CAD/CAM single-retainer monolithic zirconia ceramic resin-bonded fixed partial dentures bonded with two different resin cements: Up to 40 months clinical results of a randomized-controlled pilot study.

PURPOSE: This pilot study was part of a larger study planned for the future which aimed to compare the clinical success of two different resin cements used in the cementation of CAD/CAM single-retainer monolithic zirconia ceramic resin-bonded fixed dentures (RBFPDs). METHODS: Twenty-four RBFPDs were fabricated with monolithic zirconia (Katana™ Zirconia HT, Kuraray Noritake Dental Inc, Tokyo, Japan). Panavia F2.0 (PF2.0; n = 12) and Panavia V5 (PV5; n = 12) were used for cementation. The survival period was defined as the time when the restoration was placed in the mouth and lasted until an irreparable damage occurred. The repairable failures were identified as relative and irreparable failures were identified as absolute failure. The survival rate of the RBFPDs was determined by the Kaplan-Meier estimator. Statistical significance was set at p < 0.05. RESULTS: The mean observation times of the PF2.0 group and the PV5 group were 40.45 ± 6.15 months and 40.18 ± 6.41 months, respectively. Four failures occurred in the PF2.0 group. No failure was observed in the PV5 group. The curves of survival rate (PF2.0 = 80%, PV5 = 100%) showed no statistically significant difference (p = 0.031), although success rate (PF2.0 = 66.7%, PV5 = 100%) showed statistically significant difference (p = 0.317). CONCLUSION: Up to 40 months mean follow-up period, performance of RBFPDs bonded with PV5 was better than with PF2.0. CLINICAL SIGNIFICANCE: For clinicians, it is a matter of hesitation to apply single-retainer RBFPDs. This study contains results of 40 months (minimum 32, maximum 50.47 months) clinical follow-ups of single-retainer RBFPDs. These results will enlighten clinicians about the clinical success of the resin cement type for single-retainer monolithic zirconia ceramic RBFPDs.

Attitudes and perceptions of dental students towards artificial intelligence.

INTRODUCTION: Artificial Intelligence (AI) is a burning topic and use of AI in our day-to-day life has increased exponentially. The purpose of this study was to evaluate the attitudes and perceptions of Turkish dental students towards AI and to provide information about their opinions to use of AI in dentistry. METHODS: A 22-question survey was distributed through Google Forms to all dental students at 9 Turkish dental schools in March 2019. It consisted of various sections aiming to evaluate the dental students' knowledge and attitudes toward AI and possible applications in dentistry. Respondents' anonymity was ensured. RESULTS: A total of 1103 students (650 female, 453 male; mean age was 21.36 ± 1.93 years) responded to the questionnaire for a 21.69% response rate. Of these, about 48.40% had basic knowledge about AI technologies and 10.6% stated that they had no information sources about AI. 85.70% agreed that dentistry would be revolutionized by AI but 28.60% did not agree that AI could replace themselves in the near future. In addition, 74.60% and 79.80% of agreed on topics about AI to be included in undergraduate and postgraduate dental education, respectively. CONCLUSIONS: Although participants have insufficient knowledge of AI, they are willing to improve their knowledge in this field. Participants shared an optimistic views and thought that AI will have a positive impact on dental future practice. Follow-up surveys and multinational studies should be conducted to further explore these issues.

Color match of a feldspathic ceramic CAD-CAM material for ultrathin laminate veneers as a function of substrate shade, restoration color, and thickness.

