Years Of Clinical Service Research Articles

Marginal quality and wear of extended posterior resin composite restorations: Eight-year results in vivo

AimTo evaluate wear and marginal quality of resin composite restorations over eight years of clinical service in vivo. Methods30 patients received 68 resin composite restorations (36 Grandio, 32 Tetric Ceram) in the course of a prospective clinical trial. 3-D evaluation of 36 selected teeth involving 144 epoxy replicas was carried out using a special 3-D scanning device with an accuracy of U1=2.5+L/350μm; U3=3+L/300μm. In vivo replicas were sputter-coated with gold and examined under a SEM at 200× magnification. Marginal integrity between resin composite and enamel was expressed as a percentage of the entire judgeable margin length. ResultsDuring the clinical 8-year observation period, wear significantly increased in the restored areas as well as in OCAs. RBCs under investigation showed no significant differences regarding wear (p>0.05). Localization of the restorations (premolar vs. molar or upper vs. lower) did not show a significant influence on wear rates (p>0.05). Clinically, by SEM, and by 3-D scanning distinct changes of worn contours on enamel and RBC were visible. Quantitative margin analysis revealed a change of perfect margins (58% at baseline vs. 14% at 8 years), positive step formations (15% at baseline vs. 10% at 8 years), and negative step formations (20% at baseline vs. 71% at 8 years) over time (p<0.001). Regarding the portion of gap-free margins (baseline vs. 2 years) and total margin length (baseline to 8 years), Grandio showed lower values (Mann-Whitney U-test; p<0.05). The portion of negative step formations was lower for Tetric Ceram at baseline (Mann-Whitney-U test; p<0.05). ConclusionsAfter eight years of clinical service, neither wear nor marginal quality was a critical factor for estimation and survival of extended posterior resin composite restorations.

Outcome of zirconia single crowns made by predoctoral dental students: A clinical retrospective study after 2 to 6 years of clinical service

Statement of problemZirconia has established its role as a reliable ceramic material for fixed prostheses. PurposeThe purpose of this retrospective study was to evaluate the outcome of zirconia single crowns made by predoctoral students after 2 to 6 years of clinical service. Material and methodsA cohort of 88 patients treated with zirconia single crowns (mean 3 crowns per patient, range 1 to 12 crowns) from 2007 to 2010 by predoctoral dental students was identified. The patients were invited to attend a clinical examination. ResultsSixty-six participants (75%) took part in the clinical follow-up (30 women and 36 men; mean age 60.4 years, range 19 to 81 years). Altogether, 190 teeth with single crowns were examined, and the mean follow-up time was 3.88 years (1.85 to 6.04 years). The most common complications were chipping of veneering porcelain (4%) and loss of cementation (4%). The success rate of the zirconia single crowns after 2 to 6 years was 80% and the survival rate 89%. ConclusionsZirconia crowns can be successfully used in predoctoral dental education. The success rate of zirconia single crowns after 2 to 6 years was 80% and the survival rate was 89%, in accordance with previous studies.

Thirteen-year randomized controlled clinical trial of a two-step self-etch adhesive in non-carious cervical lesions

ObjectiveThe objective of this randomized controlled clinical trial was to evaluate the 13-year clinical performance of a mild two-step self-etch adhesive in non-carious cervical lesions with and without prior selective phosphoric acid-etching of the enamel cavity margins. MethodsA total of 100 non-carious cervical lesions in 29 patients were restored with Clearfil AP-X (Kuraray Noritake). The composite restorations were bonded following two different approaches: (1) application of Clearfil SE Bond (Kuraray Noritake) following a self-etch approach (CSE-NE); (2) selective phosphoric acid-etching of enamel cavity margins before application of Clearfil SE Bond (CSE-E). The restorations were evaluated after 6 months, 1, 2, 3, 5, 8 and 13 years of clinical service regarding retention, marginal integrity and discoloration, caries occurrence, preservation of tooth vitality and post-operative sensitivity. ResultsThe patient recall rate at 13 years was 62%. Six restorations, 4 of the CSE-NE group and 2 of the CSE-E group, were clinically unacceptable due to loss of retention (1 CSE-NE, 1 CSE-E), a severe marginal defect (2 CSE-NE, 1 CSE-E) and caries occurrence in combination with a severe marginal defect (1 CSE-NE) leading to a clinical success rate of 86% (CSE-NE) and 93% (CSE-E). Ageing of the restorations was characterized by a further increase in the percentage of restorations with a clinically acceptable small marginal defect (CSE-NE: 87%; CSE-E: 83%) and/or superficial marginal discoloration (CSE-NE: 53%; CSE-E: 56%). The presence of small marginal defects (CSE-NE: 86%; CSE-E: 68%) and superficial marginal discoloration (CSE-NE: 41%; CSE-E: 20%) at the incisal enamel side was more frequently noticed in the CSE-NE group than in the CSE-E group. The difference, however, was not statistically significant (McNemar, p>0.05). SignificanceAfter 13 years, the clinical effectiveness of Clearfil SE Bond in non-carious Class-V lesions remained excellent, with selective acid-etching of the enamel cavity margins only having some minor positive effect on marginal integrity and absence of marginal discoloration.

