The Treatment and Management of Oroantral Communications and Fistulas: A Systematic Review and Network Metanalysis.

OBJECTIVES: The aim of this work was to systematically review and carry out a statistical metanalysis to identify the best treatment for close oroantral communications and fistulas and to avoid the risk of recurrence. MATERIALS AND METHODS: An electronic search was conducted on the MEDLINE database (Pubmed), Scopus, and Google scholar using the following keywords: "oro antral communication (OAC)" OR "oro antral fistula (OAF)" OR "antro-oral communication" OR "communication between maxillary sinus and oral cavity" OR "oro-sinusal communication" OR "oro-sinusal fistula" OR "sinus communication" OR "sinus fistula" OR "antral communication" AND "treatment" OR "management" OR "surgical treatment" OR "surgical interventions". This work was performed in accordance with the guidelines of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses). After article screening, 9 RCTs (randomized controlled trials), comparing two or more techniques, were included in this review. RESULTS: A statistically significant difference was detected in favor of the buccal fat pad compared to the buccal advancement flap and palatal rotational flap. CONCLUSIONS: With the limitations of this study, the buccal fat pad showed the best results in terms of communication closure and reducing the risk of relapse.

Ozone and Laser Effects on Dentin Hypersensitivity Treatment: A Randomized Clinical Study.

INTRODUCTION: The aim of this study was to evaluate and compare the clinical efficacy of diode laser and ozone gas in the treatment of dentin hypersensitivity (DHS). METHODS: One hundred thirty-two teeth from 44 patients with moderate DHS were randomized into 3 groups according to a split-mouth design. In the diode laser group, the operator irradiated the superficial dentin exposed with an 808-nm wavelength and incremental power from 0.2 to 0.6 W with a 20-second interval. In the ozone gas group, the operator applied a high dose of ozone (32 g/m3) for 30 seconds using a silicon cup. In the placebo group, no therapy was applied. The dentin sensitivity level was evaluated upon enrollment (T0), immediately after treatment (T1), 3 months post-treatment (T2), and 6 months post-treatment (T3) with a cold air blast challenge and tactile stimuli. The pain severity was quantified according to the visual analogue scale. The Wilcoxon signed rank test was used to scrutinize potential statistical disparities among the treatments. Statistical significance was predetermined at P < .05. RESULTS: A significant decrease of DHS was observed in the ozone gas group and the `diode laser group immediately after treatment and after 3 and 6 months of the therapy. After 6 months from the therapy, the sensitivity values in the teeth treated with ozone gas remained statistically lower than those treated with diode lasers (P < .05). CONCLUSIONS: A laser diode and ozone gas are both efficient as dentin sensitivity treatment. Ozone maintains an invariable effectiveness after 6 months.

Low-Level Laser Therapy for the Treatment of Oral Mucositis Induced by Hematopoietic Stem Cell Transplantation: A Systematic Review with Meta-Analysis.

Oral mucositis is a common and debilitating side effect induced by stem cell transplantation that is experienced by cancer patients undergoing chemotherapy or radiation therapy. This condition involves inflammation and ulceration of the oral mucosa, leading to pain, difficulty with eating and speaking, and an increased risk of infections. Mucositis not only compromises the quality of life for cancer patients, but also affects treatment outcomes and may necessitate dose reductions or treatment delays. This scientific article provides a comprehensive overview of mucositis. The purpose of this literature review with a meta-analysis is to evaluate the efficacy of laser therapy in treating post-transplant mucositis. Materials and methods: A search of the literature from 3 May 2023 was carried out on three online databases, PubMed, Scopus, and Web of Science. Only studies that treated patients with laser therapy were considered; only studies with the placebo-treated control group were considered. Review Manager version 5.2.8 (Cochrane Collaboration) was used for the pooled analysis. We measured the std. mean difference between the two groups (laser and placebo). Results: There were 230 papers included in this review. Two hundred twenty-seven were excluded. Furthermore, a manual search was performed. After the search phase, three articles were considered in the study. The overall effect showed differences in the degree of mucositis in the laser-treated patients compared with the placebo group. The meta-analysis shows a reduction in the degree of mucositis in the patients treated with laser therapy (std. mean difference -1.34 [-1.98; -0.98]; C.I. 95%). Conclusions: The application of laser therapy results in decreased severity of oral mucositis from radiation and chemotherapy. Our study shows that the application of low-level laser therapy in the treatment of transplant mucositis has excellent efficacy in relieving the symptoms and severity of mucositis.