STATEMENT OF PROBLEM: The final color of a ceramic restoration, especially an ultrathin veneer, is important, but selecting the correct shade is difficult because the substrate can affect the final color of the restoration. PURPOSE: The purpose of this in vitro study was to investigate the effect of substrate shade and thickness on the final color of ultrathin laminate veneers milled from feldspathic ceramic and to present a straightforward methodology with which a clinician can visualize the effects of substrate color, ceramic thickness, and prefabricated computer-aided design and computer-aided manufacturing (CAD-CAM) block color on the final color of the restoration. MATERIAL AND METHODS: All specimens were fabricated by slicing CAD-CAM feldspathic ceramic material with a precision cutter into 12×10-mm slices of approximately 0.35, 0.55, 0.75, and 1.55 mm in thickness with 10 different colors (0M1-1M1-1M2-2M1-2M2-2M3-3M1-3M2-3M3-4M1). As a background substrate, composite resin disks (12×10×2 mm) were fabricated with different shades (0M1 S, 1M1 S, 2M3 S, 3M2 S, 4M3 S, 5M3 S). The CIELab values of the polished surfaces of each specimen were measured on a background (white or simulated foundation) with a spectrophotometer by a single experienced operator, and color differences (ΔE) were calculated. Mean ±SD values were calculated and subjected to ANOVA with 2 variables (substrate and ceramic color) (α=.05). RESULTS: Combinations of a lighter substrate shade and a lighter value ceramic restoration and of a darker substrate shade and darker value ceramic restoration only changed the final color of the restoration minimally. CONCLUSIONS: The final color of a dental restoration is affected by the thickness of the restoration, the substrate color, and the ceramic color. Lighter and darker substrate colors show more color changes, and thin veneers cannot mask the substrate color.

Light transmittance and surface roughness of a feldspathic ceramic CAD-CAM material as a function of different surface treatments.

BACKGROUND: The aim of the present study was to determine the effect of different surface treatments on light transmission of aesthetic feldspathic ceramics used in CAD-CAM chairside restorations. METHODS: Forty eight feldspatic ceramic test specimens were prepared from prefabricated CAD-CAM blocks by using a slow speed diamond saw. Test specimens were prepared and divided into 4 groups (n = 12). In the control group, no surface treatments were applied on the feldspathic ceramic surfaces. In the hydrofluoric acid group, the bonding surfaces of feldspathic ceramics were etched with 9.5 % hydrofluoric acid. In the sandblasting group the feldspathic ceramic surfaces were air-abraded with 30-µm alumium oxide (Al2O3) particles and Er:YAG laser was used to irradiate the ceramic surfaces. The incident light power given by the LED device and the transmitted light power through each ceramic sample was registered using a digital LED radiometer device. Each polymerization light had a light guide with 8-mm-diameter tips. Light transmission of feldspathic ceramic samples was determined by placing it on the radiometer and irradiating the specimen for 10 s at the highest setting for each light polymerization. All specimens were coated with gold using a sputter coater and examined under a field emission scanning electron microscope. Surface roughness measurement each group were evaluated with 3D optical surface and tactile profilometers. RESULTS: One-way ANOVA test results revealed that both surface conditioning method significantly affect the light transmittance (F:412.437; p < 0.001) and the surface roughness values (F:16.386; p < 0.001). Al2O3 and Er-YAG laser application reduced the light transmission significantly (p < 0.05). CONCLUSIONS: The laser and Al2O3 applications reduced the light transmission of 1.5 mm thickness feldspathic ceramic material below the value of 400 mW/cm(2) which is critical limit for safe polymerization.

Color Stability and Surface Roughness of a Laboratory-Processed Composite Resin as a Function of Mouthrinse.

