Soft-tissue dimensional change following guided bone regeneration on peri-implant defects using soft-type block or particulate bone substitutes: 1-year outcomes of a randomized controlled clinical trial.

AIM: To compare the peri-implant soft-tissue dimensional changes following guided bone regeneration between particulate (particle group) and collagenated soft-block-type (block group) biphasic calcium phosphate (BCP). MATERIALS AND METHODS: This study investigated 35 subjects: 18 in the particle group and 17 in the block group. Cone-beam computed tomography obtained at 6 months post surgery and optical impressions taken periodically (before surgery, 6 months post surgery, and 1 year post surgery) were superimposed. The ridge contour changes over time and the peri-implant mucosal thicknesses were measured diagonally and horizontally, and analysed statistically. RESULTS: The increases in diagonal (1.12 ± 0.78 mm) and horizontal (2.79 ± 1.90 mm) ridge contour of the block group were significantly higher than those in the particle group during the first 6 months (p < .05); however, the contour hardly changed thereafter (diagonal: 0.07 ± 0.75 mm; horizontal: -0.34 ± 1.26 mm), resulting in the 1-year contour changes similar between the two groups. Regardless of the type of BCP, the ridge contour increased significantly over 1 year when the dehiscence defect had a contained configuration (p < .05). CONCLUSIONS: The increase in soft-tissue dimensions for 1 year was similar between the two groups. The mucosal contour increase was larger when the surgery was conducted in a more contained defect, and this was not influenced by the type of BCP.

Randomized controlled clinical trial comparing guided bone regeneration of peri-implant defects with soft-type block versus particulate bone substitutes: Six-month results of hard-tissue changes.

AIM: To test whether soft-type block bone substitute used for guided bone regeneration (GBR) of peri-implant defects leads to a different dimension of the augmented hard tissue than particulate bone substitute. MATERIALS AND METHODS: In 40 patients, 40 two-piece dental implants were placed >2 months after tooth extraction. Following random allocation, 20 peri-implant bone dehiscences were grafted with a soft-type block made of synthetic biphasic calcium phosphate (BCP) + collagen and 20 bone dehiscences with particulate BCP. All the sites were covered with a collagen membrane stabilized with titanium pins. Immediately after wound closure and after 6 months, the horizontal dimension (HD) of the augmented hard tissue was measured at the level of implant shoulder using cone beam computed tomography. During re-entry at 6 months, the defect fill was clinically assessed. RESULTS: At 6 months, the median HD measured 1.15 mm (mean: 1.31 mm) in the soft-block group and 0.93 mm (mean: 1.05 mm) in the particulate group (p = .6). At 6 months, 7.1% of contained defects and 61.9% of non-contained defects showed an incomplete vertical defect fill. CONCLUSIONS: Soft-type block of BCP + collagen used for GBR of peri-implant defects did not differ from particulate BCP regarding the dimension of the augmented hard tissue after 6 months of healing.

Effect of collagen membrane and of bone substitute on lateral bone augmentation with titanium mesh: An experimental in vivo study.

AIM: The aim of this study was to identify the additional effects of collagen membrane (CM) and of synthetic bone substitute (BS) on lateral bone augmentation of chronic peri-implant defect with titanium mesh (TM). MATERIALS AND METHODS: Atrophic alveolar ridge was induced in six canine mandibles, and 5 peri-implant defects were achieved in each hemi-mandible. Bone augmentation was attempted using the following randomly allocated modalities: (1) Control: no treatment, (2) TM only group: blood clot covered by TM, (3) TM+BS group: BS covered by TM, (4) TM+CM group: blood clot covered by TM and CM, and (5) TM+BS+CM group: BS covered by TM and CM. After 16 weeks of submerged healing, micro-CT and histomorphometric analyses were performed. RESULTS: TM exposure occurred in one case in the TM only group, one case in the TM+CM group, and two cases in the TM+BS+CM group. Histologically, pseudo-periosteum was observed along the inner and outer surfaces of TM, and the directions of the collagen fiber within the pseudo-periosteum differed according to the additional use of CM. In general, the TM only group rendered higher values in vertical defect fill and dimension of the augmented hard tissue in comparison with the other treatment groups. CONCLUSIONS: Due to the small sample size, this pilot study remains inconclusive. Within the limitations of the study, the use of CM and/or BS did not appear to have an additional benefit on lateral bone augmentation of peri-implant defect with TM.