The socket shield technique and its complications, implant survival rate, and clinical outcomes: a systematic review.

PURPOSE: The aim of this systematic review was to evaluate the effectiveness of the socket shield technique (SST), an innovative surgical method introduced in 2010, for reducing buccal bone plate resorption. METHODS: The review was conducted following the PRISMA guidelines. Clinical studies conducted in humans and investigating the SST were searched on PubMed (MEDLINE), Embase, Web of Knowledge, and Google Scholar in November and December 2021. The implant survival rate, percentage of complications, and clinical parameters (marginal bone loss [MBL], pink esthetic score [PES], and buccal bone plate resorption [BBPR]) were analyzed using the collected data. RESULTS: The initial search resulted in 132 articles. After article screening, the full texts of 19 studies were read and 17 articles were finally included in the review. In total, 656 implants were installed with the SST. Nine of the 656 implants experienced failure, resulting in an implant survival rate of 98.6%. The percentage of complications was about 3.81%. The analysis of clinical parameters (MBL, PES, and BBPR), showed favorable results for the SST. The mean MBL in implants placed with the SST was 0.39±0.28 mm versus 1.00±0.55 mm in those placed without the SST. PES had a better outcome in the SST group, with an average of 12.08±1.18 versus 10.77±0.74. BBPR had more favorable results in implants placed with the SST (0.32±0.10 mm) than in implants placed with the standard technique (1.05±0.18 mm). CONCLUSIONS: The SST could be considered beneficial for preserving the buccal bone plate. However, since only 7 of the included studies were long-term randomized controlled trials comparing the SST with the standard implant placement technique, the conclusions drawn from this systematic review should be interpreted with caution. TRIAL REGISTRATION: PROSPERO Identifier: CRD42020180637.

Effect of Light-Sources and Thicknesses of Composite Onlays on Micro-Hardness of Luting Composites.

The aim of this study was to compare three different light-curing-units (LCUs) and determine their effectiveness in the adhesive cementation of indirect composite restorations when a light-curing resin cement is used. Two resin composites were selected: Enamel Plus HRI (Micerium) and AURA (SDI). Three thicknesses (3 mm, 4 mm and 5 mm) were produced and applied as overlays and underlays for each resin composite. A standardized composite layer was placed between underlay and overlay surfaces. Light curing of the resin-based luting composites was attained through the overlay filters using LCUs for different exposure times. All specimens were allocated to experimental groups according to the overlay thickness, curing unit and curing time. Vickers Hardness (VH) notches were carried out on each specimen. Data were statistically evaluated. The curing unit, curing time and overlay thickness were significant factors capable of influencing VH values. The results showed significantly decreased VH values with increasing specimen thickness (p < 0.05). Significant differences in VH values were found amongst the LCUs for the various exposure times (p < 0.05). According to the results, a time of cure shorter than 80 s (with a conventional quartz-tungsten-halogen LCU) or shorter than 40 s (with a high-power light-emitting diode (LED) LCU) is not recommended. The only subgroup achieving clinically acceptable VH values after a short 20 s curing time included the 3 mm-thick overlays made out of the AURA composite, when the high-power LED LCU unit was used (VH 51.0). Composite thickness has an intense effect on polymerization. In clinical practice, light-cured resin cements may result in insufficient polymerization for high thickness and inadequate times. High-intensity curing lights can attain the sufficient polymerization of resin cements through overlays in a significantly shorter time than conventional halogen light.

