Quantitative and Qualitative Evaluation of Enamel Erosion Following Air Abrasion with Bioactive Glass 45S5.

PURPOSE: To evaluate the effect of pre-treatment air abrasion of surfaces using bioactive glass 45S5 on the progression of erosion in bovine enamel induced by a common soft drink. MATERIALS AND METHODS: Twelve intact bovine incisors were selected and 24 enamel samples were prepared and randomly assigned to two groups (n = 12): 1. control group, no anti-erosive treatment; 2. experimental group: samples were air abraded with bioglass 45S5 before the erosive challenge. The enamel samples were submitted to erosive cycling using a common soft drink. Enamel surface loss was evaluated using optical profilometry; surface microhardness and roughness changes were determined using Vickers method and Vertical Scanning Interferometry, respectively. In addition, SEM observations and EDS analysis were performed to detect any alterations in surface morphology and mineral content. The data were statistically analysed using one-way ANOVA and Tukey's post-hoc test at a significance level of α = 0.05. RESULTS: The experimental group exhibited less (18.7%) surface loss than did the control group (p < 0.05), while also presenting a statistically significantly smaller decrease in surface microhardness compared to the control group after erosive cycling (p < 0.05). However, neither group showed a statistically significant change in surface roughness (p > 0.05). After the treatments, changes in surface morphology and mineral content of enamel were observed. CONCLUSIONS: Surface pre-treatment using air abrasion bioglass 45S5 may help prevent enamel erosion induced by excessive consumption of soft drinks. Further clinical trials are needed to confirm the effectiveness of this method and its clinical significance.

Evaluation of the Surface Characteristics of Dental CAD/CAM Materials after Different Surface Treatments.

Computer-aided design/computer-aided manufacturing (CAD/CAM) technology was developed to ensure the sufficient strength of tooth restorations, to improve esthetic restorations with a natural appearance and to make the techniques easier, faster and more accurate. In the view of the limited research on the surface treatments of the CAD/CAM materials and the need to evaluate the ideal surface characteristics of a material to achieve the best adhesion to tooth tissues, this study aimed to investigate the surface roughness and morphology of four different CAD/CAM materials using four different surface treatments. The CAD/CAM materials used in this study were three composites (Shofu Block HC, Lava Ultimate and Brilliant Crios) and a hybrid ceramic (Enamic). The surface of the specimens of each material received one of the following treatments: no surface treatment, sandblasting with 29 µm Al2O3 particles, 9% hydrofluoric acid etching and silane application, and the tribochemical method using CoJet System. Surface roughness was evaluated using optical profilometry, and surface morphology was observed by means of scanning electron microscopy. All surface treatments resulted in higher surface roughness values compared to the control group. Different treatments affected the surface properties of the materials, presumably due to discrepancies in their composition and structure.

Endocrown restorations for extensively damaged posterior teeth: clinical performance of three cases.

The restoration of endodontically treated teeth (ETT) with more than one cusp missing and thin remaining walls is challenging for the general practitioner. The use of posts combined with full coverage restorations is a well-established approach, yet not following the minimal invasive principles of adhesive dentistry. Endocrowns are indirect monoblock restorations that use the pulp chamber of the ETT for retention. In this study the fabrication of 4 endocrowns and their clinical performance will be discussed. Two clinical cases include computer-aided design/computer-aided manufacturing manufactured molar endocrowns (one feldspathic ceramic and one hybrid composite-ceramic restoration) and the other two are dental laboratory manufactured resin composite premolar endocrown restorations. The modified United States Public Health Service criteria were used to assess the clinical behavior of the restorations at different follow up periods. Endocrown restorations present a satisfactory clinical alternative, either by the use of resin composite or glass ceramic and hybrid materials. Specific guidelines with minimal alterations should be followed for an endocrown restoration to be successful. Due to limited evidence regarding the long term evaluation of this restorative technique, a careful selection of cases should be applied.

Spectrophotometric analysis of the effectiveness of a novel in-office laser-assisted tooth bleaching method using Er,Cr:YSGG laser.