Two-year clinical performance of a two-step etch-and-rinse adhesive in non-carious cervical lesions: Influence of subject's age and dentin etching time.

The aim of this study was to evaluate the influence of the subject's age and dentin etching time on the clinical performance of a two-step etch-and-rinse adhesive in class V non-carious cervical lesions (NCCLs). Forty patients with NCCLs (classified as degrees 2 and 3 of dentin sclerosis) were enrolled in this study. The lesions were selected and assigned into two groups (n = 70/group) according to the subject's age: (G1) between 21-35 years old and (G2) between 40-54 years old. Each group was randomly divided into two subgroups (n = 35/group) according to dentin etching time using recommended application time (15 s) and an extended application time (30 s). A total of 140 restorations with XP Bond (Dentsply DeTrey, Germany) were placed. The composite resin Esthet X (Dentsply) was placed incrementally. All restorations were evaluated using the modified USPHS criteria. Data was analyzed by the McNemar and chi-square tests (p < 0.05). At the end of 2 years, 132 restorations (94.2% recall rate) were evaluated. The 24-month retention rates (%) were 93.5 for G1(15), 97.1 for G1(30), 93.9 for G2(15), and 97.0 for G2(30). There were no statistical differences in the retention rates in each recall period among groups. For the selected age groups, neither the subject's age nor the etching time had any influence on the clinical performance of XP Bond adhesive in NCCLs over a 24-month period. The clinical effectiveness of the XP Bond was excellent after 2 years of clinical service. Long-term clinical evaluations are necessary to confirm this finding.

A retrospective evaluation of zirconia-fixed partial dentures in general practices: An up to 13-year study

ObjectivesTo evaluate zirconia-based fixed partial dentures (FPDs) after more than 8 years in clinical service. MethodsPatients treated between 2000 and 2004 with zirconia FPDs were identified from the records of a manufacturer of FPD substructures. Of the 45 patients who met the inclusion criteria 30 attended the appointment and 33 FPDs were evaluated using modified California Dental Association (CDA) criteria. In addition, plaque and the bleeding index were registered. Patient satisfaction with the restorations was evaluated using a 10-point visual analog scale (VAS). ResultsAll the FPDs were made using CAD/CAM and hot isostatic pressed yttria-tetragonal zirconia polycrystal (HIPed Y-TZP) ceramic (Denzir) and were placed within general practices. The mean observation period was 9.6±1.6 years (range 3.0–13.1 years). The CDA rating was 90% satisfactory for the surface. Corresponding figures for anatomic form, color and margin integrity were 94%, 100% and 94%, respectively. Regarding surface three (9.7%) FPDs exhibited veneer chipping and were rated ‘not acceptable’. For margin integrity two (6.5%) were rated ‘not acceptable’ because of caries. For anatomic form two (6.1%) were rated ‘not acceptable’ due to two lost FPDs. No significant differences were seen between the FPDs and controls for plaque and bleeding. The Kaplan–Meier survival rate (still in clinical function) was 94%, the success rate (technical events accounted for) 91% and (biological events accounted for) 73%. Based on the VAS the mean value for patient satisfaction was 9.3±1.2. SignificanceNinety-four percent of the FPDs were still in clinical function. HIPed Y-TZP could serve as an alternative for FPD treatments similar to those in the current study.

