Clinical outcomes following atrophic alveolar ridge reconstruction using collagenated xenogeneic bone block or autogenous bone block: One-year follow-up of a randomized controlled clinical.

AIM: This investigation aimed to evaluate the 1-year survival of implants placed after staged lateral alveolar ridge augmentation using equine-derived collagenated xenogeneic bone blocks (CXBBs) or autogenous bone block (ABB). MATERIALS AND METHODS: Fifty patients who underwent lateral augmentation in a previous trial were included. The primary outcome measure was implant survival at the 1-year follow-up, and secondary outcomes included implant success, peri-implant clinical and volumetric parameters, pink aesthetic scores (PES) and patient-reported outcome measures. Data analysis involved Fisher's exact test, the Mann-Whitney U-test and the Wilcoxon signed-rank test. RESULTS: In this study, no late implant failures were observed. The cumulative survival rates were 78.6% for the CXBB group and 90.9% for the ABB group, with no difference between the groups. Similarly, the success rates were 53.6% and 63.6%, respectively, showing no significant difference. Peri-implant clinical and volumetric parameters indicated the presence of healthy peri-implant tissues surrounding implants placed in both CXBB- and ABB-augmented sites. PES were 8.5 and 11.0 for implants placed in CXBB- and ABB-augmented sites, respectively. Furthermore, patient satisfaction rates were high and similar between the groups. CONCLUSIONS: Dental implants placed in both CXBB- and ABB-augmented ridges demonstrated no statistically significant differences in clinical, volumetric and aesthetic outcomes, along with high patient satisfaction rates.

Radiographic outcomes of ridge reconstruction with autogenous bone block versus collagenated xenogeneic bone block: A randomized clinical trial.

AIM: To compare, at different levels from the alveolar crest, the radiographic outcomes of equine-derived collagenated xenogeneic bone blocks (CXBB) and autogenous bone blocks (ABB) used for lateral alveolar ridge augmentation. MATERIALS AND METHODS: Sixty-four patients with tooth gaps in atrophic alveolar ridges with ≤4 mm were randomly assigned to lateral augmentation using CXBB or ABB. The lateral bone thickness (LBT) was measured 2, 4, 6, 8, and 10 mm below the alveolar crest using CBCT scans obtained before augmentation surgery and at 30 weeks, prior to implant placement. Statistical analysis was performed using Shapiro-Wilk, Fisher's exact, Mann-Whitney, and Wilcoxon signed-rank tests. RESULTS: Both CXBB and ABB resulted in significant total and buccal LBT gains at 2, 4, 6, 8, and 10 mm. LBT gains were similar between CXBB- and ABB-augmented sites, except for greater buccal LBT gains at 8 mm at CXBB-augmented sites. While ABB-augmented sites gained vertical bone height, CXBB-treated sites suffered vertical bone loss (CXBB: -0.16 mm; ABB: 0.38 mm, p < .0009). CONCLUSIONS: CXBB and ABB were both associated with significant and similar LBT gains at 30 weeks.

13-year follow-up of a randomized controlled study on zirconia and titanium abutments.

OBJECTIVES: To assess survival rates and compare technical, biological, and esthetic outcomes of customized zirconia and titanium abutments at 13 years post loading. MATERIALS AND METHODS: Initially, 22 patients with 40 implants in posterior regions were included. The sites were randomly assigned to 20 customized zirconia abutments with cemented all ceramic crowns (ACC) and 20 customized titanium abutments with cemented metal ceramic crowns (MCC). At a mean follow-up of 13.4 years, patients were examined and implants/restorations assessed for survival and technical complications, as well as biological and esthetic outcomes (pocket probing depth [PPD], bleeding on probing [BOP], plaque control record [PCR], bone level [BL], papilla index [PAP], mucosal thickness, and recession (distance of the margo mucosae [MM]/margo gingivae MG)). Descriptive analyses were performed for all outcome measures. RESULTS: Fifteen patients with 21 abutments (13 zirconia, 8 titanium) were examined at 13 years. The drop-out rate was 25% (patient level). The technical survival rate of the abutments was 100%. The survival rate on the restorative level (crowns) was 100%. The assessed biological outcomes (PPD, PCR, BOP, BL) and esthetic outcomes (MG, PAP) were similar. CONCLUSIONS: Zirconia and titanium abutments supporting single implant-borne restorations rendered a high survival rate and minimal differences in terms of technical, biological, and esthetic outcomes at 13 years of follow-up.