The purpose of this in vitro study was to compare the effectiveness of a novel Er,Cr:YSGG laser-assisted in-office tooth bleaching method with a conventional method by spectrophotometric analysis of the tooth color change. Furthermore, the influence of the application time of the bleaching gel on the effectiveness of the methods and the maintenance of the results 7 days and 1 month after the treatments were also evaluated. Twenty-four bovine incisors were stained and randomly distributed into four groups. Group 1 specimens received an in-office bleaching treatment with 35% H2O2 for 2 × 15 min. Group 2 specimens received the same treatment but with extended application time (2 × 20 min). In Group 3, the same in-office bleaching procedure (2 × 15 min) was carried out as that in Group 1, using Er,Cr:YSGG laser irradiation for 2 × 15 s on each specimen to catalyze the reaction of H2O2 breakdown. Group 4 specimens received the same bleaching treatment as Group 3 but with extended application time (2 × 20 min). Er,Cr:YSGG laser-assisted tooth bleaching treatment is more effective than the conventional treatment regarding color change of the teeth. Application time of the bleaching agent may influence the effectiveness of the methods. The color change of the tested treatments decreases after 7 days and 1 month. The clinical relevance of this study is that this novel laser-assisted bleaching treatment may be more advantageous in color change and application time compared to the conventional bleaching treatment.

Comparative in vitro evaluation of CAD/CAM vs conventional provisional crowns.

OBJECTIVE: This study compared the marginal gap, internal fit, fracture strength, and mode of fracture of CAD/CAM provisional crowns with that of direct provisional crowns. MATERIAL AND METHODS: An upper right first premolar phantom tooth was prepared for full ceramic crown following tooth preparation guidelines. The materials tested were: VITA CAD-Temp®, Polyetheretherketone "PEEK", Telio CAD-Temp, and Protemp™4 (control group). The crowns were divided into four groups (n=10), Group1: VITA CAD-Temp®, Group 2: PEEK, Group 3: Telio CAD-Temp, and Group 4: Protemp™4. Each crown was investigated for marginal and internal fit, fracture strength, and mode of fracture. Statistical analysis was performed using GraphPad Prism software version 6.0. RESULTS: The average marginal gap was: VITA CAD-Temp® 60.61 (±9.99) µm, PEEK 46.75 (±8.26) µm, Telio CAD-Temp 56.10 (±5.65) µm, and Protemp™4 193.07(±35.96) µm (P<0.001). The average internal fit was: VITA CAD-Temp® 124.94 (±22.96) µm, PEEK 113.14 (±23.55) µm, Telio CAD-Temp 110.95 (±11.64) µm, and Protemp™4 143.48(±26.74) µm. The average fracture strength was: VITA CAD-Temp® 361.01 (±21.61) N, PEEK 802.23 (±111.29) N, Telio CAD-Temp 719.24 (±95.17) N, and Protemp™4 416.40 (±69.14) N. One-way ANOVA test showed a statistically significant difference for marginal gap, internal gap, and fracture strength between all groups (p<0.001). However, the mode of fracture showed no differences between the groups (p>0.05). CONCLUSIONS: CAD/CAM fabricated provisional crowns demonstrated superior fit and better strength than direct provisional crowns.

Comparative in vitro evaluation of CAD/CAM vs conventional provisional crowns

ABSTRACT Objective This study compared the marginal gap, internal fit, fracture strength, and mode of fracture of CAD/CAM provisional crowns with that of direct provisional crowns. Material and Methods An upper right first premolar phantom tooth was prepared for full ceramic crown following tooth preparation guidelines. The materials tested were: VITA CAD-Temp®, Polyetheretherketone “PEEK”, Telio CAD-Temp, and Protemp™4 (control group). The crowns were divided into four groups (n=10), Group1: VITA CAD-Temp®, Group 2: PEEK, Group 3: Telio CAD-Temp, and Group 4: Protemp™4. Each crown was investigated for marginal and internal fit, fracture strength, and mode of fracture. Statistical analysis was performed using GraphPad Prism software version 6.0. Results The average marginal gap was: VITA CAD-Temp® 60.61 (±9.99) µm, PEEK 46.75 (±8.26) µm, Telio CAD-Temp 56.10 (±5.65) µm, and Protemp™4 193.07(±35.96) µm (P<0.001). The average internal fit was: VITA CAD-Temp® 124.94 (±22.96) µm, PEEK 113.14 (±23.55) µm, Telio CAD-Temp 110.95 (±11.64) µm, and Protemp™4 143.48(±26.74) µm. The average fracture strength was: VITA CAD-Temp® 361.01 (±21.61) N, PEEK 802.23 (±111.29) N, Telio CAD-Temp 719.24 (±95.17) N, and Protemp™4 416.40 (±69.14) N. One-way ANOVA test showed a statistically significant difference for marginal gap, internal gap, and fracture strength between all groups (p<0.001). However, the mode of fracture showed no differences between the groups (p>0.05). Conclusions CAD/CAM fabricated provisional crowns demonstrated superior fit and better strength than direct provisional crowns.