Dynamic mechanical thermal analysis of maxillofacial prosthetic elastomers: the effect of different disinfecting aging procedures.

In this study, dynamic mechanical thermal analysis was used to evaluate the changes that occurred in maxillofacial elastomers subjected to different disinfecting regimens. A commercial polydimethyl siloxane (PDMS) and an experimental chlorinated polyethylene (CPE) were treated with different disinfection procedures for a period that simulates 1 year of clinical service: microwave exposure (D1), hypochlorite solution (D2), neutral soap (D3), and a commercial disinfecting solution (D4). A fifth group was kept in dark storage as control. Dynamic mechanical thermal analysis tests operated in a fixed frequency (1 Hz) over a range of temperatures (-130°C to 20°C for PDMS, -60°C to 120°C for CPE). Loss modulus (G″), storage modulus (G'), and loss factor (tanδ) were recorded as a function of temperature. The obtained glass transition temperature (Tg) values were subjected to statistical analysis. Dynamic mechanical thermal analysis revealed changes in Tg values for both materials, which reflect the possible changes in their chemical and physical structure, after different disinfection procedures. The PDMS and CPE samples seem to have less dense structure maybe because of chain scission reaction that probably occurred during the disinfection procedures. According to statistical analysis, Tg values presented significant changes from the control samples among the different materials and disinfecting procedures. Microwave exposure and hypochlorite solution affect CPE significantly, whereas PDMS exhibited significant changes after being treated with a commercial antimicrobial agent, concerning changes that occurred in Tg. In all cases, Tg values were decreased compared with the untreated samples, which were stiffer, presenting higher Tg and G' values.

Zirconia ceramic single-retainer resin-bonded fixed dental prostheses (RBFDPs) after 4 years of clinical service: a retrospective clinical and volumetric study.

The aim of this study was a retrospective assessment of the up to 8-year clinical outcomes of zirconia ceramic single-retainer resin-bonded fixed dental prostheses (RBFDPs). Fifteen subjects (9 women, 6 men) with 15 anterior zirconia ceramic RBFDPs were included. The RBFDPs replaced 5 maxillary central incisors, 7 maxillary lateral incisors, and 3 mandibular lateral incisors. The patients willing to participate were recalled and the survival of the RBFDPs was assessed. The technical outcome was evaluated with modified United States Public Health Service criteria. Fracture and/or chipping of the restoration, occlusal wear, marginal adaptation, marginal discoloration, shape, surface texture, and esthetic integration were recorded. Biologic parameters were assessed, including vitality, probing pocket depth, gingival recession, plaque control record, bleeding on probing, and periodontal mobility. Data were descriptively analyzed using a paired t test (P < .05). Fifteen subjects with 15 RBFDPs were examined after a mean follow-up period of 53.3 months (SD, 23 months). No catastrophic failures occurred. The 4-year survival rate was 100%. Two early debondings occurred with successful recementation. No chipping of the veneering ceramic occurred. No differences in biologic outcomes between test and control teeth were found. The zirconia ceramic RBFDPs exhibited excellent clinical results in anterior regions and had a positive effect on the esthetic outcomes of the pontic regions.

A split-mouth randomized clinical trial of conventional and heavy flowable composites in class II restorations

ObjectiveThe aim of this study was to evaluate the 2-year clinical performance of class II restorations made with a composite resin with two different viscosities. Methods47 patients received two class II restorations (n=94), one made with GrandioSO (conventional viscosity – CV), and the other with GrandioSO Heavy Flow (flowable viscosity – FV), subjecting both materials to the same clinical conditions. The self-etching adhesive Futurabond M was used for all restorations. The composites were inserted using the incremental technique. The restorations were evaluated using the modified USPHS criteria according to the periods: baseline, 6 months, 1 year and 2 years after restorative procedures. ResultsAfter 24 months, 40 patients attended the recall and 78 restorations were evaluated. In all periods, no secondary caries was observed. After 6 months, there were slightly overall changes of scores for most parameters. After 24 months, the higher number of changes from score Alfa to Bravo was observed for marginal discolouration (32.5% – CV and 39.5% – FV) and colour match (15% – CV and 31.6% – FV), followed by proximal contact (25% – CV and 23.7% – FV) and marginal adaptation (20% – CV and 21.1% – FV). For wear, surface texture and postoperative sensitivity the changes were very small. Just two restorations were lost during the 24-month follow up. Less than 5% of all restorations showed postoperative sensitivity. Chi-square test showed no significant differences between the two materials for all parameters analysed. ConclusionAfter 2 years of clinical service, no significant differences were observed between GrandioSO conventional and GrandioSO Heavy Flow for the parameters analysed. Both materials provided acceptable clinical behaviour in class II restorations. Clinical SignificanceThis study presents the possibility of using a flowable composite with high filler content, for performing class II restorations.