Effectiveness of xenogeneic and synthetic bone-block substitute materials with/without recombinant human bone morphogenetic protein-2: A preclinical study using a rabbit calvarium model.

AIM: To investigate new bone (NB) formation by using bone-block substitute materials with/without recombinant human bone morphogenetic protein-2 (rhBMP-2). MATERIALS AND METHODS: Three synthetic bone-block substitute materials [biphasic calcium phosphate (BCP); nanostructured hydroxyapatite (NH); 3D-printed tricalcium phosphate/hydroxyapatite (3DP)] and one xenogeneic deproteinized bovine bone mineral (DBBM) block substitute were affixed to rabbit calvarium using osteosynthesis screws, either with rhBMP-2 (n = 12) or without rhBMP-2 (n = 16). At 2 or 12 weeks (n = 6 with rhBMP-2 and n = 8 without rhBMP-2 for each week), histologic, histomorphometric and microcomputed tomography analyses were performed. RESULTS: The application of rhBMP-2 increased NB formation in all experimental groups at both weeks. DBBM resulted in a greater area of NB compared with synthetic blocks either with or without rhBMP-2 at 2 weeks (2.8 ± 0.9 vs. 1.4 ± 0.5-1.9 ± 1.4 mm2 ; 1.4 ± 1.0 vs. 0.6 ± 0.3-0.9 ± 0.5 mm2 ) and without rhBMP-2 at 12 weeks (3.0 ± 0.8 vs. 1.7 ± 0.7-2.6 ± 1.5 mm2 ) (p > 0.05). NB formation did not differ significantly for DBBM and the three types of synthetic block with rhBMP-2 at 12 weeks (4.5 ± 2.0 vs. 3.8 ± 0.7-5.1 ± 1.1 mm2 ; p > 0.05). CONCLUSIONS: rhBMP-2 enhanced NB in all blocks. DBBM blocks yielded more NB than synthetic blocks without rhBMP-2. The application of rhBMP-2 appears to compensate for differences in late healing.

Trueness of intraoral scanners in digitizing specific locations at the margin and intaglio surfaces of intracoronal preparations.

STATEMENT OF PROBLEM: Studies evaluating the trueness of intraoral scanners (IOSs) at anatomic locations within an intracoronal preparation are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the trueness of digital scans obtained by IOSs at the margin and intaglio surfaces of intracoronal preparations. MATERIAL AND METHODS: Six IOSs (CEREC Omnicam, E4D, FastScan, iTero, TRIOS, Zfx IntraScan) were used to obtain digital scans of various intracoronal preparations. Standard tessellation language (STL) data sets obtained from a reference scanner and each IOS were superimposed, and the deviation of the digital casts was assessed at multiple measuring points along the margin and intaglio surfaces of each preparation. The Kruskal-Wallis test and multiple Mann-Whitney tests were used to detect differences in trueness (α=.05). RESULTS: The overall median trueness values were lowest for TRIOS (23.9 µm), followed by Zfx IntraScan (24.6 µm), iTero (25.4 µm), FastScan (26.1 µm), CEREC Omnicam (26.9 µm), and E4D (77.5 µm). The greatest deviation was generally observed at the line angles between the preparation surfaces. The axiogingival line angle was the most error-prone location in the cavity preparations. An increased tendency to produce a more accurate impression was observed when the cavity had a greater width and more divergent walls. CONCLUSIONS: The trueness of digital scans was influenced by the type of IOS and the location within a prepared cavity. The trueness decreased at the line angles between the preparation surfaces, particularly at the axiogingival line angle. Among the tested IOSs, E4D produced the least accurate digital scans.