Effect of Er,Cr:YSGG laser on the surface of composite restoratives during in-office tooth bleaching.

The aim of this in vitro study was to investigate the effect of Er,Cr:YSGG laser on the surface roughness and microhardness of various composite restoratives during in-office tooth bleaching. Five highly viscous composite restoratives and three flowable composite restoratives were investigated. Thirty cylindrical specimens of each material were made using Teflon molds. The specimens of each composite were randomly divided into three groups (n = 10). Group 1 specimens did not receive bleaching treatment, group 2 received a conventional in-office bleaching treatment, and group 3 received a laser-assisted in-office bleaching treatment using an Er,Cr:YSGG laser. Two-way ANOVA was used to determine significant interactions between materials and bleaching methods. One-way ANOVA and Tukey's post hoc test were used to compare the mean surface microhardness and roughness between materials for each treatment group (a = 0.05). Τhere were no significant differences in surface microhardness between the two bleached experimental groups for all the tested composites (p > 0.05). The reduction of surface microhardness after bleaching procedures ranged from 0.72 to 16.93 % for the specimens received conventional treatment and from 1.30 to 11.51 % for those received laser-assisted treatment. Moreover, there were no significant differences in Ra values between the experimental groups (p > 0.05) in all cases. The increase of surface roughness after the bleaching treatments was negligible and was between 0.43 and 4.78 %. The use of Er,Cr:YSGG laser during in-office tooth bleaching treatment did not affect the surface microhardness and roughness of the tested composite restorative materials.

Accidental ingestion of an air-water syringe tip during routine dental treatment: a case report.

Accidental ingestion of instruments or their components is a possible complication of dental treatment. Although in many cases the foreign object can pass through the gastrointestinal tract without any need for surgical intervention to retrieve it, sometimes such incidents can be life-threatening. This paper reports a case of accidental ingestion of an air-water syringe tip during routine dental treatment for which endoscopic retrieval was required. The present case highlights the need for dental professionals to be aware of the fact that dental equipment comprising multiple components may be associated with a risk of accidental detachment of a component and its ingestion or aspiration by a patient receiving treatment.

Effect of extraction media and storage time on the elution of monomers from four contemporary resin composite materials.

INTRODUCTION: The purpose of this study was to examine the effect of different extraction media, including culture media, as well as storage times on the elution of monomers from modern dental composites. MATERIALS AND METHODS: FOUR CONTEMPORARY COMPOSITE MATERIALS WERE TESTED: (a) Clearfil Majesty Esthetic (Kuraray), (b) Esthet X (DENTSPLY), (c) Filtek Silorane (3M ESPE), and (d) Admira (Voco). Forty-eight specimens were made. The specimens were stored in 1 ml of (a) artificial saliva, (b) Dulbecco's Modified Eagle Medium (DMEM), (c) DMEM plus 10% fetal bovine serum (FBS), and (d) ethanol 75%. The specimens were analyzed after 24 hours and after 1 week of storage. HPLC Liquid Chromatography was performed to analyze the extracted solutions. The statistical package SPSS 18 was used for the statistical analysis of the results. RESULTS: All the materials tested released monomers that were consistent with the base composition of their resin matrix. Bisphenol-A (BPA) was detected in Clearfil Esthetic and EsthetX when ethanol 75% was used for storage. TEGDMA was released at a faster rate compared to the other monomers with most of the monomer eluted in the first 24 hours. The effect of storage solution and storage time on the elution of the same monomers varied between materials. CONCLUSIONS: There was a significant effect of time, storage solution, and material on the elution of the detectable unbound monomers. Unbound monomers were detected in culture media, which may lead to false-negative results in cytotoxicity tests of resin composite materials. BPA was detected in two of the tested materials.

Fracture strength of minimally prepared all-ceramic CEREC crowns after simulating 5 years of service.

