Quintessence International, 07/2007

Classic bonded indirect restorations are laboratory fabricated and require 2 appointments: one for provisionalization and one for luting. This article describes the adhesive luting procedure, from try-in of the workpiece to finishing and polishing after the adhesive cementation, and it represents the second part of an updated technique for bonded inlays and onlays. The clinical sequence is described step by step with 2 cases. Particular attention is given to the adhesive treatment of the restoration and the cavity as well as the choice of the resin cement. Following the adhesive philosophy and due to improvements in materials and techniques, the simplified approach described may provide predictable luting restoration of the posterior dentition. Keywords: adhesive luting, indirect restoration, resin composite

Objectives: To analyze the change in pattern of plaque accumulation on buccal and occlusal surfaces of permanent teeth and associated variables in a cohort of 4,468 children examined on a yearly basis between the ages of 7 and 12 years. Method and Materials: Oral hygiene level on buccal surfaces was assessed using the Plaque Index of Silness and Loe; for occlusal surfaces, a simplified version of the index as described by Carvalho et al was used. Data on oral health habits were collected using questionnaires completed by the parents and by the school health care center. Multiple ordinal logistic regression models using first-order generalized estimating equations were fitted to estimate population average effects taking into account the correlated structure of the data. Results: Girls brushed significantly more frequently than boys (as reported by the parents) and presented with significantly less dental plaque. In all survey years, starting to brush at a young age, no daily consumption of sugar-containing drinks, and brushing at least twice a day were significantly associated with lower plaque accumulation scores. Parental help did not seem to influence the accumulation of occlusal plaque, but it did influence the amount of buccal plaque on incisors and premolars at older ages. The presence of sealants was significantly associated with less dental plaque. Conclusion: Regarding future policies for preventive strategies in schoolchildren, help with brushing at older ages can be recommended. Application of sealants can be encouraged, but further research is needed to confirm whether the presence of sealants improves oral cleanliness. Keywords: dental plaque, dietary habits, longitudinal analysis, oral hygiene habits

Objective: To compare the effectiveness of polymer burs (SmartPrep, SS White) and conventional carbide burs in removing dentin caries. Method and Materials: Thirty extracted permanent teeth were assigned to 2 groups according to the caries removal technique. One experienced clinician performed all excavation procedures, monitoring the caries removal by checking the hardness of the dentin with a dental explorer. The excavation working time was documented and stopped in each group when a leather-hard texture was reached. After the teeth were embedded and sectioned (400 µm), the caries in the remaining dentin was assessed using a caries detector. On microscope images of the samples, the mean stain depth of the remaining carious tissue per tooth was measured by AnalySIS computer software. Results: Mean carious surface areas differed minimally but not statistically significantly after use of polymer burs (31.5 mm2 ± 0.18) and carbide burs (38.1 mm2 ± 0.15). Mean carious surface staining depth was slightly smaller with carbide burs (0.26 mm ± 1.38) than with polymer burs (0.40 mm ± 1.15). The mean-quartile test for the total carious surface (P = .363) and the carious margin (P = .681) showed no statistically significant differences. Of the carbide bur-treated samples, 84.5% were caries free as opposed to 93.0% in the polymer bur group. The results also showed no significant difference between the mean working time of the polymer burs (5.11 minutes) and the carbide burs (4.99 minutes). Conclusion: Under these experimental conditions, polymer burs and tungsten carbide burs were similarly effective for caries removal. Keywords: carbide bur, caries removal, dentin caries excavation, dentin hardness, polymer bur