Autogenous bone block versus collagenated xenogeneic bone block in the reconstruction of the atrophic alveolar ridge: A non-inferiority randomized clinical trial.

AIM: To compare the efficacy of equine-derived collagenated xenogeneic bone blocks (CXBB) and autogenous bone block (ABB) for lateral alveolar ridge augmentation and two-stage implant placement. MATERIALS AND METHODS: Sixty-four patients with tooth gaps up to four teeth and atrophic alveolar ridges with ≤4 mm were randomly assigned to lateral augmentation using CXBB or ABB. Lateral bone thickness (LBT) was measured 2 mm below the alveolar crest at augmentation surgery and 30 weeks later at implant placement. Implant-related outcomes, adverse events, surgery duration, pain sensation, analgesic consumption, and oral health-related quality of life were also assessed. Data were analysed using Fisher's exact, Mann-Whitney, and Wilcoxon signed-rank tests. RESULTS: At 30 weeks, the median change in LBT amounted to 2.90 (CXBB) and 3.00 (ABB), respectively. Secondary endpoints demonstrated similar results for CXBB and ABB in terms of possibility to place an implant, need to perform a secondary bone augmentation at implant placement and rate of complications. Early implant failure was 20% for CXBB and 10% for ABB, with no difference between the groups. Pain scores and post-operative consumption of analgesics were significantly lower in the CXBB group than in the ABB group, especially during the first days post-surgery. CONCLUSIONS: CXBB is non-inferior to ABB for horizontal alveolar ridge augmentation and two-stage implant placement.

Peri-implant tissue changes at sites treated with alveolar ridge preservation in the aesthetic zone: Twenty-two months follow-up of a randomized clinical trial.

AIM: To compare tissue changes at implant sites previously treated with two biomaterials for alveolar ridge preservation (ARP) in the aesthetic zone, 1 year after restoration. MATERIALS AND METHODS: Sixty-six participants were treated with ARP using demineralized bovine bone mineral (DBBM) or DBBM +10% of collagen (DBBM-C), both covered with a collagen matrix (CM). Dental implants were placed, and definitive crowns were installed. Silicon impressions were taken before tooth extraction (T0), 2 weeks after crown insertion (T1) and 1 year after restoration (T2). Mid-facial mucosal level change (MLC), soft tissue thickness changes (TT), and marginal bone loss (MBL) were analysed using inter-group comparisons. RESULTS: Fifty-four participants were included in the analysis. The mid-facial level change between T0-T1 and T1-T2 showed no statistical difference between DBBM and DBBM-C. Between T0 and T1 for soft tissue thickness, DBBM performed significantly better at 3 and 5 mm below the mucosal margin. From T1 to T2, no significant differences between groups were found at any level for soft tissue thickness and MBL. CONCLUSION: At the aesthetic zone, advanced recession from tooth extraction to crown placement can be expected at sites treated with ARP regardless of biomaterial used. However, after crown insertion, tissue stability can be predicted.

Zirconia implants restored with single crowns or fixed dental prostheses: 5-year results of a prospective cohort investigation.

AIM: To evaluate the clinical and radiological outcomes of one-piece zirconia implants restored with single crowns (SCs) or fixed dental prostheses (FDPs) over an observation period of 5 years in function. MATERIALS AND METHODS: In a prospective cohort investigation with two investigational centers, one-piece zirconia implants were placed in anterior and posterior sites. After a healing period of at least 2 months in the mandible and 4 months in the maxilla with immediate provisional reconstructions, the final all-ceramic SCs or three-unit FDPs were cemented. Patients were followed for 5 years. Clinical parameters and radiological measurements of the implants and the neighboring teeth were assessed. For the statistical analysis, linear mixed models were applied. RESULTS: A total of 71 implants were placed in 60 patients. Sixty-three implants in 53 patients could be evaluated at the 5-year follow-up. Six patients with a total of seven implants were counted as dropouts. One implant did not achieve adequate osseointegration and had to be removed 5 weeks after implantation. The 5-year survival rate was calculated as 98.4% (95% CI 91.6, 99.9). The mean overall marginal bone loss from implant placement to the 5-year follow-up was 0.7 ± 0.6 mm. After an initial mean marginal loss before loading the implants (0.7 mm), no further statistically significant change in marginal bone level (p = .458) could be observed. CONCLUSION: The investigated one-piece zirconia implant showed a high survival rate, very stable marginal bone, and mucosal margin levels after 5 years in function. Therefore, it can be considered safe and reliable for the reconstruction of implant-supported SCs or FDPs over a mid-term period.

