-and-rinse adhesive Scotchbond 1 and the 'strong' 1-step self-etch adhesive Adper Prompt appeared very sensitive to cavity configuration and water-aging effects. The 2-step resin-modified glass-ionomer adhesive Fuji Bond LC only suffered from shrinkage stress, but not from 1-year water-exposure. Remarkable also is the apparent repairability of the 'mild' 1-step glass-ionomer adhesive Reactmer when stored for 1 year in water, in spite of the very low 1-day muTBS. SIGNIFICANCE: Simplified bonding procedures do not necessarily imply improved bonding performance, especially in the long term.

Acid Etching, Dental↗

PubMed2005

A randomized controlled study evaluating the effectiveness of a two-step self-etch adhesive with and without selective phosphoric-acid etching of enamel.

OBJECTIVES: The purpose of this randomized controlled clinical trial was to test the hypothesis that a two-step self-etch approach is equally effective to restore cervical class-V lesions as a self-etch approach with beforehand selective etching of enamel using phosphoric acid. METHODS: Twenty-nine patients received two or four restorations randomly following two experimental protocols ('paired-tooth' study design): (1) A 'mild' self-etch adhesive (Clearfil SE, Kuraray) was applied following a self-etch approach on both enamel and dentin (C-SE non-etch); (2) Similar application of Clearfil SE, but including beforehand selective acid-etching of the enamel cavity margins with 40% phosphoric acid (C-SE etch). Clearfil AP-X (Kuraray) was used as restorative composite for all 100 restorations. The clinical effectiveness was recorded in terms of retention, marginal integrity and clinical micro-leakage after 2 years of clinical service. RESULTS: No restoration losses were recorded. Clinical micro-leakage was slight and only rarely observed. No significant differences were found between both groups for the diverse parameters evaluated except for the number of small incisal marginal defects, which was significantly higher in the C-SE non-etch group (McNemar: p = 0.0391). SIGNIFICANCE: The clinical effectiveness of the mild two-step self-etch adhesive Clearfil SE was excellent after 2 years of clinical service. Although in general no difference in clinical performance was recorded when Clearfil SE was applied following either of the experimental protocols, more marginal defects at the enamel side were noticed when enamel was not beforehand etched with phosphoric acid. However, these defects were small and of clinically negligible relevance.

Acid Etching, Dental↗

PubMed2005

Effect of fracture strength of primer-adhesive mixture on bonding effectiveness.

OBJECTIVE: The purpose of this study was to measure the micro-tensile bond strength (microTBS) of two adhesives to dentin and to correlate this microTBS with the micro-tensile fracture strength (microTFS) of primer-adhesive mixtures of the two adhesives. METHODS: The three-step etch&rinse adhesive OptiBond FL (Kerr) and the two-step self-etch adhesive Clearfil SE Bond (Kuraray) were used to bond Filtek Z100 (3M ESPE) to twenty mid-coronal dentin surfaces. The microTBS was determined at 1 and 24 h after light-curing. In addition, the microTFS of primer-adhesive mixtures (primer:adhesive=1:3 by weight) and of the pure adhesives (controls) were measured after the same time intervals. RESULTS: The microTBS to dentin of OptiBond FL at 24 h was significantly higher than at 1 h and than the microTBS of Clearfil SE Bond at 24 h. The mean microTFS of the primer-adhesive mixtures was always lower than the microTFS of the respective adhesives. The highest reduction in microTFS due to mixing primer with the adhesive resin was measured for Clearfil SE Bond. Both the microTFS of the primer-adhesive mixtures and the pure adhesives of OptiBond FL and Clearfil SE Bond increased with time. SIGNIFICANCE: The early 1 h microTBS to dentin was lower than the 24 h microTBS for OptiBond FL, but not for Clearfil SE Bond. Differences in polymerization efficiency as well as in the resulting interfacial strength may explain such varying early bond strengths to dentin.