One year clinical follow up of nano filled glass ionomer and composite resin restorations

BackgroundThe authors evaluated the clinical performance of a nano filled glass ionomer restorative material (Ketac N100) and a nano filled composite resin restorations (Grandio SO) with its adhesive (Futurabond DC) in Class V carious lesions over one year. MethodsThirty patients received sixty different restorations. The distributions of materials and the teeth locations were randomized. Class V cavity was prepared according to caries extension. For cavities to be restored with composite a 1 mm bevel was placed on the enamel margin to increase the surface area for bonding. adhesives were used following the manufacturer's instructions. Grandio SO with its adhesive and Ketac N100 restorative materials were applied following manufacturer's instructions. Finishing and polishing was performed using finishing burs and polishing discs. Each restoration was clinically evaluated at base line (24 h), 6 months and after one year using USPHS criteria. ResultsThe recall rate was (81.7%) after 1 year. Survival rate for Grandio SO restorations were (85.185%) while for Ketac N100, it was (100%) after one year of clinical service. Using Friedman test, a significant difference was recorded between the tested materials when the effect of time was tested on restoration fracture, color match, anatomic form, marginal adaptation and recurrence of caries. Using Fischer's exact test, a significant difference was recorded between tested groups regarding restoration fracture, color match. Anatomic form, recurrence of caries, marginal discoloration and postoperative hypersensitivity. ConclusionMost of the restorations maintained good quality during the observation period, which was considered a short evaluation time. Clinical implicationsGrandio SO and Ketac N100 achieved clinically acceptable results after one year of service. So both materials may be used with confidence in Class V carious lesions. A longer evaluation period may be recommended to decide the use of restorative material safely in Class V cavities.

Transition from failing dentition to complete-arch implant rehabilitation with a staged approach: A 3-year clinical report

The transition of patients from failing dentition to complete-arch implant rehabilitation often means that the patient is rendered edentulous and has to wear a removable complete denture for a time. Many patients find this objectionable. A staged treatment approach provides a fixed interim prosthesis for use throughout the rehabilitation process, allowing patient comfort and prosthodontic control. This clinical report describes a staged approach protocol with a new type of interim prosthesis. The prosthesis is supported by hopeless teeth and the soft tissues of the maxillary tuberosities and mandibular retromolar pads for the complete-arch implant rehabilitation of a patient with failing dentition. This protocol allows for a fixed interim prosthesis with combined tooth and mucosa or implant support during the entire rehabilitation process, thusavoiding the use of complete dentures. The implants and prostheses were functioning successfully after 3 years of clinical service.

Single crowns with CAD/CAM-fabricated copings from titanium: 6-year clinical results

Computer-aided design/computer-aided manufacturing (CAD/CAM) titanium ceramic restorations were developed with the potential for replacing expensive, high noble metal ceramic restorations. However, little information exists about the clinical performance of CAD/CAM titanium ceramic single crowns. The purpose of this study was to evaluate CAD/CAM titanium ceramic single crowns after 6 years in function. A total of 41 crowns were fabricated for 21 patients. The titanium copings were CAD/CAM milled (Everest CAD/CAM system), with an even thickness of 0.5 mm and veneered with low-fusing porcelain (Vita Titanium Porcelain) in the powder-build-up technique. All the crowns were cemented with zinc phosphate. The participants were recalled at 12, 24, 36, 48, 60, and 72 months after cementation to document any mechanical and biologic complications and to measure the periodontal parameters, such as probing depth, bleeding on probing, and the plaque index. The success and survival rates were calculated according to the Kaplan-Meier analysis. After 6 years of clinical service, 12 mechanical complications and 1 biologic complication were found, which resulted in a success rate of 67.8%. The cumulative survival rate of the crowns was 91.3% after 6 years. At the end of the follow-up period, the probing depth was 3.21 mm, the percentile of surface with bleeding on probing was 25, and the plaque index was 0.37. No secondary caries or decementation was detected during the 6-year observation period. The clinical performance of the CAD/CAM titanium-ceramic crowns after 6 years was poor because of veneering porcelain problems. Recent CAD software with tools to design proper copings might improve the clinical success.