STATEMENT OF THE PROBLEM: Mouthrinses can cause discoloration on indirect resin composites. PURPOSE OF THE STUDY: The purpose of the study was to investigate the effect of different mouthrinses on the color changes and surface roughness of a laboratory-processed composite. METHODS AND MATERIALS: Fifty discs were made using GC Gradia/GC indirect composites and divided into five groups which immersed in artificial saliva and four different types of mouthrinses. The samples were immersed daily for 14 days in 20 mL of the solutions for 2 minutes twice a day (with a 12-hour interval between exposures). Measurements were carried out at four different times: 1 hour after sample preparation (t0 ), 1 day (t1 ), 7 days (t2 ), and 14 days (t3 ) after the first immersion in the solutions. The color before and after immersion was measured according to Comission Internationale de L'Eclairage (CIE L*, a*, b*) System and ΔL*, Δa*, Δb*, and ΔE* values were calculated. The surface roughness Ra (µm) of the specimens was evaluated using a profilometer. RESULTS: There were significant differences between the groups at all time representing ΔE values (p < 0.001). At (t1 ) time representing ΔRa value, there were significant differences between the groups (p < 0.05). At (t2, t3 ) time representing ΔRa values, there were significant differences between the groups (p < 0.001). Pharmol Zn immersed specimens showed ΔE values between 1.04 and 3.67. CONCLUSIONS: The result of this study indicated that the mouthrinses affected the color stability of indirect composites. CLINICAL SIGNIFICANCE: Based on the results of this study, patients with resin composite restorations should be warned by the dentists about the discoloration of the restorations and the time period of the mouthrinse that will be used.

The Effect of Finishing and Polishing Techniques on the Surface Roughness and the Color of Nanocomposite Resin Restorative Materials.

BACKGROUND: Rough, poorly polished surfaces contribute to staining, plaque accumulation, gingival irritation and recurrent caries. Finishing and polishing techniques are critical factors contributing to the longevity of the direct composite resin restorations. OBJECTIVES: The aim of this in vitro study was to evaluate the effects of finishing and polishing systems on surface roughness of six nanocomposite restorative resins. MATERIAL AND METHODS: Thirty specimens of each restorative material (n=180) were placed in a teflon mould (6 mm in diameter and 3 mm in depth) and cured with a LED curing unit. Six specimens from each of restorative material were randomly assigned to four groups for finishing and polishing (carbide burs, diamond burs, aluminium oxide discs, silicon rubber polisher) techniques. Mylar strip formed specimens were served as control group. After finishing and polishing procedures surface roughness was evaluated by a profilometer. The data was analyzed by 2-way analysis of variance and the Tukey HSD test (α=0.05). RESULTS: Significant differences were found between the groups in terms roughness (p<0.001). The control group and aluminium oxide discs group had the lowest Ra values and were significantly different from other groups (p<0.001). The roughest surface was obtained with diamond burs followed by silicon rubbers and carbide burs. Overall, the smoothest surfaces were obtained with the use the complete sequence of aluminum oxide discs. CONCLUSIONS: In areas that could not be reached by the aluminum oxide discs, the carbide burs produced satisfactory surface smoothness for the nanocomposite restorative materials. Although mylar matrix strip formed surfaces presents lower surface roughness values, recountouring and polishing of resin restorations are often required in clinical situations. Aluminium oxide discs and carbide finishing burs are suitable for finishing and polishing procedures for nanocomposite restorative resins.

Multidisciplinary approach for the rehabilitation of central giant cell granuloma: a clinical report.

The central giant cell granuloma (CGCG) is benign, nonodontogenic, and intraosseous lesion of the jaw. Aggressive subtypes of CGCG have a tendency to recur after excision and require wide resection that leads to major defects in the jaw. In this case report a patient who had severe mandibular bony deficiency as a result of excision of aggressive CGCG, orthodontic, and prosthetic treatment was described. The defect was reconstructed with iliac bone graft. Four years later vertical distraction osteogenesis was performed on the grafted mandible in order to obtain a satisfactory bony height of mandibular ridge. After healing period three endosseous dental implants were placed to grafted region. Because of pubertal growth stage, a hybrid removable denture was constructed. The construction of a hybrid removable denture markedly improved the patient's speech, mastication, and appearance. After pubertal growth stage, a fixed partial denture construction was planned and future parts of treatment procedures were described to the patient. Distraction osteogenesis and endosseous dental implants can be a good alternative method for the unsatisfactory reconstructions of mandibular deficiencies.