OBJECTIVES: To examine the strength and mode of fracture of traditionally and minimally prepared all-ceramic resin bonded CAD/CAM crowns after fatigue loading. METHODS: Thirty human maxillary molars were used and divided in three groups namely; traditional crown preparation group (I), minimal crown preparation group (II) and occlusal veneer preparation group (III). A leucite reinforced glass ceramic (IPS Empress CAD) was used for fabricating the crowns. The CEREC InEOS system (v3.10) was used for scanning, designing and milling. Five years of clinical service were simulated and the fracture strength of the crowns was measured. One-way ANOVA and Kruskal-Wallis test were used for data analysis (α=0.05). RESULTS: The mean fracture strength and SD in Group I was 1070N (±181) and in Group II 1110N (±222). One-way ANOVA analysis showed no statistically significant difference between the two groups (p>0.05). In Group III all restorations developed cracks during TCML and were not subjected to fracture loading. Three of the traditionally designed crowns (Group I) and 4 of the minimally designed crowns (Group II) developed surface cracks during TCML. SIGNIFICANCE: Minimal all-ceramic resin-bonded crowns can potentially form a viable restorative option as they demonstrated comparable strength to traditional all-ceramic crowns. However, this should be interpreted with caution as a number of crowns showed cracks after 5 years of simulated service. All the occlusal veneers developed cracks during simulation and further investigation is needed for this to be considered a viable option.

Temperature rise during photo-polymerization under ceramic restorations.

AIM: The aim of this study was to measure the temperature increase induced by various light-curing units during photo-polymerization beneath ceramic restorations. METHODS: Three light-curing units were used; a high intensity QTH unit Elipar 2500 and two LED units: Translux Power Blue and Excelled 1400. The 15 ceramic specimens (CEREC Blocks) used in this study were of 2.5 mm thickness, 5 mm wide and 6 mm long and made using a slow speed saw. Using the same slow speed saw the occlusal enamel portion of 15 mandibular third molars was removed and 15 dentin discs of 1 mm height were prepared. The thickness of the luting cement was delimited to 0.5 mm, using a Teflon mold and then brought into contact with the dentin disc. Light-curing time for all the groups was 20 sec. The temperature rise was measured placing underneath the dentin disc a K-type thermocouple wire connected to a data logger. Five measurements were carried out for each group. Statistical analysis was performed using ANOVA (a=0.05). RESULTS: The results indicated that there was a lower temperature rise induced from Translux Power Blue than from the other two light-curing units, which did not present statistically significant difference (p<0.05). However, temperature rise from the light-curing units used in this study is lower than 5.5°C, which is the limit of pulpal damage. CONCLUSIONS: Within the limitations of this study, although the type and characteristics of light-curing units may affect temperature rise under ceramic restorations, this influence is possibly not of clinical significance.

Evaluation of the marginal integrity of ceramic copings with different marginal angles using two different CAD/CAM systems.

OBJECTIVES: To investigate and compare the marginal integrity of ceramic copings constructed with the CEREC3 and the EVEREST system employing three different margin angle designs and explore to what extent these CAD/CAM machines can produce acute marginal angles creating restorations with acceptable margins. MATERIALS AND METHODS: Three brass models were prepared with a different marginal finish line, namely a 0° bevel (or 90° shoulder), a 30° bevel and a 60° bevel. Ten restorations were produced for each finishing line and CAD/CAM system, respectively. The copings were milled from lithium disilicate glass ceramic blocks (IPS e.max(®) CAD). An impression was taken for each model to fabricate a series of 10 replica dies for each marginal design. Quantitative analysis of the margins of each coping was performed using digital photography and image analysis software. The marginal integrity of the restorations was evaluated by detecting and measuring any signs of marginal chipping and the Chipping Factor (CF) was calculated. Statistical analysis was performed using Univariate Analysis of Variance and multiple comparisons (Tukey HSD). RESULTS: The average Chipping Factor (CF) of the CEREC copings was: 2.8% for the 0° bevel angle, 3.5% for the 30° bevel angle and 10% for the 60° bevel angle. For the EVEREST copings the average CF was: 0.6% for the 0° bevel angle, 3.2% for the 30° bevel angle and 2.0% for the 60° bevel angle. Univariate Analysis of Variance and multiple comparisons showed that there was a statistically significant difference in the quality of margins between the two systems for the 0° and 60° bevel finishing line. CONCLUSIONS: The results of this study indicated that the introduction of a marginal angle of the restoration increases the potential for marginal chipping. Different CAD/CAM systems which employ different milling processes produce restorations with different amount of marginal chipping, although this only became apparent for a marginal angle of a 60°.

A preliminary evaluation of the structural integrity and fracture mode of minimally prepared resin bonded CAD/CAM crowns.