Composite Resins↗

PubMed2005

Fatigue resistance of dentin/composite interfaces with an additional intermediate elastic layer.

According to the "elastic bonding" concept, a thick intermediate layer of flexible resin has been suggested to absorb part of the polymerization shrinkage stress and to absorb shocks during function. In this study, the effect of an additional intermediate layer of a low-viscosity resin on the microrotary fatigue resistance (microRFR) of a hybrid composite bonded to dentin was evaluated. The hypotheses tested were that an intermediate layer of a low-viscosity resin (i) increases the microRFR to dentin, but (ii) has no effect on the static bond strength. Microtensile bond strength (microTBS) samples were loaded until failure or inserted in a microrotary fatigue testing device. Specimens were tested at 4 Hz until failure or until 10(5) cycles were reached. An additional intermediate elastic layer had no effect on the static microTBS, but significantly lowered the median microRFR from 28.4 MPa to 21.6 MPa. However, the application of an intermediate flexible layer had, no effect on the static microTBS. In conclusion, an additional elastic intermediate layer did decrease significantly the microRFR (rejection of hypothesis i), but did not alter the microTBS (acceptance of hypothesis ii). The decrease in microRFR most likely may be explained by the lower mechanical properties of the intermediary layer.

Composite Resins↗

PubMed2005

In vivo degradation of resin-dentin bonds produced by a self-etch and an etch-and-rinse adhesive.

Resin-dentin bonds are known to degrade in the relatively aggressive oral environment. In order to obtain greater insight into the interfacial degradation process, we examined, by using transmission electron microscopy (TEM), the interfacial ultrastructure of two adhesives bonded to dentin after 1 yr in vivo. Class V cavities were prepared on the buccal surfaces of 14 intact teeth of two monkeys and then restored by using either the two-step self-etch adhesive, Unifil Bond, or the two-step etch-and-rinse adhesive, Single Bond, in combination with the restorative microhybrid composite, Z250. After 1 yr, 10 other teeth were restored by using the same materials (controls). One day later, the monkeys were killed, following which the microtensile bond strength to dentin was determined and the interfacial ultrastructure was examined by TEM. Whereas no noticeable changes in the morphology of the resin-dentin interface were observed between the 1-d and 1-yr specimens for Unifil Bond, Single Bond exhibited signs of interfacial degradation, in particular at the bottom of the 3 microm-deep hybrid layer. In conclusion, the adhesive interface produced by the etch-and-rinse adhesive was less resistant to degradation than that produced by the self-etch system.

Acid Etching, Dental↗

PubMed2005

Three-year clinical effectiveness of a two-step self-etch adhesive in cervical lesions.

A 3-yr randomized, controlled prospective study evaluated the clinical effectiveness of a mild two-step self-etch adhesive, Clearfil SE, in Class-V non-carious lesions. The hypothesis tested was that prior selective etching of enamel with phosphoric acid does not affect the 3-yr clinical performance of this adhesive. A total of 100 lesions in 29 patients were randomly restored in one or two pairs, according to two experimental protocols: (i) application of Clearfil SE according to the instructions of the manufacturer (C-SE non-etch); and (ii) similar application of Clearfil SE with prior etching of enamel cavity margins with phosphoric acid (C-SE etch). Clearfil AP-X was used as a restorative material. At 3 yr, 90% of the restorations were examined for retention, marginal integrity, marginal discoloration, caries recurrence, postoperative sensitivity, and preservation of tooth vitality. An excellent retention rate (100%) was noted after 3 yr of clinical functioning. Only one restoration of the C-SE etch group was clinically unacceptable owing to the presence of a severe cervical marginal defect. A pairwise comparison between both groups showed a significant difference only in the number of small marginal defects at the enamel side, which was higher in the C-SE non-etch group. These incisal defects were small and clinically irrelevant. Superficial marginal discoloration increased slightly in the C-SE non-etch group and was related to the higher frequency of small incisal marginal defects. In this latter group, localized marginal discoloration was observed significantly more in smokers. In conclusion, the clinical performance of the mild two-step self-etch adhesive, Clearfil SE, remained excellent after 3 yr of clinical functioning. Additional etching of the enamel cavity margins was not critical for its clinical performance.