A modified technique for extraoral cementation of implant retained restorations for preventing excess cement around the margins.

The major drawback of cement-retained restorations is the extrusion of the excess cement into the peri-implant sulcus, with subsequent complications. Insufficient removal of the excess cement may initiate a local inflammatory process, which may lead to implant failure. This article presents a method of controlling cement flow on implant abutments, minimizing the excess cement around implant-retained restorations.

Comparison of digital and conventional impression techniques: evaluation of patients' perception, treatment comfort, effectiveness and clinical outcomes.

BACKGROUND: The purpose of this study was to compare two impression techniques from the perspective of patient preferences and treatment comfort. METHODS: Twenty-four (12 male, 12 female) subjects who had no previous experience with either conventional or digital impression participated in this study. Conventional impressions of maxillary and mandibular dental arches were taken with a polyether impression material (Impregum, 3 M ESPE), and bite registrations were made with polysiloxane bite registration material (Futar D, Kettenbach). Two weeks later, digital impressions and bite scans were performed using an intra-oral scanner (CEREC Omnicam, Sirona). Immediately after the impressions were made, the subjects' attitudes, preferences and perceptions towards impression techniques were evaluated using a standardized questionnaire. The perceived source of stress was evaluated using the State-Trait Anxiety Scale. Processing steps of the impression techniques (tray selection, working time etc.) were recorded in seconds. Statistical analyses were performed with the Wilcoxon Rank test, and p < 0.05 was considered significant. RESULTS: There were significant differences among the groups (p < 0.05) in terms of total working time and processing steps. Patients stated that digital impressions were more comfortable than conventional techniques. CONCLUSIONS: Digital impressions resulted in a more time-efficient technique than conventional impressions. Patients preferred the digital impression technique rather than conventional techniques.

Reverse activated hyrax pressure appliance for treatment of a keloid located at auricula helix.

Keloids are considered aberrations of the wound healing process, and various treatment regimens are described depending on the morphology and size of the lesion. Compression therapy using custom-made pressure clips or splints is widely used for the treatment of keloids. The most common complication of this therapy is ulceration due to excessive soft tissue pressure, resulting in delays and prolonged treatment time. This article describes the fabrication of a custom-made pressure appliance for the treatment of a keloid located at the auricle helix. The pressure appliance can be modified to fit the auricle helix and covers the area needing pressure.

Effects of folk medicinal plant extract Ankaferd Blood Stopper on early bone healing.

OBJECTIVE: Several haemostatic agents are available for clinical use. Ankaferd Blood Stopper (ABS), a mixture of five medicinal plant extracts, has been used historically as a haemostatic agent. The aim of this in vivo study was to investigate the effects of ABS on early bone healing using a rat tibia defect model. MATERIAL AND METHODS: Sixteen male Wistar rats were randomized into two groups of 8 animals each. After deep anesthesia with ketamine, bone defects (3 mm diameter and 2 mm deep) were created in the right and left tibiae of all animals and either treated with 1 cc of ABS (Group 1) or left untreated (Group 2; control). Surgical areas were closed primarily. The animals were sacrificed on the 7th postoperative day and bone samples were collected from the tibias. The samples were examined histopathologically for infection, necrosis, fibrosis, new bone formation and foreign body reaction. The histomorphometric results were analyzed statistically by the chi square test, with the level of significance set at p<0.05. RESULTS: Significant differences were found in both groups in terms of inflammation, necrosis and new bone formation (p=0.001, p=0.0001, p=0.001). No foreign body reaction was observed in the experimental group. ABS application decreased fibrosis in the experimental group, but there were no statistically significant differences from the control group. CONCLUSIONS: Histopathologically, it was observed that the application of ABS decreased the occurrence of inflammation and necrosis, while increasing new bone formation in early bone healing period. Further in vitro and in vivo studies are necessary for evaluating the benefits and possible adverse effects of the application of this herbal product on wound healing.