Influence of wound closure on volume stability with the application of different GBR materials: an in vitro cone-beam computed tomographic study.

PURPOSE: To assess the influence of using different combinations of guided bone regeneration (GBR) materials on volume changes after wound closure at peri-implant dehiscence defects. METHODS: In 5 pig mandibles, standardized bone defects were created and implants were centrally placed. The defects were augmented using different combinations of GBR materials: xenogeneic granulate and collagen membrane (group 1, n=10), xenogeneic granulate and alloplastic membrane (group 2, n=10), alloplastic granulates and alloplastic membrane (group 3, n=10). The horizontal thickness was assessed using cone-beam computed tomography before and after suturing. Measurements were performed at the implant shoulder (HT0) and at 1 mm (HT1) and 2 mm (HT2) below. The data were statistically analysed using the Wilcoxon signed-rank test to evaluate within-group differences. Bonferroni correction was applied when calculating statistical significance between the groups. RESULTS: The mean horizontal thickness before suturing was 2.55±0.53 mm (group 1), 1.94±0.56 mm (group 2), and 2.49±0.73 mm (group 3). Post-suturing, the values were 1.47±0.31 mm (group 1), 1.77±0.27 mm (group 2), and 2.00±0.48 mm (group 3). All groups demonstrated a loss of horizontal dimension. Intragroup changes exhibited significant differences in group 1 (P<0.001) and group 3 (P<0.01). Intergroup comparisons revealed statistically significant differences of the relative changes between groups 1 and 2 (P=0.033) and groups 1 and 3 (P=0.015). CONCLUSIONS: Volume change after wound closure was minimized by using an alloplastic membrane. The stability of the augmented horizontal thickness was most ensured by using this type of membrane irrespective of the bone substitute material used for membrane support.

Tissue integration of zirconia and titanium implants with and without buccal dehiscence defects.

PURPOSE: The purpose of the present study was to validate an experimental model for assessing tissue integration of titanium and zirconia implants with and without buccal dehiscence defects. METHODS: In 3 dogs, 5 implants were randomly placed on both sides of the mandibles: 1) Z1: a zirconia implant (modified surface) within the bony housing, 2) Z2: a zirconia implant (standard surface) within the bony housing, 3) T: a titanium implant within the bony housing, 4) Z1_D: a Z1 implant placed with a buccal bone dehiscence defect (3 mm), and 5) T_D: a titanium implant placed with a buccal bone dehiscence defect (3 mm). The healing times were 2 weeks (one side of the mandible) and 6 weeks (the opposite side). RESULTS: The dimensions of the peri-implant soft tissue varied depending on the implant and the healing time. The level of the mucosal margin was located more apically at 6 weeks than at 2 weeks in all groups, except group T. The presence of a buccal dehiscence defect did not result in a decrease in the overall soft tissue dimensions between 2 and 6 weeks (4.80±1.31 and 4.3 mm in group Z1_D, and 4.47±1.06 and 4.5±1.37 mm in group T_D, respectively). The bone-to-implant contact (BIC) values were highest in group Z1 at both time points (34.15%±21.23% at 2 weeks, 84.08%±1.33% at 6 weeks). The buccal dehiscence defects in groups Z1_D and T_D showed no further bone loss at 6 weeks compared to 2 weeks. CONCLUSIONS: The modified surface of Z1 demonstrated higher BIC values than the surface of Z2. There were minimal differences in the mucosal margin between 2 and 6 weeks in the presence of a dehiscence defect. The present model can serve as a useful tool for studying peri-implant dehiscence defects at the hard and soft tissue levels.