Prosthetic outcomes and clinical performance of CAD-CAM monolithic zirconia versus porcelain-fused-to-metal implant crowns in the molar region: 1-year results of a RCT.

OBJECTIVE: To investigate the clinical performance of monolithic zirconia implant crowns as compared to porcelain-fused-to-metal (PFM) implant crowns. MATERIALS AND METHODS: Seventy-six healthy patients received reduced diameter implants in the molar region. Following random allocation, either a monolithic zirconia crown (Mono-ZrO2 ) or a (PFM) was inserted. Crown and implant survival rates, modified USPHS criteria, clinical measurements, and interproximal marginal bone level (MBL) were assessed at crown delivery (baseline, BL) and at the 1-year follow-up (1y-FU). Data were analyzed descriptively. Fisher's exact test and Wilcoxon rank sum test were applied for statistical analysis. The level of statistical significance was set at p < .05. RESULTS: Thirty-nine Mono-ZrO2 and 37 PFM crowns were delivered. At the 1y-FU, one crown in each group was lost due to loss of the implant. Technical complications occurred in the PFM group and were limited to four minor ceramic chippings resulting in a total technical complication rate of 11.1% (p = .024). Anatomical form and color match compared to the adjacent dentition were rated significantly inferior for the Mono-ZrO2 crowns. Patient satisfaction was high in both groups at BL (34 Mono-ZrO2 34 PFM) and at 1y-FU (36 Mono-ZrO2 31 PFM). No significant differences between the groups were detected with respect to the change in MBL and to the soft tissue parameters. CONCLUSIONS: Monolithic zirconia crowns are a similarly successful alternative option to PFM crowns for restoring single implants in the posterior area.

Hard tissue changes after guided bone regeneration of peri-implant defects comparing block versus particulate bone substitutes: 6-month results of a randomized controlled clinical trial.

OBJECTIVES: To test whether block bone substitute used for guided bone regeneration (GBR) of peri-implant defects leads to different thickness of the augmented hard tissue than particulate bone substitute. MATERIAL AND METHODS: In 24 patients, 24 two-piece dental implants were placed >4 months after tooth extraction. Following random allocation, 12 peri-implant bone dehiscences were grafted with an individually shaped block of deproteinized bovine-derived bone mineral (DBBM) and 12 bone dehiscences with particulate DBBM. All the sites were covered with a collagen membrane stabilized with resorbable pins. Immediately after wound closure and after 6 months, the horizontal thickness (HT) of the augmented hard tissue was measured at the level of implant shoulder using cone beam-computed tomography. RESULTS: After wound closure, the median HT measured 3.35 mm (mean: 3.38) in the block group and 2.85 mm (mean: 2.73) in the particulate group. At 6 months, the median HT decreased to 2.90 mm (mean: 2.71) in the block group and to 0.2 mm (mean: 0.52) in the particulate group. This difference was statistically significant (p < .001). CONCLUSIONS: Block bone substitute used for GBR of peri-implant defects was superior to particulate bone substitute regarding the dimension of the augmented hard tissue after 6 months of healing.

Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part I: Time efficiency of complete-arch digital scans versus conventional impressions.