Severly impacted third molars have a high risk of developing a dentigerous cyst. Dental cysts in the maxilla can cause acute infection of the maxillary sinus that can involve the orbital cavity. Possible complications of infections of the orbital cavity are eyesight reduction, including blindness, and disseminated infections, including brain abscesses. This article reports on a 53-year-old male patient with diplopia caused by acute rectus inferior muscle palsy as symptoms of an empyema of the maxillary right sinus. An infected follicular cyst due to the impacted and displaced maxillary right third molar caused the empyema. An emergency trepanation with drainage of the right maxillary sinus was performed. Additionally, intravenous antibiotic therapy with penicillin G and metronidazole resulted in improvement. In a secondary surgical process 2 weeks later, the cyst and the third molar were removed. Complete recovery was noted. It is important to be familiar with clinical diagnostics in cases of undefined pain of the teeth and jaws. Radiographic imaging is indicated in such cases. Disseminated odontogenic infections must be considered as the primary origin of pain and diplopia. Keywords: complication, computerized tomography, follicular cyst, odontogenic infection, orbital cellulitis, third molar

Objective: To evaluate the clinical results of final-year dental students' clinical performance after a practical computer-based course and training in the new Cerec 3 method. Method and Materials: Cerec 3D restorations (Sirona) were made and inserted in patients by 50 dental students. The students were in their final semester in the Department of Operative Dentistry. Before treatment of the patients began, the students had undergone computer-based Cerec 3D training. The training included lessons comprising the whole Cerec procedure from planning to insertion of the restoration. Vital permanent premolars or molars requiring a 2- or 3-surface restoration were selected for the study. The evaluation started 1 week after luting. The inlays were examined in accordance with the US Public Health Service (USPHS) criteria at baseline and after 6, 12, and 24 months. Results: The 2-year survival rate of the restorations was estimated to be 93.3% according to Kaplan-Meier. No statistically significant changes were observed in color match, surface texture, and anatomic form. The decrease of pulpal hypersensitivity during the observation period was statistically significant (P < .05). Conclusion: Dental students are capable of delivering demanding clinical tasks after appropriate training. The introduction of CAD/CAM restorations to the dental curriculum resulted in high short-term success rates. Further investigations are required to evaluate the long-term success of those restorations. To achieve a clinically adequate performance, it is necessary to consider the basic rules and technology associated with ceramic restorations. Keywords: CAD/CAM, ceramic inlays, Cerec 3D, clinical study, computer-based course, dental education

Methamphetamine is not a new drug. It has a long and storied history of legitimate clinical use and recreational abuse. Unfortunately, abuse of methamphetamine is increasing with alarming frequency in the United States and leads to appalling destruction of dentition. The pathognomonic effects of methamphetamine abuse on teeth have led to the term "meth mouth." This term, while descriptive of the clinical appearance of patients, is a misnomer. A review of available information on methamphetamine abuse is presented and discussed. A clinical case is documented to help clinicians recognize and manage patients who may be abusing methamphetamines. Keywords: crystal meth, dental caries, dentistry, drug abuse, local anesthesia, meth mouth, methamphetamine

Objective: Biofilm accumulation on provisional restorations may affect the surrounding tissues' integrity. The purpose of this study was to test in vivo biofilm formation on polymethyl methacrylate (PMMA) self-cured acrylic resin provisional crowns. Method and Materials: Three types of PMMA surfaces were tested: (1) polished, (2) polished and coated with bonding agent, and (3) polished and coated with light-cured liquid polish. After 12 hours in the oral cavity, the crown was removed and examined by confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM). Results: Biofilm, 250 µm thick, was observed with CLSM on the polished acrylic surface. Significantly less bacterial accumulation was observed on the crowns coated with bonding agent, whereas no biofilm was observed on the crowns coated with liquid polish (P < .001). SEM examination confirmed these findings. Conclusions: Bonding resin or liquid polish coatings significantly reduce early biofilm formation, which in turn might affect the overall plaque accumulation on provisional restorations. Keywords: biofilm adhesion, bonding resin, liquid polish, polymethyl methacrylate, provisional crown

This article reports a case of retrieval of an ectopic molar medial to the coronoid process of the mandible that caused chronic discharging of a sinus into the mouth and recurrent facial swelling. Possible origin of the tooth and surgical approaches are discussed. Keywords: coronoid process, ectopic molar