10-year randomized trial (RCT) of zirconia-ceramic and metal-ceramic fixed dental prostheses.

OBJECTIVES: To monitor zirconia-ceramic and metal-ceramic posterior FDPs with respect to survival and technical/biological complication rates. MATERIALS AND METHODS: Fifty-eight patients received 76 3- to 5-unit posterior FDPs. The sites were randomly assigned to 40 zirconia-based (ZC) and 36 metal-based (MC) FDPs. FDPs were examined at baseline (cementation), at 6 months, at 1 year and then yearly up to 10 years. Technical outcomes were assessed using modified United States Public Health Service (USPHS) criteria. Biologic outcomes included probing depth, plaque, bleeding on probing and tooth vitality. Statistical analysis was performed applying Kaplan-Meier (KM) estimation, log-rank, Mann-Whitney and Fisher exact test. RESULTS: During the 10-year follow-up thirteen patients (17 FDPs) dropped out and 6 FDPs in 6 patients (5 ZC,1 MC) were considered catastrophic failures for technical and/or biological reasons. Forty-four patients with 53 FDPs (29 ZC, 24 MC) were available for examination. The median observation period was 10.3 years (ZC) and 10.0 years (MC). The 10-year KM survival estimate of ZC FDPs was 91.3% (95%CI:69.5;97.8) and 100% of MC FDPs. Minor chipping of the veneering ceramic and occlusal wear were found to a similar extent at ZC and MC FDPs. ZC FDPs demonstrated a significantly higher rate of framework fracture, de-bonding, major fractures of the veneering ceramic and poor marginal adaption. Biological outcomes were similar in both groups and between abutment and control teeth. CONCLUSION: At 10 years, ZC and MC posterior FDPs resulted in similar outcomes for the majority of the outcome measures (p > 0.05).

Comparison of Fixed Dental Prostheses with Zirconia and Metal Frameworks: Five-Year Results of a Randomized Controlled Clinical Trial.

PURPOSE: The aim of this study was to test whether posterior zirconia-ceramic (ZC) and metal-ceramic (MC) fixed dental prostheses (FDPs) exhibit similar survival and technical/biologic complication rates. MATERIALS AND METHODS: A total of 58 patients in need of 76 posterior FDPs were randomly assigned to receive 40 ZC and 36 MC FDPs. The restorations were examined at baseline (cementation) and yearly for 5 years. Technical and biologic outcomes were compared. The independent treatment groups were compared with nonparametric Mann-Whitney test for metric variables and with Fisher exact test for categoric data. RESULTS: A total of 52 patients with 40 ZC and 29 MC FDPs were examined at 5 years. No FDP failed during the 5 years; 2 ZC FDPs failed at 65.4 and 73.3 months. Debonding occurred at 3 ZC FDPs. Technical outcomes (modified US Public Health Service criteria) and general periodontal parameters did not show significant differences between ZC and MC FDPs. CONCLUSION: ZC FDPs exhibited similar outcomes to MC FDPs based on 5-year survival estimates. The majority of technical and biologic outcome measures were not significantly different.

Eleven-Year Follow-Up of a Prospective Study of Zirconia Implant Abutments Supporting Single All-Ceramic Crowns in Anterior and Premolar Regions.