STATEMENT OF PROBLEM: Clinical trials are needed to evaluate digital and conventional technologies for providing fixed partial dentures. PURPOSE: The purpose of the first part of this clinical study was to test whether complete-arch digital scans were similar to or better than complete-arch conventional impressions regarding time efficiency and participant and clinician perceptions. MATERIAL AND METHODS: Ten participants in need of a posterior tooth-supported 3-unit fixed partial denture were included. Three intraoral digital scanners and subsequent workflows (Lava C.O.S.; 3M [Lava], iTero; Align Technology Inc [iTero], Cerec Bluecam; Dentsply Sirona [Cerec]) were compared with the conventional impression method using polyether (Permadyne; 3M) and the conventional workflow. A computer-generated randomization list was used to determine the sequence of the tested impression procedures for each participant. The time needed for the impression procedures, including the occlusal registration, was assessed. In addition, the participant and clinician perceptions of the comfort and difficulty of the impression were rated by means of visual analog scales. Data were analyzed with the nonparametric paired Wilcoxon test together with an appropriate Bonferroni correction to detect differences among the impression systems (α=.05). RESULTS: The total time for the complete-arch impressions, including the preparation (powdering) and the occlusal registration, was shorter for the conventional impression than for the digital scans (Lava 1091 ±523 seconds, iTero 1313 ±418 seconds, Cerec 1702 ±558 seconds, conventional 658 ±181 seconds). The difference was statistically significant for 2 of the 3 digital scanners (iTero P=.001, Cerec P<.001). The clinicians preferred the conventional impression to the digital scans. Of the scanning systems, the system without the need for powdering was preferred to the systems with powdering. No impression method was clearly preferred over others by the participants. CONCLUSIONS: For complete-arch impressions, the conventional impression procedures were objectively less time consuming and subjectively preferred by both clinicians and participants over digital scan procedures.

Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic fixed partial dentures. Part III: Marginal and internal fit.

STATEMENT OF PROBLEM: Trials comparing the overall performances of digital and conventional workflows in restorative dentistry are lacking. PURPOSE: The purpose of the third part of this clinical study was to test whether the fit of zirconia 3-unit frameworks for fixed partial dentures fabricated with fully digital workflows differed from that of metal frameworks fabricated with the conventional workflow. MATERIAL AND METHODS: In each of 10 participants, 4 fixed-partial-denture frameworks were fabricated for the same abutment teeth according to a randomly generated sequence. Digital workflows were applied for the fabrication of 3 zirconia frameworks with Lava, iTero, and Cerec infiniDent systems. The conventional workflow included a polyether impression, manual waxing, the lost-wax technique, and the casting of a metal framework. The discrepancies between the frameworks and the abutment teeth were registered using the replica technique with polyvinyl siloxane. The dimensions of the marginal discrepancy (Discrepancymarginal) and the internal discrepancy in 4 different regions of interest (Discrepancyshoulder, Discrepancyaxial, Discrepancycusp, and Discrepancyocclusal) were assessed using a light microscope. Post hoc t tests with Bonferroni correction were applied to detect differences (α=.05). RESULTS: Discrepancyshoulder was 96.1 ±61.7 µm for the iTero, 106.9 ±96.0 µm for the Lava, 112.2 ±76.7 µm for the Cerec infiniDent, and 126.5 ±91.0 µm for the conventional workflow. The difference between the iTero and the conventional workflow was statistically significant (P=.029). Discrepancyocclusal was 153.5 ±66.8 µm for the iTero, 203.3 ±127.9 µm for the Lava, 179.7 ±63.1 µm for the Cerec infiniDent, and 148.8 ±66.8 µm for the conventional workflow. Discrepancyocclusal was significantly lower for the conventional workflow than for the Lava and the Cerec infindent workflows (P<.01). The iTero resulted in significantly lower values of Discrepancyocclusal than the Lava and the Cerec infiniDent workflows (P<.01). CONCLUSIONS: In terms of framework fit in the region of the shoulder, digitally fabricated zirconia 3-unit frameworks presented similar or better fit than the conventionally fabricated metal frameworks. In the occlusal regions, the conventionally fabricated metal frameworks achieved a more favorable fit than the CAD-CAM zirconia frameworks.

Randomized controlled clinical trial of digital and conventional workflows for the fabrication of zirconia-ceramic posterior fixed partial dentures. Part II: Time efficiency of CAD-CAM versus conventional laboratory procedures.