Objective: To evaluate the efficacy of 1% ropivacaine for topical anesthesia in dentistry. Method and Materials: Thirty healthy volunteers randomly (blind crossover) received the following treatments: 20 mg of 1% ropivacaine gel (ropivacaine-20), 60 mg of 1% ropivacaine gel (ropivacaine-60), 20 mg of the eutectic mixture of local anesthetics 2.5% lidocaine and 2.5% prilocaine (EMLA cream, AstraZeneca; EMLA-20), 60 mg of EMLA (EMLA-60), 20 mg of 20% benzocaine gel (Benzotop, DFL; benzocaine-20), and 60 mg of 20% benzocaine gel (benzocaine-60), applied on the maxillary buccal fold of the right canine at different sessions. Pain was assessed by visual analog scale (VAS) and 11-point box scale (BS-11) after the insertion of 30-gauge needles. Soft tissue anesthesia was measured by pinprick test. Data were analyzed by Friedman and Pearson correlation tests. Results: All the topical anesthetics evaluated showed similar performance in relation to the pain perceived after needle insertion (P > .05), and there were no significant differences among groups considering VAS or BS-11 (P = .177 and P = .179, respectively). The duration of soft tissue anesthesia was not statistically significantly different for ropivacaine-20, EMLA-20, benzocaine-20, ropivacaine-60, EMLA-60, and benzocaine-60, but EMLA-60 showed significantly longer duration than the other agents (P < .05). Conclusion: All topical anesthetics were similar in reducing pain to needle insertion. EMLA-60 promoted longer duration of soft tissue anesthesia. Keywords: benzocaine, eutectic mixture of lidocaine and prilocaine, local anesthesia, oral mucosa, ropivacaine, topical anesthesia, topical anesthetic

The case of a maxillary third molar displaced into the infratemporal fossa, with difficulty in localization due to the synchronous creation of oroantral communication, is described in this article. The patient was referred to the oral and maxillofacial department and underwent successful surgical treatment through an intraoral access. The causes of tooth displacement into the infratemporal fossa, the aid of a computerized tomography (CT) scan in tooth localization, and the difficulty in treating this complication, particularly when the tooth migrates toward the base of the skull, are emphasized. Prevention of maxillary third molar displacement into the infratemporal fossa predominates over removal and is achieved by adequate flap design, correct extraction technique, and a distal retractor during surgical extraction. In the case of displacement, no effort to retrieve the tooth is recommended because of the risk of hemorrhage, neurologic injury, and further displacement of the tooth. The patient should be treated with antibiotics and referred to an oral and maxillofacial department. Keywords: accidental displacement, impacted tooth, infratemporal fossa, maxillary third molar, molar retrieval, tooth displacement

Objective: To investigate the chromatic changes of 3 porcelains after firing on titanium. Method and Materials: Thirty-six veneer crowns were obtained by firing 3 different porcelains to titanium: Ti22 (Noritake), Triceram (Esprident), and Vitatitankeramik (Vita). A single shade was used for each porcelain. Besides the titanium-porcelain specimens, 3 titanium-free controls (one for each porcelain) were obtained. A spectrophotometer was used to measure the color of porcelain facings of the veneer crowns and the porcelain controls. Once the chromatic digital values were recorded, the color differences between the titanium-porcelain samples and the corresponding porcelain controls were computed. The results were statistically analyzed. Results: The least chromatic difference was observed for Ti22 porcelain, and the greatest difference for Triceram porcelain. Regarding the direction of the chromatic alteration after firing on titanium, very significant differences were found between the porcelains. Conclusion: Perceivable differences were found between the shade of the porcelain fired to titanium and that of the same porcelain fired alone. No significant differences were found between the 3 porcelains regarding the total chromatic modification. Keywords: chromatic modification, color, porcelain, spectrophotometer, titanium, veneer