Clinical performance of cantilevered fixed dental prostheses abutments in the shortened dental arch

ObjectivesThis article is part of a randomized clinical trial on different treatments in the shortened dental arch (SDA). It focused on the abutment tooth prognosis with cantilevered fixed dental prostheses (CFDPs). MethodsSixty-two patients with a bilaterally SDA up to the first or second premolar in the mandible or maxilla were evaluated. In 57 of 124 quadrants, second premolars were replaced by a CFDP (cantilever group). In the remaining 67 quadrants, a natural second premolar was present and thus no need for a CFDP was given (non-cantilever group). Patients were recalled annually up to 5 years. ResultsThe mean observation period was 56.3 months (min. 3.0, max. 76.2, SD 16.1). Kaplan–Meier survival rates concerning tooth loss and tooth fracture were 93.9%/94.0% in the cantilever group and 91.9%/92.8% in the non-cantilever group. Differences between both groups were not significant. The survival rate concerning loss of retention of CFDP retainers was 92.1% in the cantilever group. ConclusionAfter 5 years of clinical service, CFDPs for the replacement of the second premolar showed no negative impact on the abutment tooth prognosis. Clinical significanceCantilevered fixed dental prostheses present a viable treatment option in the shortened dental arch without compromising the medium-term abutment tooth prognosis.

Are there universal restorative composites for anterior and posterior teeth?

ObjectiveThis retrospective, longitudinal clinical study investigated the longevity up to 20 years of posterior restorations placed with 3 universal composites (Charisma, Herculite XR, Z100) and of anterior restorations placed with 2 universal composites (Charisma, Herculite XR). MethodsRecords from 90 patients were retrieved from a private practice (374 posterior, 219 anterior restorations). Clinical evaluation was performed by the FDI criteria. Survival analysis was assessed using Kaplan–Meier method and Log-Rank test, and factors associated with failure by multivariate Cox regression with shared frailty. ResultsIn the first 10 years, almost 95% of the restorations were satisfactory, showing increased failure thereafter. Charisma showed the most failures in anterior and posterior areas. Annual failure rates varied between 0.3% and 2.5%, with slightly better performance for anterior restorations. Fracture (posterior) and aesthetics (anterior) were the main reasons for failure. Clinical significanceDifferences were observed between restorative materials with different properties, but these became apparent only after more than 10 years of clinical service. The present study provides evidence that in a patient group with low caries risk, anterior and posterior restorations placed with universal composites may have excellent long-term clinical performance.

Five-year clinical performance of a HEMA-free one-step self-etch adhesive in noncarious cervical lesions

The objective of this randomized controlled trial was to evaluate the clinical performance of a 2-hydroxyethyl methacrylate (HEMA)-free one-step adhesive. Two hundred sixty-seven cervical lesions in 52 patients were restored with the composite Gradia Direct (GC), bonded with either the one-step self-etch adhesive G-Bond (GC) or the three-step etch-and-rinse adhesive Optibond FL (Kerr) in a random order. The restorations were evaluated for retention, marginal integrity, marginal discoloration, and caries occurrence after 5 years. Specific statistics were used to account for the clustered data (multiple restorations per patient). The clinical success rate for G-Bond (87.4 %) was not significantly different from that of Optibond FL (90.9 %). Both adhesives showed progressive marginal deterioration, but G-Bond exhibited more small enamel defects and marginal discoloration, and unlike previous recalls, several restorations failed because of deep microleakage. Large sclerotic lesions were a significant risk factor for retention loss with G-Bond. Irrespective of the adhesive, almost all restorations with retention loss were located in the lower jaw. After 5 years of clinical service, restorations bonded with the HEMA-free one-step adhesive did not need repair or replacement more often than those with the three-step etch-and-rinse adhesive, and both adhesives had a high retention rate (>90 %). There were indications that G-Bond did not (self-)etch enough in some clinical situations, as G-Bond exhibited more incisal defects and marginal discolorations, and sclerotic lesions were at higher risk of retention loss. The clinical performance of the HEMA-free one-step adhesive was clinically acceptable after 5 years.