Acid Etching, Dental↗

PubMed2005

Technique-sensitivity of contemporary adhesives.

Besides micro-mechanical interlocking through hybrid-layer formation, self-etch adhesives may benefit from additional chemical interaction between the functional monomer and residual hydroxyapatite. One-step adhesives are commonly associated with lower bonding effectiveness, which must be attributed in part to the dissolution of hydrophilic and hydrophobic monomers in a relatively highly concentrated solvent. In this 'difficult' mixture, also water is essential as ionization medium to enable self-etching activity. Due to the high hydrophilicity, one-step self-etch adhesives have been reported to behave as semi-permeable membranes, allowing fluids to pass through and seriously jeopardizing bond durability. Recent research has also revealed that HEMA-free one-step adhesives are prone to phase-separation, which may also account for their lower bonding effectiveness. Employing an appropriate air-drying technique may, however, improve the bonding effectiveness of such phase-separating adhesives by getting rid of substantially more interfacial water than HEMA-containing adhesives, of which water might be more difficult to remove from.

Acid Etching, Dental↗

PubMed2005

Effect of polymerization shrinkage on the sealing capacity of resin fillers for endodontic use.

PURPOSE: Recently, highly flowable resin fillers have been proposed for filling root canals using a single-cone approach. The purpose of this study was to test the hypothesis that polymerization shrinkage, which is inherent to this type of filler, can break the close initial contact between the main core and the surrounding dentin even if root dentin infiltration has occurred. MATERIALS AND METHODS: Twenty roots of anterior teeth were prepared chemomechanically and divided into 4 groups of 5 samples each. Groups 1 and 2: hydrophilic resin filler injected and spread, roots sectioned after setting; group 3: hydrophilic resin filler injected and spread, dental substrate dissolved after setting; group 4: hydrophobic resin sealer lentulo-spiraled and spread, roots sectioned after setting (as control). In groups 1, 2, and 3 the material was used following manufacturer's instructions. The section surfaces of groups 1 and 4, and the resin components of group 3 were processed for conventional FE-SEM. The section surfaces of group 2 were observed successively under environmental and high-vacuum conditions. RESULTS: Microscopic examination of the resin-dentin interfaces of groups 1 and 2 showed the existence of resin-dentin interdiffusion zones (RDIZ); however, the close initial contact between the main core and the surrounding dentin was often lost. In group 3, resin tag morphology was well characterized. Identical morphological features were observed in the resin-dentin interfaces in group 4. CONCLUSION: Since the existence of resin tags did not exclude the existence of a gap between the main core and the adjacent RDIZ, our results confirmed the proposed hypothesis.

Composite Resins↗

PubMed2004

Bonding of an auto-adhesive luting material to enamel and dentin.

OBJECTIVES: The objectives of this study were (1) to assess the bonding performance of a new auto-adhesive cement (RelyX Unicem, 3M ESPE) to enamel and dentin, using a standard micro-tensile bond strength (microTBS) test set-up, and (2) to evaluate the interaction of this material with dentin by means of high-resolution electron microscopy. METHODS: The microTBS of RelyX Unicem with and without prior acid etching was determined to enamel and dentin after 24 h of water storage and compared to the bonding effectiveness of the control cement (Panavia-F, Kuraray). In addition, diamond-knife cut interfaces of RelyX Unicem and Panavia-F bonded to dentin were examined using field-emission scanning (Fe-SEM) and transmission electron microscopy (TEM). RESULTS: The microTBS of RelyX Unicem to enamel was significantly lower than that of the control cement, whereas no significant difference was found when both cements were bonded to dentin. Acid etching prior to the application of RelyX Unicem raised the enamel microTBS to the same level as that of the control, but was detrimental for the dentin bonding effectiveness. The latter must be attributed to inadequate infiltration of the collagen mesh as revealed by Fe-SEM and TEM. Morphological evaluation additionally revealed that RelyX Unicem only superficially interacted with enamel and dentin, and that application using some pressure is required to ensure close adaptation of the cement to the cavity wall. SIGNIFICANCE: (1) RelyX Unicem should always be applied with some pressure, to ensure that the relatively high viscous cement intimately adapts to the cavity wall; (2) The cement only interacted superficially with dentin and enamel; (3) The best bonding effectiveness with this new auto-adhesive cement was obtained by selectively acid-etching enamel prior to luting.