Objective: To compare the effect of endodontic access cavity location - labial versus palatal - on the resistance to fracture of maxillary incisors. Method and Materials: Sixty intact human maxillary incisors were selected: 20 pairs of central incisors and 10 pairs of lateral incisors. From each pair, 1 tooth was randomly selected to receive a palatal access cavity; the other tooth of the same pair received a labial access cavity. The teeth were divided into 4 test groups: group 1, central incisors with labial access; group 2, central incisors with palatal access; group 3, lateral incisors with labial access; and group 4, lateral incisors with palatal access. A lateral condensation technique was used to fill the canals with gutta-percha cones and AH-26 (Dentsply DeTrey). The access cavities were restored with hybrid resin composite. Specimens were mounted in a jig that allowed loading at the center of the palatal surface of the tooth, over the cingulum, at an angle of 130 degrees to the long axis of the tooth. Continuous compressive force at a crosshead speed of 2 mm/min was applied by an Instron universal testing machine. Load at fracture and mode of failure were recorded. Multiple analysis of variance (MANOVA) with repeated measures was used to statistically compare differences between groups at a significance of 5%. Results: Mean failure loads for the 4 test groups were as follows: 894 N (group 1), 821 N (group 2), 774 N (group 3), and 705 N (group 4). No significant difference in failure load values was found among all tested groups (F = 0.5; P > .05). The mode of failure in all groups was an oblique radicular fracture, either at the level of the cementoenamel junction in 40% to 45% or at the root level in 55% to 60% of the teeth. Conclusion: Different endodontic accesses-labial or palatal-did not affect the failure resistance of maxillary incisors under simulated occlusal load. Keywords: endodontic access, maxillary incisors, resistance to fracture

Objectives: To evaluate the effect of the surface preparation of a gold cylinder on the failure probability of highly filled all-composite restorations used as implant-supported prostheses, and to determine the effect of the location of load application. Method and Materials: Gold cylinders (Nobel Biocare) were prepared with 1 of 4 different surface preparations (n = 20 per surface treatment), and then an indirect resin composite (Targis, Ivoclar Vivadent) was applied. The 4 surface treatment conditions were (1) untreated (prep 1); (2) airborne-particle abraded with 50-µm alumina (prep 2); (3) airborne-particle abraded with 50-µm alumina followed by application of a metal conditioner (Alloy Primer, J. Morita) (prep 3); and (4) airborne-particle abraded with 50-µm alumina followed by application of the bonding primer for the indirect resin system (Targis Link) (prep 4). A compressive load was applied vertically at 1 mm and 2 mm from the access cavity on the occlusal surface until the restorations failed. Results: The prep 4 specimens had the highest fracture resistance. The fracture resistance at the 1-mm location was significantly higher than that at the 2-mm location. The failure load of the all-composite restorations with any of the surface preparations was lower than that of the resin-veneered restorations used as controls. Conclusion: The prep 4 conditions decreased the probability of fracture of the highly filled all-indirect resin composite restorations. Eccentric loading of the all-composite restorations should be minimized in light of the higher probability of failure associated with such a loading condition. Keywords: access cavity, all-composite restoration, failure, gold cylinder, implant-supported prosthesis, surface preparation

Objective: To evaluate the relationship between dental behavior, dental anxiety, and personality attachment traits among a healthy young adult population. Method and Materials: The study population consisted of 450 young adults (18 to 19 years old) who arrived for dental screening before military service. The survey was based on a questionnaire about dental behavior (ie, dental treatments and follow-up frequency, last dental visit, etc) as well as the Corah Dental Anxiety Scale (DAS) questionnaire, and the Self-Report Measurement of Adult Attachment (SRAA) questionnaire used to rate 3 adult attachment styles (secure, anxious, and avoidant). Results: The questionnaire was completed by 429 participants (95.3% response rate), in which 131 (30.5%) reported regular visits to their dental clinician and 61 (14.2%) did not visit a dental clinic at all. A total of 287 participants (66.9%) reported their last dental visit to be during the previous 2 years before the study, and 49 (11.4%) reported no visit to a dental office during the previous 5 years. DAS score ranged from 4 to 20 (mean 8.5 ± 3.3). High levels of dental anxiety, as indicated by DAS scores, correlated with less frequent dental visits, as well as with no visit to a dental clinic over the past few years. Participants who scored high on avoidant attachment were more likely to report occasional or no dental visits (P = .03). High DAS scores were more frequent among anxiously attached persons (P < .001) and among participants who scored high on attachment avoidance (P = .0013). Conclusions: Physiologic factors could have an impact on the patient's response. Patients, particularly anxious and avoidant attached ones, tend to visit the dental clinic less frequently. Keywords: anxiety, avoidance, Bowlby, dental fear, psychologic attachment, psychologic evaluation