A survey of cross-infection control procedures: knowledge and attitudes of Turkish dentists.

OBJECTIVES: The objective of this study was to investigate the knowledge, attitudes and behavior of Turkish dentists in Samsun City regarding cross-infection control. MATERIAL AND METHODS: A questionnaire was designed to obtain information about procedures used for the prevention of cross-infection in dental practices and determine the attitudes and perceptions of respondent dental practitioners to their procedures. The study population included all dentists in the city of Samsun, Turkey, in April 2005 (n=184). The questionnaire collected data on sociodemographic characteristics, knowledge and practice of infection control procedures, sterilization, wearing of gloves, mask, use of rubber dam, method of storing instruments and disposal methods of contaminated material, etc. Questionnaire data was entered into a computer and analyzed by SPSS statistical software. RESULTS: From the 184 dentists to whom the questionnaires were submitted, 135 participated in the study (overall response rate of 73.36%). As much as 74.10% dentists expressed concern about the risk of cross-infection from patients to themselves and their dental assistants. Forty-three percent of the participants were able to define 'cross-infection' correctly. The greatest majority of the respondents (95.60%) stated that all patients have to be considered as infectious and universal precautions must apply to all of them. The overall responses to the questionnaire showed that the dentists had moderate knowledge of infection control procedures. CONCLUSIONS: Improved compliance with recommended infection control procedures is required for all dentists evaluated in the present survey. Continuing education programs and short-time courses about cross-infection and infection control procedures are suitable to improve the knowledge of dentists.

A survey of cross-infection control procedures: knowledge and attitudes of Turkish dentists

OBJECTIVES: The objective of this study was to investigate the knowledge, attitudes and behavior of Turkish dentists in Samsun City regarding cross-infection control. MATERIAL AND METHODS: A questionnaire was designed to obtain information about procedures used for the prevention of cross-infection in dental practices and determine the attitudes and perceptions of respondent dental practitioners to their procedures. The study population included all dentists in the city of Samsun, Turkey, in April 2005 (n=184). The questionnaire collected data on sociodemographic characteristics, knowledge and practice of infection control procedures, sterilization, wearing of gloves, mask, use of rubber dam, method of storing instruments and disposal methods of contaminated material, etc. Questionnaire data was entered into a computer and analyzed by SPSS statistical software. RESULTS: From the 184 dentists to whom the questionnaires were submitted, 135 participated in the study (overall response rate of 73.36 percent). As much as 74.10 percent dentists expressed concern about the risk of cross-infection from patients to themselves and their dental assistants. Forty-three percent of the participants were able to define "cross-infection" correctly. The greatest majority of the respondents (95.60 percent) stated that all patients have to be considered as infectious and universal precautions must apply to all of them. The overall responses to the questionnaire showed that the dentists had moderate knowledge of infection control procedures. CONCLUSIONS: Improved compliance with recommended infection control procedures is required for all dentists evaluated in the present survey. Continuing education programs and short-time courses about cross-infection and infection control procedures are suitable to improve the knowledge of dentists.

The effectiveness of denture cleansers on soft denture liners colored by food colorant solutions.