Microtensile Bond Strength of Etch-and-Rinse Adhesives in Different Hydroabrasion Conditionings.

The aim of the present study was to in vitro evaluate the effect of dentin conditioning with hydroabrasion on the microtensile bond strengths of three adhesive systems, compared to the standard etch-and-rinse technique. Sixty extracted human third molars were collected, and their midcoronal occlusal dentin was used for the microtensile bond strength test. Teeth were randomly assigned to three groups according to the adhesive system used: ExciTE F DSC, ENA Bond, and Scotchbond Universal. Specimens from each group were further divided into four subgroups: control specimens were treated with standard adhesive procedures; hydroabraded (HA) specimens were subjected to preventive hydroabrasion with three different intensity levels. After bonding procedures, composite crowns were incrementally built up. After thermocycling, specimens were subsequently sectioned into 1 × 1 mm sticks, and microtensile bond strengths were measured. Data were statistically analyzed. Failure mode analysis was performed. There were no significant differences in terms of bond strength between standard adhesion protocols and adhesion with HA preconditionings. On the other hand, the type of adhesive used had a significant effect on the tensile bond strength. Subgroups treated with hydroabrasion at higher intensity showed a slightly increased frequency of cohesive fractures. In conclusion, hydroabrasion can be used for dentin cavity preparation or finishing, since it does not seem to affect the bonding effectiveness.

Debonding and Clean-Up in Orthodontics: Evaluation of Different Techniques and Micro-Morphological Aspects of the Enamel Surface.

There is currently no consensus on the best way to remove adhesive remnants from teeth following debonding. The main objective of this study is to evaluate and compare the effectiveness of four adhesive resin removal (clean-up) techniques, performed with or without the use of an operative microscope. Forty human teeth were duplicated using an epoxy resin for impregnation. Brackets were bonded to teeth and debonded from teeth. Then, the samples were randomly divided into two equal groups-the naked eye group and the magnification group-and further subdivided into four equal subgroups, in order to compare the different techniques used for the clean-up. Each subgroup was formed of five natural teeth with the respective pre- and post-bonding replicas. Macro- and micro-analysis by means of a stereomicroscope and scanning electron microscopy evaluated, qualitatively and quantitatively, the adhesive remnant index and the damage index of the enamel. Overall, the magnification improved the removal of resins compared to the naked eye (p < 0.001), and the use of magnification constantly reduced resin residual and surface damage. Enamel damage and adhesive residual from the clean-up procedures represent an ascertained risk in orthodontics. The use of a magnification system improves the quality of debonding and clean-up techniques in a significant way.

Single tooth anesthesia versus conventional anesthesia: a cross-over study.

OBJECTIVES: The aim of the present study was to compare an electronic device, the Wand Injection System (Milestone Scientific Livingstone), with conventional anesthesia in terms of the following: pain sensation during anesthetic injection; effectiveness in achieving adequate anesthesia for a complete painless dental treatment; post-operative discomfort; and patient's anxiety toward dental treatment. MATERIALS AND METHODS: Eighty adults from 18 to 70 years were enrolled in this cross-over study. Each patient served as his/her own control being subject to two anesthesia techniques: conventional and Single Tooth Anesthesia (STA) performed with the Wand. A split-mouth design was adopted in which each tooth undergoing conservative restorative or endodontic treatment received anesthesia with both techniques at 1-week interval. Before anesthetic administration, the patients' anxiety levels were determined. Physiological parameteres were measured before, during, and after the two injection procedures, and the Visual Analogue Scale (VAS) was used to assess pain of injection, discomfort, and anesthetic efficacy. Differences in assessment of pain's injection, discomfort, anesthetic efficacy, vital parameters (heart rate, blood pressure, and oxygen saturation), and state anxiety levels were analyzed using Student's t test (p value < 0.001). RESULTS: The mean injection pain and post-operative discomfort ratings with Wand were lower than those with conventional syringe (p = 0.022 and p < 0.001, respectively). No differences were found in the assessment of anesthetic efficacy. Blood pressure and heart rate mean values were lower during the anesthesia performed with the Wand than with the conventional syringe (p < 0.001). The anxiety level was higher during the first appointment, independently from the device used for the injections. CONCLUSION: The STA technique resulted in lower pain, discomfort, and lower intensity of physiological parameters. CLINICAL RELEVANCE: Single Tooth Anesthesia could be an efficacious alternative to conventional procedures.