Objective: To analyze the clinical behavior of 2 pit and fissure sealants through clinical/computerized evaluation. Method and Materials: Occlusal sealants were placed on maxillary and mandibular first and second premolars according to a split-mouth design. All premolars were sealed with either Concise (3M Espe) or Prisma Shield (Caulk/Dentsply) sealant agents. A hematoxylin-based staining solution was applied on the occlusal surface 7 days, 18 months, 36 months, and 11 years after occlusal sealing to allow checking of the sealant material on the surface. At each analysis time all occlusal surfaces were photographed, and the photographs corresponding to each time period were analyzed with SigmaScan 4.0 Software. The alterations of the sealed area of each sealant were analyzed with the software and recorded. Next, the measurements of the areas were tabulated and analyzed according to each period. Analysis of variance (ANOVA), with parts subdivided into time, and the t test, with a significance level of 5%, were used. Results: The greatest sealed area was maintained by the sealant Concise. However, over the course of 11 years, all sealants began to show the same level of alteration in sealed area. Conclusion: The sealing materials showed alteration in sealed area over time, but they were efficient in controlling caries lesion formation on premolar pits and fissures. Keywords: clinical/computerized analysis, measurement of sealant surface area, sealant

Self-injurious behavior is deliberate harm to the body that may lead to factitious oral injuries. Management of patients with self-inflicted injury continues to be a challenge for the dental profession. The purpose of this article is to review clinical findings in a patient who presented with severe, painful gingival recession in the primary dentition. A case report of an 8-year-old girl with mental retardation is presented. The periodontal examination showed bilateral gingival recession of the mandibular canines and the mandibular first and second molars so severe that it was possible to clinically observe the exposed roots. The diagnosis of self-inflicted gingival lesions and self-injurious behavior was established. Although the lesions are no longer present, the self-injurious behavior persists. Psychologic support was suggested, and an oral removable appliance was fitted. Keywords: factitious injury etiology, gingival injuries, gingival recession, oral self-mutilation, self-inflicted lesions, self-injurious behavior

Objective: To assess the influence of dental bleaching on the susceptibility of developing carieslike lesions. Method and Materials: Enamel slabs obtained from recently extracted human third molars were submitted to different bleaching techniques: at-home, with 10% and 16% carbamide peroxide (G1 and G2, respectively; Whiteness Perfect); and in-office, with 37% carbamide peroxide (G3; Whiteness Super) and 35% hydrogen peroxide (G4; Whiteness HP), activated by light-emitting diode and laser. The control groups G5 and G6 were not bleached. Afterward, all specimens, with the exception of G6, were exposed to a highly cariogenic challenge by means of pH cycling. G6 served as the control for the artificial caries development methodology. Assessment of the enamel carieslike lesions was made visually by 3 independent examiners, who attributed scores representing the severity of white spot lesions (0 to 3). Statistical analysis was performed with the Kruskal-Wallis (P ¡Ü .001) and multiple paired comparison tests. Results: Interrater reliability was expressed in a range of 0.70 to 0.82 kappa values. The median scores per group were as follows: G1 and G2 = 1; G3, G4, and G5 = 2; and G6 = 0. Conclusion: Home bleaching reduced the susceptibility to dental caries, while in-office bleaching did not influence the development of caries lesions. Keywords: demineralization, dental caries, enamel, in vitro, remineralization, tooth bleaching