PURPOSE: The aim of this study was to investigate the color stability of soft denture liners and the effectiveness of denture cleansers on soft denture liners colored by food colorants in different time periods. MATERIALS AND METHODS: A plasticized acrylic resin soft liner (Viscogel) and a silicone-based soft liner (Mollosil) were used in this study. From each material 30 specimens (a total of 60 specimens) were prepared in a Teflon mold 15 mm in diameter and 3 mm thick. The prepared specimens were stored in distilled water for 24 hours at 37 degrees C. Initial color measurements of the specimens were made using a small-area colorimeter. The specimens of the two soft liners were divided into three groups each containing 10 specimens. The specimens of the first, second, and third group were immersed for 14 hours (2 hours x 7 days) in 3% erythrosine, tartrazine, and sunset yellow food colorant solutions, respectively. Then the second color measurements were made. After the second measurements, the specimens of each group were divided into two subgroups (n = 5) and were immersed in denture cleansers (Fittydent and Curadent Weekly) for 8 hours, and the third measurements were made. At the end of these procedures, the weekly simulation period was completed. The fourth, fifth, and sixth color measurements were made at the end of the simulation periods for 1, 2, and 3 months, respectively. Color difference (DeltaE) values were calculated, and the derived data were analyzed using repeated measures analysis of variance for three-way classification and Bonferroni multiple comparison tests (alpha= 0.05). RESULTS: There were significant differences between soft liners and cleansers in terms of color change. Mollosil demonstrated mean discoloration values (DeltaE) between 0.81 and 2.66, Viscogel showed DeltaE between 1.26 and 12.83. Viscogel exhibited slightly greater color changes than Mollosil and the results showed significant differences ( p < 0.001). There was no significant difference between the food colorants ( p > 0.05). Denture cleansers showed significant differences ( p < 0.001). Fittydent demonstrated lower DeltaE values than Curadent. CONCLUSION: Silicone-based soft denture lining material seems to be more resistant to staining. With respect to denture cleansers, Fittydent was more effective than Curadent in this trial.

The effects of porcelain polishing systems on the color and surface texture of feldspathic porcelain.

STATEMENT OF PROBLEM: After the adjustment of glazed porcelain surfaces, the surfaces are roughened and must be reglazed or polished with different porcelain polishing systems to improve the esthetic appearance and strength of the porcelain restorations. PURPOSE: The purpose of this in vitro study was to compare the effect of different porcelain polishing methods on the color and surface texture of a feldspathic ceramic. MATERIAL AND METHODS: Ninety porcelain (Vitadur Alpha) discs (10 x 2 mm) were fabricated in a silicone mold and divided into 9 groups (n=10). A medium-grit diamond rotary cutting instrument was used to remove the glaze layer, and then the surface was polished using 1 of the 4 following polishing systems or a combination thereof: polishing paste (Ultra II), polishing stick (Diamond Stick), polishing wheel (CeraMaster), or an adjustment kit (Porcelain Adjustment Kit). No surface treatments were applied to the control group. Color measurements were made using a colorimeter (Minolta CR-321 ChromaMeter) according to the CIE L( *)a( *)b( *) color system. Color differences (DeltaE) between the control group and experimental groups were calculated. The acceptable level was chosen as 3.3 DeltaE units. Then the surface roughness (Ra) (microm) of the same specimens was evaluated using a profilometer. The data were statistically analyzed by 1-way analysis of variance and Tukey HSD tests (alpha=.05). To evaluate the effects of the polishing systems on the ceramic surfaces at a microscopic level, an additional 9 feldspathic ceramic specimens were prepared and polished to represent each of the 9 groups. These specimens were examined under a scanning electron microscope (SEM). RESULTS: Polishing techniques significantly affected the color of the feldspathic ceramic (P<.001). The DeltaE values ranged from 1.03 to 3.36. No significant differences were found within the adjustment kit groups or within the polishing wheel groups. All specimens polished with the various techniques showed significantly different Ra values than the control specimens (P<.001), except for the groups polished using the adjustment kit. The highest Ra and DeltaE values were obtained with the use of polishing paste and polishing stick alone (P<.001). The SEM observations demonstrated that the polishing techniques affected the smoothness of the porcelain surface. CONCLUSIONS: The evaluation of the polishing techniques showed that the use of an adjustment kit alone or preceding polishing paste or polishing stick application created surfaces as smooth as glazed specimens. The use of polishing paste alone did not improve the smoothness of the porcelain surface. The color differences of all groups were found to be at the acceptable level.

Connective tissue grafting on resin ionomer in localized gingival recession.