BACKGROUND: Clinical studies on zirconia abutments report very good survival rates and biological and technical results, but few have an observation period of more than 5 years. PURPOSE: The aim of this study was to assess the long-term performance of customized zirconia implant abutments supporting all-ceramic crowns. MATERIALS AND METHODS: Twenty-seven patients receiving 54 single implants were included (25 incisors, 14 canines, 15 premolars in both jaws). Yttria-stabilized zirconia abutments were screwed to the implants with a defined torque. All-ceramic crowns were adhesively cemented onto the abutments. The implants, abutments, and crowns were clinically and radiographically examined after 11 years of use. Modified United States Public Health Service (USPHS) criteria were used to assess technical outcomes: fracture of abutment/crown framework/veneering ceramic, loosening of abutment screw/crown, marginal adaptation, anatomical form, occlusal wear, and abutment fit. The biological parameters were pocket probing depth, plaque control record, bleeding on probing, papilla index, and gingival/mucosal recession at implants and neighboring natural teeth. The cumulative success rate of abutments and crowns was calculated by the Kaplan-Meier method. The results of the USPHS criteria were analyzed descriptively. RESULTS: Sixteen patients with 31 zirconia abutments were examined at 11.3 (±0.9) years after implantation. No abutment or crown was lost. The cumulative success rate was 96.3% for abutments and 90.7% for crowns. Two abutment screws loosened, and three crowns exhibited minor chipping. There were no biological complications. CONCLUSIONS: Customized zirconia single implant abutments exhibited excellent long-term outcomes in anterior and premolar regions.

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.

Retrospective clinical study of single-retainer cantilever anterior and posterior glass-ceramic resin-bonded fixed dental prostheses at a mean follow-up of 6 years.

PURPOSE: To retrospectively evaluate the 6-year survival rates and technical/ biologic complication rates of single-retainer glass-ceramic resin-bonded fixed dental prostheses (RBFDPs). MATERIALS AND METHODS: Forty patients with 49 anterior/posterior glass-ceramic RBFDPs were included. The RBFDPs replaced 11 maxillary/mandibular central incisors, 18 lateral incisors, 18 premolars, and 2 molars. Patients willing to participate were clinically and radiologically examined. The technical outcome was assessed 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. Tooth vitality and postoperative sensitivity were tested. The following biologic parameters were assessed at test and control teeth: probing pocket depth, gingival recession, attachment loss, bleeding on probing, furcation involvement, and periodontal mobility. Statistical analysis was performed with exact 95% confidence intervals to relative frequencies and the paired t test. RESULTS: Twenty-eight patients with 35 RBFDPs participated. The mean follow-up of the RBFDPs was 6 years. Twelve patients with 14 RBFDPs were not willing to participate or not available. No catastrophic failures occurred. The 6-year survival rate of the examined RBFDPs was 100%. No debonding was recorded. Chipping of the ceramic was found in 5.7% of the RBFDPs. Biologic outcomes were similar at test and control teeth. CONCLUSION: Glass-ceramic RBFDPs exhibited promising clinical outcomes in both anterior and posterior regions.

Novel ceria-stabilized tetragonal zirconia/alumina nanocomposite as framework material for posterior fixed dental prostheses: preliminary results of a prospective case series at 1 year of function.

OBJECTIVE: To examine the clinical performance of veneered ceria-stabilized tetragonal zirconia/alumina-nanocomposite (Ce-TZP/A-nanocomposite) frameworks for three-unit fixed dental prostheses (FDPs). METHOD AND MATERIALS: Eight patients in need of one FDP replacing one premolar or molar were included in this case series. Eight Ce-TZP/A-nanocomposite FDP frameworks were fabricated with a CAD/CAM system (Hint-Els) and veneered with a zirconia veneering ceramic (Vintage ZR, Shofu). The FDPs were cemented with resin cement (baseline) and were evaluated at baseline; 2 weeks; and 3, 6, and 12 months after cementation. For the technical evaluation, the USPHS criteria were used. The biologic outcome was judged by comparing the plaque control record (PCR), bleeding on probing (BOP), and probing pocket depth (PPD) of the abutment teeth (test) and untreated contralateral teeth (control). Radiographs were made at baseline and at 6 and 12 months of follow-up. The data were descriptively analyzed. RESULTS: The mean observation period of the eight examined FDPs was 12.8 +/- 1.1 months. The survival rate of the FDPs was 100%. Furthermore, no technical or biologic complications were found. No differences of the mean (m) PCR (test: 0.1 +/- 0.1, control: 0.2 +/- 0.2), mBOP (test: 0.2 +/- 0.2, control: 0.1 +/- 0.1), and mPPD (test: 2.6 +/- 0.8, control: 2.6 +/- 0.6) were found between test and control teeth. CONCLUSIONS: Ce-TZP/A nanocomposite was found to be a reliable framework material at 1 year of function. Longer observation periods and randomized controlled clinical trials including more patients are needed to validate these findings.