Protocol for a new concept of no-prep ultrathin ceramic veneers.

OBJECTIVES: No-prep veneers, although ideally considered the best option because of tooth structure maximum preservation, have been frequently criticized for some potential limitations including esthetic outcomes and periodontal complications. CLINICAL CONSIDERATIONS: A new protocol to optimize no-prep veneers restorations is presented. A key point of the proposed technique is to identify optimal margins' positions: margin is positioned in the point of maximum convexity of teeth, avoiding the over contouring of traditional no-prep veneers. CONCLUSION: The procedure can be appreciated for the marginal accuracy and the resulting aesthetic stability. The case reports show that properly managed no-prep veneers can have biologically healthy and aesthetically pleasant tooth-restoration transitions and emergence profiles. CLINICAL SIGNIFICANCE: High-quality no-prep veneers can be more challenging to realize than conventional veneers and the success seems to depend on a combination of good case selection, margins' position, sound adhesive principles, clinical, and laboratory experience.

Canal shaping of different single-file systems in curved root canals.

BACKGROUND/PURPOSE: This study compared maintenance of canal anatomy, occurrence of apical transportation, and working time observed after instrumentation with One Shape New Generation rotary system (Micro-Mega), with those observed after instrumentation with Reciproc (VDW) and WaveOne (Dentsply-Maillefer) reciprocating systems. MATERIALS AND METHODS: The mesial canals of 45 mandibular molars (curvature angles between 35° and 45°) were selected. Specimens were randomly divided into three groups, and canal preparations were performed using One Shape, Reciproc, or WaveOne systems (size #25). A digital double radiographic technique was used to determine apical transportation and change in angle of curvature. Also, working time and instrument failures were recorded. Data were statistically analyzed. RESULTS: During preparation, no file fractured. No statistically significant differences were found among groups. No system showed a significantly faster preparation time than others (P > 0.05). All instruments maintained the original canal curvature well and were safe to use. CONCLUSION: Both continuous rotary instrument and reciprocating systems did not have any influence on the presence of apical transportation or caused an alteration in angle of canal curvature.

Effect of Airborne Particle Abrasion on Microtensile Bond Strength of Total-Etch Adhesives to Human Dentin.

Aim of this study was to investigate a specific airborne particle abrasion pretreatment on dentin and its effects on microtensile bond strengths of four commercial total-etch adhesives. Midcoronal occlusal dentin of extracted human molars was used. Teeth were randomly assigned to 4 groups according to the adhesive system used: OptiBond FL (FL), OptiBond Solo Plus (SO), Prime & Bond (PB), and Riva Bond LC (RB). Specimens from each group were further divided into two subgroups: control specimens were treated with adhesive procedures; abraded specimens were pretreated with airborne particle abrasion using 50 µm Al2O3 before adhesion. After bonding procedures, composite crowns were incrementally built up. Specimens were sectioned perpendicular to adhesive interface to produce multiple beams, which were tested under tension until failure. Data were statistically analysed. Failure mode analysis was performed. Overall comparison showed significant increase in bond strength (p < 0.001) between abraded and no-abraded specimens, independently of brand. Intrabrand comparison showed statistical increase when abraded specimens were tested compared to no-abraded ones, with the exception of PB that did not show such difference. Distribution of failure mode was relatively uniform among all subgroups. Surface treatment by airborne particle abrasion with Al2O3 particles can increase the bond strength of total-etch adhesives.