BACKGROUND: One of the main objectives of periodontal reconstructive surgery is the coverage of exposed roots that occur due to gingival recession. On some occasions, where a caries, root resorption, or amalgam restoration exists on the exposed root surface, the treatment planning becomes more complex. This case report describes the use of a subepithelial connective tissue graft (SCTG) on a resin ionomer-restored root surface to treat gingival recession that is complicated with the above-mentioned handicaps. METHODS: An amalgam restoration and carious lesion were removed following full-thickness flap reflection, and the cavity was restored with glass ionomer cement. An SCTG was placed onto the restoration, and the flap was coronally positioned. A porcelain crown restoration was performed 9 months after surgery. RESULTS: At 3-, 6-, and 9-month follow-ups, probing depths were reduced and gain in attachment level was obtained with no clinical signs of inflammation in gingiva. Monthly periodontal controls revealed that creeping attachment had occurred on the restoration during the follow-up periods. CONCLUSION: This single case report serves as a good example to show that SCTG can be successfully performed to treat gingival recession associated with a glass ionomer-restored root surface.

The evaluation of microleakage and bond strength of a silicone-based resilient liner following denture base surface pretreatment.

STATEMENT OF PROBLEM: The failure of adhesion between a silicone-based resilient liner and a denture base is a significant clinical problem. PURPOSE: The purpose of this study was to examine the effects of denture base resin surface pretreatments with different chemical etchants preceding the silicone-based resilient liner application on microleakage and bond strength. The initial effects of chemical etchants on the denture base resin in terms of microstructural changes and flexural strength were also examined. MATERIAL AND METHODS: Forty-two polymethyl methacrylate (PMMA) denture base resin (Meliodent) specimens consisting of 2 plates measuring 30 x 30 x 2 mm were prepared and divided into 7 groups (n = 6). Specimen groups were treated by immersion in acetone for 30 (A30) or 45 (A45) seconds, methyl methacrylate monomer for 180 (M180) seconds, and methylene chloride for 5 (MC5), 15 (MC15) or 30 (MC30) seconds. Group C had no surface treatment and served as the control. Subsequently, an adhesive (Mollosil) and a silicone-based resilient denture liner (Mollosil) were applied to the treated surfaces, and all specimens were immersed in the radiotracer solution (thalium-201 chloride) for 24 hours. Tracer activity (x-ray counts), as a parameter of microleakage, was measured using a gamma camera. For bond-strength measurement, 84 rectangular PMMA specimens (10 x 10 x 40 mm) were surface-smoothed for bonding and treated with the different chemical etchants using the same previously described group configurations. The adhesive and the silicone-based denture liner were applied to the treated surfaces. Tensile bond-strength (MPa) was measured in a universal testing machine. Flexural strength measurement was performed with 49 PMMA specimens (65 x 10 x 3.3 mm according to ISO standard 1567) in 7 groups (n = 7), with 1 flat surface of each treated with 1 of the chemical etchants preceding adhesive application. The flexural strength (MPa) was measured using a 3-point bending test in a universal testing machine. The data were analyzed by 1-way analysis of variance and the Tukey HSD test (alpha = .05). RESULTS: Significant differences were found between the groups in terms of microleakage (P < .0001). The lowest microleakage was observed in group M180 (30,000 x-ray counts) and the highest in the control group (44,000 x-ray counts). The mean bond strength to PMMA resin ranged from 1.44 to 2.22 MPa. All treated specimens showed significantly higher bond strength than controls (P < .01). The flexural strength values all significantly differed (P < .05). All experimental specimens that had chemical surface treatments showed lower flexural strength than controls (P < .05). CONCLUSION: Treating the denture base resin surface with chemical etchants increased the bond strength of silicone-based resilient denture liner to denture base and decreased the microleakage between the 2 materials. Considering the results of both tests together, the use of methyl methacrylate monomer for 180 seconds was found to be the most effective chemical treatment.