PURPOSE: This study was a preliminary evaluation of two minimal preparation designs proposed for ceramic and composite resin bonded CAD/CAM crowns. It compared the structural integrity and fracture mode of teeth restored with traditionally and minimally prepared resin bonded CAD/CAM crowns fabricated from the same material hypothesizing that teeth restored with minimal resin bonded crowns would demonstrate the same fracture strength to teeth restored with traditional resin bonded crowns. MATERIALS AND METHODS: Forty intact maxillary molar teeth were used and divided in four groups. Two groups were prepared according to a traditional crown preparation design and two groups were prepared according to minimal preparation designs. A resin composite (Paradigm MZ100, 3M ESPE) and a leucite glass-ceramic (ProCAD, Ivoclar Vivadent) were used for the fabrication of the crowns using CEREC Scan. Crowns of ceramic were cemented using Variolink II (Ivoclar Vivadent) and crowns of composite with Rely X Unicem Aplicap (3M ESPE) and loaded until fracture. Load data was analysed using ANOVA comparing crowns of the same restorative material. The mode of fracture was also recorded and analysed (Kruskal-Wallis). RESULTS: For the composite system the mean fracture load and SD was 1682N (+/-315) for the traditional and 1751N (+/-338) for the minimal crowns. For the ceramic system the mean fracture load and SD was 1512N (+/-373) for the traditional and 1837 (+/-356) for the minimal crowns. No statistically significant difference was found between the two designs for each system. Nonparametric analysis (Kruskal-Wallis) of the fracture mode showed no statistical significant difference between designs for either material (p>.05). CONCLUSION: Within the limitations of this experimental design, it was found that minimally prepared resin bonded CEREC crowns demonstrated equal fracture resistance and mode of fracture to that of crowns bonded to traditionally prepared teeth.

Fracture strength of minimally prepared resin bonded CEREC inlays.

PURPOSE: This study compared the structural integrity and fracture mode of teeth restored with traditionally and minimally prepared resin-bonded CAD/CAM inlays fabricated from the same material. METHODS: Forty intact maxillary premolars were used and divided into four groups. Two groups were prepared according to a traditional inlay preparation design (2.0 mm occlusal reduction, a 1.5 mm wide proximal box and divergent walls) and two groups were prepared according to a newly proposed minimal preparation design (round shaped cavity with 1.0 mm occlusal reduction, a U-shaped proximal box 1.0 mm wide and parallel walls). Two restorative systems were tested: a composite system comprised of Paradigm MZ100 (3M ESPE) blocks and RelyX Unicem (3M ESPE) resin cement and a ceramic system comprised of ProCAD blocks (Ivoclar-Vivadent) and Variolink II (Ivoclar-Vivadent) resin cement. The inlays were cemented according to the manufacturers' instructions. Each specimen was loaded axially to its occlusal surface at a crosshead speed of 0.5 mm/minute in a universal testing machine until fracture. The fracture load data were analyzed using ANOVA, comparing inlays of the same restorative material. Also, the mode of fracture of the inlays was recorded and analyzed using a non-parametric test (Kruskal-Wallis). RESULTS: In the composite system case, the mean fracture load and SD were 1322 N (+/- 445) for the traditional inlays and 1511 N (+/- 395) for the minimal inlays, while in the ceramic system case, those values were 1135N (+/- 450) for the traditional inlays and 1761 N (+/- 494) for the minimal inlays. Statistical analysis of the results showed that there was no statistically significant difference between the two designs for the composite system, while for the ceramic system, the minimally prepared teeth showed higher mean fracture strength. Non-parametric analysis (Kruskal-Wallis) of the mode of fracture showed that there was no statistically significant difference between traditionally and minimally prepared inlays for both systems (p > .05). CONCLUSIONS: Under the conditions of this experimental study, only the ceramic inlays, when prepared with a minimal preparation design, demonstrated a higher fracture strength as compared to the traditionally prepared teeth. Use of the proposed minimal preparation design did not compromise the immediate post-operative structural integrity of teeth restored either with resin composite or ceramic inlays.

The incidental finding of a retained gunshot pellet.

An 80-year-old woman presented to the restorative department at the Charles Clifford Dental Hospital in Sheffield for a routine review of her dental health with no reported trauma, pain or complications relating to the oral environment. A routine periapical radiograph showed the presence of a foreign object in the right maxillary second premolar region. An unusual case is reported of a retained gunshot pellet lying in the upper buccal mucosa for 70 years without the patient experiencing any pathological signs or symptoms.