No-Prep Rehabilitation of Fractured Maxillary Incisors with Partial Veneers.

OBJECTIVE: Therapeutic options for dental trauma depend on the injuries' features. For patients with uncomplicated tooth fractures, adhesive materials and composite partial veneers may be a therapeutic solution that completely preserves healthy tooth structure. CLINICAL CONSIDERATIONS: An ultra-conservative approach, using indirect composite partial veneers to restore fractured anterior teeth is described in these case reports. CONCLUSION: Despite the position of the finish line in the middle of the clinical crown, this solution offers functional and esthetic outcomes using an indirect composite technique, and appears to be a suitable alternative to direct composite restorations or less conservative indirect veneers. CLINICAL SIGNIFICANCE: Indirect composite partial veneers present considerable advantages, such as ultra-minimally invasive properties and excellent esthetic appearances. The success seems to depend on a combination of sound adhesive principles, adequate design of the restoration, laboratory experience, and cementation techniques. (J Esthet Restor Dent 28:351-358, 2016).

Mechanical Properties of Elastomeric Impression Materials: An In Vitro Comparison.

Purpose. Although new elastomeric impression materials have been introduced into the market, there are still insufficient data about their mechanical features. The tensile properties of 17 hydrophilic impression materials with different consistencies were compared. Materials and Methods. 12 vinylpolysiloxane, 2 polyether, and 3 hybrid vinylpolyether silicone-based impression materials were tested. For each material, 10 dumbbell-shaped specimens were fabricated (n = 10), according to the ISO 37:2005 specifications, and loaded in tension until failure. Mean values for tensile strength, yield strength, strain at break, and strain at yield point were calculated. Data were statistically analyzed using one-way ANOVA and Tukey's tests (α = 0.05). Results. Vinylpolysiloxanes consistently showed higher tensile strength values than polyethers. Heavy-body materials showed higher tensile strength than the light bodies from the same manufacturer. Among the light bodies, the highest yield strength was achieved by the hybrid vinylpolyether silicone (2.70 MPa). Polyethers showed the lowest tensile (1.44 MPa) and yield (0.94 MPa) strengths, regardless of the viscosity. Conclusion. The choice of an impression material should be based on the specific physical behavior of the elastomer. The light-body vinylpolyether silicone showed high tensile strength, yield strength, and adequate strain at yield/brake; those features might help to reduce tearing phenomena in the thin interproximal and crevicular areas.

Adhesive Cementation of Indirect Composite Inlays and Onlays: A Literature Review.

The authors conducted a literature review focused on materials and techniques used in adhesive cementation for indirect composite resin restorations. It was based on English language sources and involved a search of online databases in Medline, EMBASE, Cochrane Library, Web of Science, Google Scholar, and Scopus using related topic keywords in different combinations; it was supplemented by a traditional search of peer-reviewed journals and cross-referenced with the articles accessed. The purpose of most research on adhesive systems has been to learn more about increased bond strength and simplified application methods. Adherent surface treatments before cementation are necessary to obtain high survival and success rates of indirect composite resin. Each step of the clinical and laboratory procedures can have an impact on longevity and the esthetic results of indirect restorations. Cementation seems to be the most critical step, and its long-term success relies on adherence to the clinical protocols. The authors concluded that in terms of survival rate and esthetic long-term outcomes, indirect composite resin techniques have proven to be clinically acceptable. However, the correct management of adhesive cementation protocols requires knowledge of adhesive principles and adherence to the clinical protocol in order to obtain durable bonding between tooth structure and restorative materials.

Effects of critical thermal cycling on the flexural strength of resin composites.