In vitro study of the influence of the type of connection on the fracture load of zirconia abutments with internal and external implant-abutment connections.

PURPOSE: To determine whether zirconia abutments with an internal connection exhibit similar fracture load as zirconia abutments with an external connection. MATERIALS AND METHODS: The following zirconia abutments were divided into four groups of 20 each: StraumannCARES abutments on Straumann implants (group A), Procera abutments on Branemark implants (group B), Procera abutments on NobelReplace implants (group C), and Zirabut SynOcta prototype abutments on Straumann implants (group D). The abutments were fixed on their respective implants either internally via a secondary abutment (A) or a metallic coupling (C) (two-piece) or directly externally (B) and internally (D) (one-piece). In each group, 10 abutments were left unrestored (A1 to D1). Ten received glass-ceramic crowns (A2 to D2). Static loading was performed according to the ISO norm 14801 until failure. The bending moment was calculated for comparison of the groups and subjected to statistical analysis (Student t test). RESULTS: The mean bending moments of the unrestored abutments were 371.5 +/- 142.3 Ncm (A1), 276.5 +/- 47.6 Ncm (B1), 434.9 +/- 124.8 Ncm (C1), and 182.5 +/- 136.5 Ncm (D1). Two-piece internally connected abutments exhibited higher bending moments than one-piece internally (C1 versus D1 P = .003, A1 versus D1 P = .03) or externally (C1 versus B1 P = .004) connected abutments. The groups with restorations did not show different bending moments than those without restorations. The mean bending moments of the restored abutments were 283.3 +/- 44.8 Ncm (A2), 291.5 +/- 31.7 Ncm (B2), 351.5 +/- 58 Ncm (C2), and 184.3 +/- 77.7 Ncm (D2). Group C2 exhibited the highest bending moment (P < .05). Internally connected one-piece abutments (D2) were weaker than all other groups (D2 versus A2 P = .002; D2 versus B2 P = .001; D2 versus C2 P = .0003). CONCLUSIONS: The type of connection significantly influenced the strength of zirconia abutments. Superior strength was achieved by means of internal connection via a secondary metallic component.

Misfit of suprastructures on implants processed by electrical discharge machining or the Cresco method.

OBJECTIVE: To assess the accuracy of fit of frameworks on implants processed with electrical discharge machining (EDM) or the Cresco technique (Astra Tech). METHOD AND MATERIALS: On 12 identical master casts with implants at positions 9(21), 11(23), and 13(25), high-gold alloy frameworks were produced by standard casting procedure. Six frameworks were used for the Cresco technique (group CRE) by employing specific fixed partial denture supports. The remaining 6 frameworks were cast with prefabricated gold copings and served as control. The finished frameworks were screwed onto implant 25 of the corresponding master cast. Dimensions of the marginal gaps were measured at 4 locations on each implant under the scanning electron microscope, applying the replica technique. Subsequently, the control group was processed by EDM (SAE EDM 2000) (group EDM) and analyzed alike. Statistical analysis of the results was performed with Kruskal-Wallis and Mann-Whitney U tests. RESULTS: The mean marginal gaps were measured as follows (CRE/EDM/control): position 25: 0.0 microm/1.0 +/- 1.6 microm/1.5 +/- 2.1 microm; position 23: 5.2 +/- 5.6 microm/18.7 +/- 29.3 microm/23.6 +/- 30.7 microm; and position 21: 36.0 +/- 21.6 microm/40.7 +/- 31.0 microm/46.0 +/- 41.1 microm. The only statistically significant difference was found at location 23 between group CRE on one side and both group EDM and control on the other side. The strong increase of misfit for group CRE from location 23 to location 21 indicates that laser welding is the crucial parameter in this technique. CONCLUSION: The Cresco technique has a potential to reduce the marginal gap between implants and suprastructures.

Randomized-controlled clinical trial of customized zirconia and titanium implant abutments for single-tooth implants in canine and posterior regions: 3-year results.