Effect of different disinfecting procedures on the hardness and color stability of two maxillofacial elastomers over time

Objective:Disinfection procedures often cause deterioration in a maxillofacial prosthesis. Color and hardness alterations could lead to a replacement of the prosthesis. Material and Methods:An experimental chlorinated polyethylene (CPE) and a commercial polydimethyl siloxane (PDMS) sample were treated with four different disinfection procedures for a period which simulates 1 year of clinical service. The applied disinfection procedures included microwave exposure and immersion in three solutions, sodium hypochlorite, neutral soap and a commercial disinfecting soap. Shore A hardness (ΔΗ) and color differences (ΔΕ) were determined before and after each procedure. All data were analyzed by Two Way Analysis of Variance (ANOVA) and Tukey's post hoc tests at a level of α=0.05. Results:The samples presented significant alterations in color and hardness after the different disinfection treatments. The color differences (ΔΕ) were at least eye detectable in all cases and clinically unacceptable in most of the cases, with values ranging from 1.51 to 4.15 and from 1.54 to 5.92 for the PDMS and CPE material, respectively. Hardness was decreased after all the disinfection procedures in the PDMS, while for the CPE, a decrement was observed after disinfection with sodium hypochlorite and neutral soap and an increment after microwave exposure and the disinfection with a commercial antimicrobial agent. The PDMS samples presented greater alterations in color and hardness after disinfection with sodium hypochlorite solution, while the microwave exposure caused negligible effects. The CPE samples were affected most after disinfection when treated with neutral soap, and more slightly when disinfected with sodium hypochlorite solution. Conclusions:The disinfection procedures caused alterations in color and hardness of the examined materials. The most suitable disinfection procedure for the PDMS material is microwave exposure, while disinfection with sodium hypochlorite solution is not recommended. The CPE material is suggested to be disinfected with sodium hypochlorite solution and the use of neutral soap is not recommended. Comparing the two materials, the PDMS material is most color stable, while the CPE material presented fewer changes in hardness.

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

ObjectivesTo examine the strength and mode of fracture of traditionally and minimally prepared all-ceramic resin bonded CAD/CAM crowns after fatigue loading. MethodsThirty 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). ResultsThe 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. SignificanceMinimal 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.

Nanohybrid vs. fine hybrid composite in extended class II cavities: 8-year results

In a controlled prospective split-mouth study, clinical behavior of two different resin composites in extended class II cavities was observed over 8 years. Thirty patients received 68 direct resin composite restorations (Solobond M/Grandio, Voco--n = 36; Syntac/Tetric Ceram, Ivoclar Vivadent--n = 32) by one dentist in a private practice. Thirty-five percent of cavities revealed no enamel at the bottom of the proximal box, 48% of cavities provided <0.5 mm remaining proximal enamel width. Restorations were examined according to modified US Public Health Service criteria at baseline, after 6 months, and 1, 2, 4, 6, and 8 years. All patients attended the 8-year recall. The overall success rate of all restorations was 98.5% (Kaplan-Meier survival algorithm). One Grandio restoration was lost due to bulk fracture. One Tetric Ceram restoration suffered drop out due to cusp fracture having been not related to the restoration itself. Neither restorative materials nor localization of the restorations had a significant influence on any criterion except color (darker for Grandio). Restorations in molars performed inferior compared with premolars regarding marginal integrity (4 years), restoration integrity (6, 12, 24, 48, and 96 months), and tooth integrity (12, 48, 72, and 96 months). Irrespective of the resin composite used, significant changes over time were found for all criteria evaluated in clinical examinations. Beyond the 4-year recall, marginal staining increased. Both phenomena were found earlier in molars compared with premolars. Tooth integrity significantly deteriorated because of increasing enamel cracks and chippings over time. Both materials performed satisfactorily over the 8-year observation period. Due to the extension of the restorations, wear was clearly visible after 8 years of clinical service. Hybrid and nanohybrid resin composites show an acceptable clinical performance after 8 years of service.