We compared flexural strength (FS) in four resin composites before and after three protocols for thermal cycling aging. Four resin composites were evaluated: Enamel Plus Hri, Gradia Direct Posterior, Grandioso, and Grandioso Flow. Sixty specimens (2 × 2 × 25 mm) were fabricated using a split metallic mold and light-cured for 30 s. The specimens were then randomly divided into four groups and tested using one of the following thermal cycling procedures: (1) storage in deionized water for 24 h (control group), (2) 15,000 cycles, 3) 30,000 cycles, and 4) 45,000 cycles. Each thermal cycling procedure was conducted between 5 °C and 55 °C, with a dwell time of 30 s. All specimens were subjected to a three-point bending test, to determine FS (0.5 mm/min). "Material" and "thermal aging" were significantly associated with FS (P < 0.001). A statistically significant interaction between the two factors was also detected (P < 0.001). In the non-aged groups, nanohybrid composites had the highest FS. FS significantly decreased after thermal cycling protocols in all composites tested. Gradia composite exhibited decrease in FS only after 45,000 cycles. In contrast, FS significantly decreased in the Grandioso Flow composite at 15,000 cycles. The trend in the decrease varied among composites, and the decrement in FS was not proportional to baseline values.

Five-year retrospective clinical study of indirect composite restorations luted with a light-cured composite in posterior teeth.

OBJECTIVES: The purpose of this study was to evaluate the clinical performance of indirect composite onlays-overlays bonded with a light-cured composite on vital molars. MATERIALS AND METHODS: Forty-one patients were restored with 79 indirect composite restorations. The restorations were studied for an observation time of 5 years. Marginal adaptation, marginal discolouration, secondary caries, colour match and anatomic form were clinically examined following modified United States Public Health Service criteria. Each restoration was also examined for fractures and debonding. Endodontic complications were registered. Survival rate, based just on failures that required a replacement, and success rate that included also failures that required a repair intervention were statistically determined using a restoration and a patient-related analysis. RESULTS: After 5 years, using each restoration as a statistical unit, the survival rate was 91.1% and the success rate 84.8%, with a high Kaplan-Meier estimated success probability of 0.852. Using the patient as the statistical unit, the survival rate was 90.2% and the success rate 85.4%, corresponding to a Kaplan-Meier estimated success probability of 0.857. On the basis of the criteria used, most of the restorations rated Alpha. Regarding marginal adaptation and marginal discolouration, 5 and 10.1% of the restorations, respectively, revealed Bravo ratings CONCLUSIONS: Indirect composite restorations offer a predictable and successful treatment modality giving an optimal preservation of sound tooth tissue. CLINICAL RELEVANCE: The preparation, cementation and finishing procedures are considered key factors for the long-term success of the indirect composite restorations.

Thermal cycling for restorative materials: does a standardized protocol exist in laboratory testing? A literature review.

In vitro tests continue to be an indispensable method for the initial screening of dental materials. Thermal cycling is one of the most widely used procedures to simulate the physiological aging experienced by biomaterials in clinical practice. Consequently it is routinely employed in experimental studies to evaluate materials' performance. A literature review aimed to elucidate test parameters for in vitro aging of adhesive restorations was performed. This study aims to assess whether or not a standardized protocol of thermal cycling has been acknowledged from a review of the literature. An exhaustive literature search, examining the effect of thermal cycling on restorative dental materials, was performed with electronic database and by hand. The search was restricted to studies published from 1998 to August 2013. No language restrictions were applied. The search identified 193 relevant experimental studies. Only twenty-three studies had faithfully applied ISO standard. The majority of studies used their own procedures, showing only a certain consistency within the temperature parameter (5-55°C) and a great variability in the number of cycles and dwell time chosen. A wide variation in thermal cycling parameters applied in experimental studies has been identified. The parameters selected amongst these studies seem to be done on the basis of convenience for the authors in most cases. A comparison of results between studies would appear to be impossible. The available data suggest that further investigations will be required to ultimately develop a standardized thermal cycling protocol.

Evaluation of a new nickel-titanium system to create the glide path in root canal preparation of curved canals.