Objective: Panoramic radiographs often are the first method used to screen edentulous patients before complete denture therapy. However, routine radiographic examination of edentulous patients is being questioned because of the cumulative effects and cost of radiation exposure. The purpose of this study was to determine the frequency and location of significant radiographic findings in edentulous jaws. Method and Materials: Panoramic radiographs from 338 patients were included in the survey (183 men, 155 women; 676 edentulous arches). The radiographs were evaluated by 1 oral radiology specialist for the following clinically significant radiographic findings: retained root fragments, impacted teeth, radiolucencies associated with cysts, radiopacities associated with localized sclerotic bone formation, location of the mental foramen on the crest, and location of the maxillary sinus close to the crest of the ridge. The data were analyzed using descriptive statistics. Results: Radiographic findings were found in 47.6% (56.5% women, 43.5% men) of the edentulous patients. Fifty-two subjects (29 women, 23 men) had 67 submucosal or intrabony root remains, 50 of which were located in the maxilla. The most frequent finding was retained root fragment, followed by radiopacities. Impacted teeth were found in 11 women and 10 men. In 15 patients the mental foramen was situated at the top of the residual ridge. Of these patients, 13 were women and 2 were men. In 29 patients (14 women, 15 men) the maxillary sinus was close to the crest of the ridge. Six patients (3 women, 3 men) had a bilateral maxillary sinus close to the crest of the ridge. The other 23 patients had a unilateral maxillary sinus close to the crest of the ridge, and except for in 2 men, all were in the left side of the maxilla. Conclusion: Routine panoramic examination of the jaws is necessary to detect impacted teeth, retained root fragments, and other radiographic findings that may require treatment before construction of complete dentures. Keywords: complete denture, edentulism, panoramic radiograph, radiographic evaluation

Objective: To evaluate coronal leakage and apical material extrusion of 3 obturation techniques. Method and Materials: The coronal part of 60 freshly extracted human maxillary central incisors was removed, leaving roots 10 mm in length. After instrumentation by hand K-files and smear layer removal, the 60 roots were divided randomly into 3 groups. The roots of each group were obturated using different obturation techniques. The obturation techniques tested were cold lateral condensation, System B, and Thermafil. Leakage measurements were accomplished using fluid filtration methodology. Filling material extrusion was recorded using a yes or no statement. Results were subjected to statistical analysis using chi-square tests. Results: Fluid filtration results revealed no significant differences among the 3 techniques tested 48 hours after obturation (P > .05). Thermafil tended to extrude significantly more material beyond the apex (P < .05). Conclusions: The 3 obturation techniques are equally effective at sealing the root canals. Thermafil's tendency for slight material extrusion should be considered when obturating canals with insufficient apical constriction. Keywords: cold lateral condensation, leakage, obturation, System B, Thermafil

Objective: To investigate corrosion in dental amalgam and evaluate the effects of composition and long-term aging on the alloy's corrosion behavior. Method and Materials: A sample of high-copper and low-copper formulations was employed. Corrosion tests were performed using a 3-electrode polarization cell. Anodic polarization curves were drawn, and the potential and the current density corresponding to the first anodic peak were registered. Scanning electron microscopy was performed, and the different metallurgical phases of the alloy's microstructure were examined and analyzed chemically using an energy-dispersive x-ray technique. The amalgams' corrosion behavior was evaluated at 1 week and after aging in a simulated oral environment for 6 months, 1 year, and 2 years. Data were analyzed using analysis of variance (ANOVA)/Scheffé post hoc test at a .05 significance level. Results: The potential values recorded by the high-copper amalgam were higher (P < .05) than those scored by the low-copper alloy. This was attributed to the presence of a tin-mercury, g2, phase in larger quantities in the low-copper amalgam than in the high-copper alloy. For both formulations the potentials increased significantly (P < .05) by about 70 mV after 2 years. This was ascribed to the gradual elimination of the corrosion-susceptible g2 phase and formation of a tin-copper, h, phase, particularly in the high-copper amalgam. Conclusion: High-copper amalgam exhibited better resistance to corrosion than the low-copper alloy. Aging in a simulated oral environment improved corrosion behavior for both high- and low-copper amalgams. Keywords: aging, anodic polarization, corrosion, high-copper amalgam, tin-copper (h) phase, tin-mercury (g2) phase