A blended learning course taught to different groups of learners in a dental school: follow-up evaluation.

This article reports the results of a follow-up study conducted to investigate students' perceptions about a blended learning health informatics course that combined online and traditional classroom instruction. The course is taught to five different groups of students at the School of Clinical Dentistry of the University of Sheffield each academic year: first-, third-, and fourth-year dental students, dental hygiene and therapy students, and postgraduate dental students. The goal of the study was to determine the impact of the modifications made to the course after the first year of implementation. To accomplish this goal, students' perceptions of this blended learning course were compared after the first and second implementations. The methodology used for this study was action research. The data were collected using three processes: questionnaires were used to collect contextual data from the students taking the course; a student-led, nominal group technique was used to collect group data from the participants; and a non-participant observer technique was used to record the context in which certain group and individual behaviors occurred. Depending on group assignment, between 41.5 and 91.5 percent of students believed that the blended-learning course had added to their skills. The online learning environment was perceived as a useful resource by 75 percent of students in four of the five student groups, but only 45 percent of the fourth-year dental students indicated it was a useful resource. The perceived lack of sufficient online support material was one of the main concerns of the students at the nominal group evaluation sessions. The non-participant observer technique identified different engagement levels among the student groups. Discernible differences were identified, with improvement in some areas and a decline in others compared to a previous evaluation. The change in the delivery method influenced the students' comprehension of the material negatively and the learning environment positively, but did not influence online collaboration among students.

Brittleness index of machinable dental materials and its relation to the marginal chipping factor.

OBJECTIVES: The machinability of a material can be measured with the calculation of its brittleness index (BI). It is possible that different materials with different BI could produce restorations with varied marginal integrity. The degree of marginal chipping of a milled restoration can be estimated by the calculation of the marginal chipping factor (CF). The aim of this study is to investigate any possible correlation between the BI of machinable dental materials and the CF of the final restorations. METHODS: The CEREC system was used to mill a wide range of materials used with that system; namely the Paradigm MZ100 (3M/ESPE), Vita Mark II (VITA), ProCAD (Ivoclar-Vivadent) and IPS e.max CAD (Ivoclar-Vivadent). A Vickers Hardness Tester was used for the calculation of BI, while for the calculation of CF the percentage of marginal chipping of crowns prepared with bevelled marginal angulations was estimated. RESULTS: The results of this study showed that Paradigm MZ100 had the lowest BI and CF, while IPS e.max CAD demonstrated the highest BI and CF. Vita Mark II and ProCAD had similar BI and CF and were lying between the above materials. Statistical analysis of the results showed that there is a perfect positive correlation between BI and CF for all the materials. CONCLUSIONS: The BI and CF could be both regarded as indicators of a material's machinability. Within the limitations of this study it was shown that as the BI increases so does the potential for marginal chipping, indicating that the BI of a material can be used as a predictor of the CF.

Evaluation of the marginal fit of three margin designs of resin composite crowns using CAD/CAM.

OBJECTIVES: To examine the marginal fit of resin composite crowns manufactured with the CEREC 3 system employing three different margin designs; bevel, chamfer and shoulder, by means of a replica technique and a luting agent. METHODS: Three master casts were fabricated from an impression of a typodont molar tooth and a full-coverage crown prepared with a marginal finish of a bevel, a chamfer and a shoulder. Each cast was replicated 10 times (n=10). Scanning of the replicas and crown designing was performed using the CEREC Scan system. The crowns were milled from Paradigm MZ100 composite resin blocks. The marginal fit of the crowns was evaluated with a replica technique (Aquasil LV, Dentsply), and with a resin composite cement (RelyX Unicem, Aplicap) and measured with a travelling microscope. Statistical analysis was performed using two-way ANOVA. RESULTS: For the replica technique the average marginal gaps recorded were: Bevel Group 105+/-34 microm, Chamfer Group 94+/-27 microm and Shoulder Group 91+/-22 microm. For the resin composite cement the average marginal gaps were: Bevel Group 102+/-28 microm, Chamfer Group 91+/-11 microm and Shoulder Group 77+/-8 microm. Two-way ANOVA analysis showed that there was no statistically significant difference between the three groups of finishing lines regardless of the cementation technique used. CONCLUSIONS: The marginal gap of resin composite crowns manufactured with the CEREC 3 system is within the range of clinical acceptance, regardless of the finishing line prepared or the cementation technique used.