INTRODUCTION: Nickel-titanium rotary instruments recently have been introduced with the purpose of creating an initial glide path. The purpose of this study was to compare the maintenance of canal anatomy, the occurrence of apical transportation, and the working time observed using mechanised instrumentation with the new G-File rotary system (Micro-Mega, Besançon Cedex, France) with those observed using instrumentation with the PathFile system (Dentsply Maillefer, Ballaigues, Switzerland) and manual instrumentation with K-type files (Micro-Mega) to create a glide path in curved root canals. METHODS: The mesial canals of 45 mandibular molars (with curvature angles between 25° and 35°) were selected. The specimens were randomly divided into 3 groups with 15 canals each, and canal preparations were performed by an endodontist using #12-17 G-File rotary instruments (group GF), #13-16-19 PathFile rotary instruments (group PF), and #10-15-20 K-type stainless steel manual files (group M). A digital double radiographic technique was used to determine apical transportation and the change in the angle of curvature. The working time was also calculated. RESULTS: No statistically significant differences in the angle of canal curvature and apical transportation were found between the groups. However, concerning the working time, specimens from the group who underwent canal preparation using #12-17 G-File rotary instruments achieved significantly lower mean values when compared with the other 2 groups, whereas the group who underwent canal preparation using the #10-15-20 K-type stainless steel manual files had the highest values. CONCLUSIONS: The G-File rotary instruments, the PathFile system, and the manual instruments did not have any influence on the occurrence of apical transportation nor did they produce a change in the angle of canal curvature. The G-File instruments seemed to be the most rapid system in creating a safe glide path.

Influence of curing time, overlay material and thickness on three light-curing composites used for luting indirect composite restorations.

PURPOSE: To assess the microhardness of three resin composites employed in the adhesive luting of indirect composite restorations and examine the influence of the overlay material and thickness as well as the curing time on polymerization rate. MATERIALS AND METHODS: Three commercially available resin composites were selected: Enamel Plus HRI (Micerium) (ENA), Saremco ELS (Saremco Dental) (SAR), Esthet-X HD (Dentsply/DeTrey) (EST-X). Post-polymerized cylinders of 6 different thicknesses were produced and used as overlays: 2 mm, 3 mm, 3.5 mm, 4 mm, 5 mm, and 6 mm. Two-mm-thick disks were produced and employed as underlays. A standardized amount of composite paste was placed between the underlay and the overlay surfaces which were maintained at a fixed distance of 0.5 mm. Light curing of the luting composite layer was performed through the overlays for 40, 80, or 120 s. For each specimen, the composite to be cured, the cured overlay, and the underlay were made out of the same batch of resin composite. All specimens were assigned to three experimental groups on the basis of the resin composite used, and to subgroups on the basis of the overlay thickness and the curing time, resulting in 54 experimental subgroups (n = 5). Forty-five additional specimens, 15 for each material under investigation, were produced and subjected to 40, 80, or 120 s of light curing using a microscope glass as an overlay; they were assigned to 9 control subgroups (n = 5). Three Vicker's hardness (VH) indentations were performed on each specimen. Means and standard deviations were calculated. Data were statistically analyzed using 3-way ANOVA. Within the same material, VH values lower than 55% of control were not considered acceptable. RESULTS: The used material, the overlay thickness, and the curing time significantly influenced VH values. In the ENA group, acceptable hardness values were achieved with 3.5-mm or thinner overlays after 120 or 80 s curing time (VH 41.75 and 39.32, respectively), and with 2-mm overlays after 40 s (VH 54.13). In the SAR group, acceptable hardness values were only achieved with 2-mm-thick overlays after 120 or 80 s curing time (VH 39.81 and 29.78, respectively). In the EST-X group, acceptable hardness values were only achieved with 3-mm or thinner overlays, after 120 or 80 s curing time (VH 36.20 and 36.03, respectively). CONCLUSION: Curing time, restoration thickness, and overlay material significantly influenced the microhardness of the tested resin composites employed as luting agents. The clinician should carefully keep these factors under control.