OBJECTIVES: The aim was to test whether or not zirconia abutments exhibit the same survival and technical/biological outcome as titanium abutments. MATERIAL AND METHODS: Twenty-two patients receiving 40 single-tooth implants in canine and posterior regions were included. The implant sites were randomly assigned to 20 zirconia and 20 titanium abutments. All-ceramic and metal-ceramic crowns were fabricated. At baseline, 6, 12 and 36 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque control record (PCR) and bleeding on probing (BOP) were assessed at abutments (test) and analogous contralateral teeth (control). Standardized radiographs of the implants were made and the bone level (BL) was measured referring to the implant shoulder on mesial (mBL) and distal sides (dBL). The difference of color (DeltaE) of the peri-implant mucosa and the gingiva of control teeth was assessed with a spectrophotometer. The data were statistically analyzed with Mann-Whitney Rank and Student's unpaired t-tests. RESULTS: Eighteen patients with 18 zirconia and 10 titanium abutments were examined at a mean follow-up of 36 months (range 31.5-53.3 months). No fracture of an abutment or loss of a reconstruction was found. Hence, both exhibited 100% survival. At two metal-ceramic crowns supported by titanium abutments chipping of the veneering ceramic occurred. No difference of the biological outcome of zirconia and titanium abutments was observed: PPD (meanPPD(ZrO(2)) 3.2 +/- 1 mm, mPPD(Ti) 3.4 +/- 0.5 mm), PCR (mPCR(ZrO(2)) 0.1 +/- 0.2, mPCR(Ti) 0.1 +/- 0.2) and BOP (mBOP(ZrO(2)) 0.4 +/- 0.4, mBOP(Ti) 0.2 +/- 0.3). Furthermore, the BL was similar at implants supporting zirconia and titanium abutments (mBL(ZrO(2)) 1.7 +/- 1, dBL(ZrO(2)) 1.6 +/- 1; mBL(Ti) 2 +/- 1, dBL(Ti) 2.1 +/- 1). Both, zirconia and titanium abutments induced a similar amount of discoloration of the mucosa compared with the gingiva at natural teeth (DeltaE(ZrO(2)) 9.3 +/- 3.8, DeltaE(Ti) 6.8 +/- 3.8). CONCLUSIONS: At 3 years, zirconia and titanium abutments exhibited same survival and technical, biological and esthetical outcomes.

Randomized controlled clinical trial of customized zirconia and titanium implant abutments for canine and posterior single-tooth implant reconstructions: preliminary results at 1 year of function.

OBJECTIVES: The aim of this study was to test whether or not customized zirconia abutments exhibit the same survival rates in canine and posterior regions as titanium abutments, and to compare the esthetic result of the two abutment types. MATERIAL AND METHODS: Twenty-two patients with 40 implants in posterior regions were included and the implant sites were randomly assigned to 20 customized zirconia and 20 customized titanium abutments. All-ceramic (AC) and metal-ceramic (MC) crowns were fabricated. In all except two cases, the crowns were cemented on the abutments using resin or glass-ionomer cements. Two zirconia reconstructions were screw retained. At baseline, 6 and 12 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque (Pl) and bleeding on probing (BOP) were assessed and compared with natural control teeth. Furthermore, the difference of color (DeltaE) of the peri-implant mucosa and the gingiva of control teeth was evaluated by means of a spectrophotometer (Spectroshade). The data were analyzed with Student's unpaired t-test, ANOVA and regression analyses. RESULTS: Twenty patients with 19 zirconia and 12 titanium abutments were examined at a mean follow-up of 12.6+/-2.7 months. The survival rate for reconstructions and abutments was 100%. No technical or biological problems were found at the test and control sites. Two chippings (16.7%) occurred at crowns supported by titanium abutments. No difference was found regarding PPD (meanPPD(ZrO2) 3.4+/-0.7 mm, mPPD(Ti) 3.3+/-0.6 mm), Pl (mPl(ZrO2) 0.2+/-0.3, mPl(Ti) 0.1+/-1.8) and BOP (mBOP(ZrO2) 60+/-30%, mBOP(Ti) 30+/-40%) between the two groups. Both crowns on zirconia and titanium abutments induced a similar amount of discoloration of the soft tissue compared with the gingiva at natural teeth (DeltaE(ZrO2) 8.1+/-3.9, DeltaE(Ti) 7.8+/-4.3). CONCLUSIONS: At 1 year, zirconia abutments exhibited the same survival and a similar esthetic outcome as titanium abutments.