Acid Etching, Dental↗

PubMed2004

Four-year water degradation of a resin-modified glass-ionomer adhesive bonded to dentin.

Glass-ionomers are auto-adhesive to tooth tissue through combined micro-mechanical and chemical bonding. How much each of the two bonding components contributes to the actual bonding effectiveness is, however, not known and there is not much information available on long-term stability. The objective of this study was to assess the bonding effectiveness of a resin-modified glass-ionomer adhesive to dentin after 4 yr of water storage. Fuji Bond LC (GC) was applied without (i) and with pretreatment using (ii) a polyalkenoic acid conditioner and (iii) a 37.5% phosphoric acid etchant. The etchant was used to exclude any chemical interaction with hydroxyapatite. The micro-tensile bond strength ( microTBS) to dentin decreased significantly over the 4 yr period in all three experimental groups. After 24 h and 4 yr, the lowest micro TBS was recorded when dentin was not pretreated. The highest micro TBS was obtained following polyalkenoic acid pretreatment, although this was not significantly different from specimens that were pretreated using phosphoric acid. Pretreating dentin with phosphoric acid intensified micromechanical interlocking at the expense of chemical bonding potential to hydroxyapatite. Nevertheless, correlating the micro TBS data with failure analysis through scanning electron microscopy and transmission electron microscopy indicated that combined micro-mechanical and chemical bonding involving pretreatment with the polyalkenoic acid conditioner yielded the most durable bond.

Acid Etching, Dental↗

PubMed2004

A prospective ten-year clinical trial of porcelain veneers.

PURPOSE: The aim of this in vivo study was to evaluate the clinical performance of porcelain veneers after 5 and 10 years of clinical service. MATERIALS AND METHODS: A single operator placed porcelain laminates on 87 maxillary anterior teeth in 25 patients. All restorations were recalled at 5 years and 93% of the restorations at 10 years. Clinical performance was assessed in terms of esthetics, marginal integrity, retention, clinical microleakage, caries recurrence, fracture, vitality, and patient satisfaction. Failures were recorded either as "clinically unacceptable but repairable" or as "clinically unacceptable with replacement needed". RESULTS: Porcelain veneers maintained their esthetic appearance after 10 years of clinical service. None of the veneers were lost. The percentage of restorations that remained "clinically acceptable" (without need for intervention) significantly decreased from an average of 92% (95 CI: 90% to 94%) at 5 years to 64% (95 CI: 51% to 77%) at 10 years. Fractures of porcelain (11%) and large marginal defects (20%) were the main reason for failure. Marginal defects were especially noticed at locations where the veneer ended in an existing composite filling. At such vulnerable locations, severe marginal discoloration (19%) and caries recurrence (10%) were frequently observed. Most of the restorations that present one or more "clinically unacceptable" problems (28%) were repairable. Only 4% of the restorations needed to be replaced at the 10-year recall. CONCLUSION: It was concluded that labial porcelain veneers represent a reliable, effective procedure for conservative treatment of unesthetic anterior teeth. Occlusion, preparation design, presence of composite fillings, and the adhesive used to bond veneers to tooth substrate are covariables that contribute to the clinical outcome of these restorations in the long-term.

Adult↗