Objective: The aim of this investigation was to evaluate the cervical adaptation of metal crowns under several conditions, namely (1) variations in the cervical finish line of the preparation, (2) application of internal relief inside the crowns, and (3) cementation using different luting materials. Method and Materials: One hundred eighty stainless-steel master dies were prepared simulating full crown preparations: 60 in chamfer (CH), 60 in 135-degree shoulder (OB), and 60 in rounded shoulder (OR). The finish lines were machined at approximate dimensions of a molar tooth preparation (height: 5.5 mm; cervical diameter: 8 mm; occlusal diameter: 6.4 mm; taper degree: 6; and cervical finish line width: 0.8 mm). One hundred eighty corresponding copings with the same finish lines were fabricated. A 30-µm internal relief was machined 0.5 mm above the cervical finish line in 90 of these copings. The fit of the die and the coping was measured from all specimens (L0) prior to cementation using an optical microscope. After manipulation of the 3 types of cements (zinc phosphate, glass-ionomer, and resin cement), the coping was luted on the corresponding standard master die under 5-kgf loading for 4 minutes. Vertical discrepancy was again measured (L1), and the difference between L1 and L0 indicated the cervical adaptation. Results: Significant influence of the finish line, cement type, and internal relief was observed on the cervical adaptation (P < .001). The CH type of cervical finish line resulted in the best cervical adaptation of the metal crowns regardless of the cement type either with or without internal relief (36.6 ± 3 to 100.8 ± 4 µm) (3-way analysis of variance and Tukey's test, a = .05). The use of glass-ionomer cement resulted in the least cervical discrepancy (36.6 ± 3 to 115 ± 4 µm) than those of other cements (45.2 ± 4 to 130.3 ± 2 µm) in all conditions. Conclusion: The best cervical adaptation was achieved with the chamfer type of finish line. The internal relief improved the marginal adaptation significantly, and the glass-ionomer cement led to the best cervical adaptation, followed by zinc phosphate and resin cement. Keywords: cementation, finish line, glass-ionomer cement, marginal adaptation, Panavia, prosthodontics, resin cement, zinc phosphate cement

Objective: To evaluate the effect of thermocycling on microleakage of cervical cavities restored with hybrid and flowable resin composites polymerized with 3 different light-emitting diode (LED) curing techniques. Method and Materials: A total of 120 wedge-shaped cervical cavities were prepared on the buccal surfaces of human molars, restored with hybrid resin composite (Z250, 3M Espe) or with flowable resin composite (Filtek Flow, 3M Espe), and cured with either an LED standard light, an LED high-intensity light, or an LED exponential mode, which is a kind of soft-start curing method. The teeth in each group were divided randomly into 2 subgroups: (1) thermocycling for 1,000 cycles at 5°C and 55°C with a dwell time of 60 seconds, and (2) no thermocycling treatment. All teeth were immersed in 0.5% basic fuchsin dye solution for 24 hours. The teeth then were longitudinally sectioned and scored on a 0 to 3 scale at the enamel and dentin margins. Results: Nonparametric statistical analysis of the results showed a significant difference in microleakage between the nonthermocycled and thermocycled specimens, except for specimens cured with soft-start polymerization. Conclusion: The soft-start polymerization technique with LED light was not affected by thermocycling regimens. Keywords: curing methods, LED, microleakage, resin composite, thermocycling