Five-year clinical results of zirconia frameworks for posterior fixed partial dentures.

PURPOSE: The aim of this prospective clinical cohort study was to determine the success rate of 3- to 5-unit zirconia frameworks for posterior fixed partial dentures (FPDs) after 5 years of clinical observation. MATERIALS AND METHODS: Forty-five patients who needed at least 1 FPD to replace 1 to 3 posterior teeth were included in the study. Fifty-seven 3- to 5-unit FPDs with zirconia frameworks were cemented with 1 of 2 resin cements (Variolink or Panavia TC). The following parameters were evaluated at baseline, after 6 months, and 1 to 5 years after cementation at test (abutments) and control (contralateral) teeth: probing pocket depth, probing attachment level, Plaque Index, bleeding on probing, and tooth vitality. Intraoral radiographs of the FPDs were taken. Statistical analysis was performed using descriptive statistics, Kaplan-Meier survival analysis, and the McNemar test. RESULTS: Twenty-seven patients with 33 zirconia FPDs were examined after a mean observation period of 53.4 +/- 13 months. Eleven patients with 17 FPDs were lost to follow-up. After the 3-year recall visit, 7 FPDs in 7 patients were replaced because they were not clinically acceptable due to biologic or technical complications. After 5 years of clinical observation, 12 FPDs in 12 patients had to be replaced. One 5-unit FPD fractured as a result of trauma after 38 months. The success rate of the zirconia frameworks was 97.8%; however, the survival rate was 73.9% due to other complications. Secondary caries was found in 21.7% of the FPDs, and chipping of the veneering ceramic in 15.2%. There were no significant differences between the periodontal parameters of the test and control teeth. CONCLUSIONS: Zirconia offers sufficient stability as a framework material for 3- and 4-unit posterior FPDs. The fit of the frameworks and veneering ceramics, however, should be improved.

Clinical study of the color stability of veneering ceramics for zirconia frameworks.

PURPOSE: The purpose of this study was to compare 3 veneering ceramics for zirconia frameworks regarding color stability and predictability of the esthetic result. MATERIALS AND METHODS: Six patients with 1 maxillary central incisor to be restored were enrolled in the study. The contralateral incisor had to be nonrestored and vital to serve as a reference tooth. For each patient, 4 single crowns with zirconia frameworks were fabricated. Three veneering ceramics were assessed and masked to eliminate bias. Choice of the veneering ceramics was done at random. The veneering was performed by 4 dental technicians. Three veneering ceramics were compared: ceramic A (Initial, GC), ceramic B (Triceram, Esprident), and ceramic C (Cercon Ceram S, DeguDent). The color of the crowns and reference teeth was captured using spectrophotometric analysis (SpectroShade, MHT), and the color difference (deltaE) was calculated (objective method). In addition, the crowns and reference teeth were compared subjectively by 11 observers blind to the ceramic used for veneering. Statistical analysis was performed with analysis of variance (ANOVA). RESULTS: Regardless of the veneering ceramic used, all crowns showed a high color deviation from the reference teeth when applying the objective analysis (deltaE(A) 6.8 +/- 2.5, deltaE(B) 5.6 +/- 1.2, deltaE(C) 5.7 +/- 2.1). In addition, no significant differences were found between the deltaE of crowns and teeth for the 3 ceramics. In the framework-supported area, ceramic B showed a significantly lower difference in value (deltaL) compared to the reference teeth than the other 2 ceramics (deltaL(A) 4.9 +/- 2.3, deltaL(B) 1.1 +/- 2.1, deltaL(C) 4.1 +/- 1.5; P < .01 ANOVA). When performing the subjective analysis, ceramic B was chosen as the best match by a majority of observers (> 60%) in 4 of 6 patients. CONCLUSIONS: All 3 ceramics met the esthetic demands only to a limited extent. Ceramic B allowed for the most predictable result in terms of color stability.