Wear of metal-free resin composite crowns after three years in service

To compare differences between the wear behavior of two types of metal-free resin composite crown with a control after three years in clinical service. Sixty-six participants needing one to three posterior single crowns were fitted with 120 crowns. Abutment teeth were randomly assigned to three groups: 40 resin composite crowns with fiber-reinforced framework, 40 resin composite crowns without fiber-reinforced framework, and 40 metal-ceramic crowns. To assess wear, gypsum replicas of the crowns were fabricated and scanned with a 3D laser scanner at baseline and after three years. Differences between the groups were analyzed by use of mixed-effects regression models. Wear of resin composite crowns with fiber-reinforced framework (p=0.0043) and resin composite crowns without framework (p=0.0246) was significantly greater than in the metal-ceramic group. Wear of metal-free resin composite crowns after three years was significantly greater than that of metal-ceramic crowns, but the wear was still clinically acceptable.

Four-year clinical evaluation of a self-adhesive luting agent for ceramic inlays

The aim of this randomized controlled clinical trial was to evaluate the 4-year clinical performance of a self-adhesive resin cement, RelyX Unicem (3M ESPE), used for cementation of ceramic inlays. In addition, the influence of selectively acid-etching enamel prior to luting on the clinical performance of the restorations was assessed. Sixty-two IPS Empress 2 inlays/onlays were placed in 31 patients by two experienced clinicians. The restorations were luted with RelyX Unicem with (=experimental group: E) or without (=control group: NE) prior enamel etching with phosphoric acid. At baseline, 6 months, and 1, 2, and 4 years after placement, the restorations were assessed by two calibrated investigators using modified USPHS criteria. Ten selected samples of each group were investigated under SEM regarding morphological changes at the cement-inlay interface. The recall rate at 4 years was 97%. Two restorations (1 E, 1 NE) were lost, and one (E) had to be replaced due to inlay and tooth fracture resulting in a survival rate of 95%. No significant differences between the experimental and control group were noticed regarding all criteria (McNemar, p < 0.05). An obvious deterioration in marginal integrity was observed after 4 years as only 5% (E = 7%; NE = 3%) of the restorations exhibited an excellent marginal adaptation. In 90% of the restorations small, still clinically acceptable marginal deficiencies were observed. SEM of the luting gap showed an increased wear of the RelyX Unicem cement over the 4-year period. The self-adhesive luting cement RelyX Unicem can be recommended for bonding of ceramic inlays/onlays. Additional selective enamel etching does not improve the clinical performance of the restorations within the 4-year period. The self-adhesive resin composite RelyX Unicem showed acceptable clinical performance after 4 years of clinical service.

Effect of veneering technique on the fracture resistance of zirconia fixed dental prostheses

To compare the fracture resistance of zirconia 3-unit posterior fixed dental prostheses (FDPs) frameworks veneered with different veneering materials and techniques before and after artificial ageing. Forty-eight zirconia 3-unit FDPs, representing a missing first molar, were adhesively cemented on human teeth. The zirconia frameworks were randomly distributed according to the veneering materials and techniques into three groups, each containing 16 samples: group LV (layering technique/Vintage ZR), group LZ (layering technique/ZIROX) and group PP (CAD/CAM and press-over techniques/PressXZr). Half of each group was artificially aged through dynamic loading and thermocycling to simulate 5 years of clinical service. Afterwards, all specimens were tested for fracture resistance using compressive load. An analysis of variance (anova) was used to assess the effect of veneering ceramic and artificial ageing on fracture resistance (P < 0·05). Except for one minor cohesive chipping in group LV1, all specimens survived artificial ageing. The mean fracture resistance values (in Newton) of different non-aged (± s.d.)/aged (± s.d.) groups were as follows: LV0 2034 (± 401)/LV1 1625 (± 291); LZ0 2373 (± 718)/LZ1 1769 (± 136); and PP0 1959 (± 453)/PP1 1897 (± 329). Artificial ageing significantly reduced the fracture resistance in groups veneered with the layering technique (P < 0·05), whereas no significant effect was found in specimens veneered with the CAD/CAM and press-over techniques. All tested systems have the potential to withstand occlusal forces applied in the posterior region. The combination of the CAD/CAM and press-over techniques for the veneering process improved the overall stability after artificial ageing, relative to the layering technique.