STATEMENT OF PROBLEM: Clinical trials are needed to evaluate the digital and conventional fabrication technology for providing fixed partial dentures (FPDs). PURPOSE: The purpose of the second part of this clinical study was to compare the laboratory production time for tooth-supported, 3-unit FPDs by means of computer-aided design and computer-aided manufacturing (CAD-CAM) systems and a conventional workflow. In addition, the quality of the 3-unit framework of each treatment group was evaluated clinically. MATERIAL AND METHODS: For each of 10 participants, a 3-unit FPD was fabricated. Zirconia was used as the framework material in the CAD-CAM systems and included Lava C.O.S. CAD software (3M) and centralized CAM (group L); CARES CAD software (Institut Straumann AG) and centralized CAM (group iT); and CEREC Connect CAD software (Dentsply Sirona) and centralized CAM (group C). The noble metal framework in the conventional workflow (group K) was fabricated by means of the traditional lost-wax technique. All frameworks were evaluated clinically before veneering. The time for the fabrication of the cast, the 3-unit framework, and the veneering process was recorded. In addition, chairside time during the clinical appointment for the evaluation of the framework was recorded. The paired Wilcoxon test together with appropriate Bonferroni correction was applied to detect differences among treatment groups (α=.05). RESULTS: The total effective working time (mean ±standard deviation) for the dental technician was 220 ±29 minutes in group L, 217 ±23 minutes in group iT, 262 ±22 minutes in group C, and 370 ±34 minutes in group K. The dental technician spent significantly more time in the conventional workflow than in the digital workflow, independent of the CAD-CAM systems used (P<.001). CONCLUSIONS: Irrespective of the CAD-CAM system, the overall laboratory time for the dental technician was significantly less for a digital workflow than for the conventional workflow.

Assessment of peri-implant defects at titanium and zirconium dioxide implants by means of periapical radiographs and cone beam computed tomography: An in-vitro examination.

OBJECTIVE: To test the accuracy of measurement of interproximal peri-implant bone defects at titanium (Ti) and zirconium dioxide (ZrO2 ) implants by digital periapical radiography (PR) and cone beam computed tomography (CBCT). MATERIAL AND METHODS: A total of 18 models, each containing one Ti and one ZrO2 implant, were cast in dental stone. Six models each were allocated to following defect groups: A-no peri-implant defect, B-1 mm width defect, C-1.5 mm width defect. The defect width was measured with a digital sliding caliper. Subsequently, the models were scanned by means of PR and CBCT. Three examiners assessed the defect width on PR and CBCT. Wilcoxon signed-rank test and Wilcoxon rank sum test were applied to detect differences between imaging techniques and implant types. RESULTS: For PR, the deviation of the defect width measurement (mm) for groups A, B, and C amounted to 0.01 ± 0.03, -0.02 ± 0.06, and -0.00 ± 0.04 at Ti and 0.05 ± 0.02, 0.01 ± 0.03, and 0.09 ± 0.03 at ZrO2 implants. The corresponding values (mm) for CBCT reached 0.10 ± 0.11, 0.26 ± 0.05, and 0.24 ± 0.08 at Ti and 1.07 ± 0.06, 0.64 ± 0.37, and 0.54 ± 0.17 at ZrO2 implants. Except for Ti with defect A, measurements in PR were significantly more accurate in comparison to CBCT (p ≤ 0.05). Both methods generally yielded more accurate measurements for Ti than for ZrO2 . CONCLUSIONS: The assessment of interproximal peri-implant defect width at Ti and ZrO2 implants was more accurate in PR in comparison to CBCT. Measurements in CBCT always led to an overestimation of the defect width, reaching clinical relevance for ZrO2 implants.

Clinical and histologic evaluation of different approaches to gain keratinized tissue prior to implant placement in fully edentulous patients.

OBJECTIVES: This work aimed to investigate the effectiveness and predictability of different treatment modalities for gain of keratinized tissue (KT) in fully edentulous jaws prior to dental implant placement: apically positioned flap (APF), APF plus xenogeneic collagen matrix (XCM), and APF plus free gingival graft (FGG). MATERIALS AND METHODS: In fully edentulous patients with insufficient zones of KT at the prospective implant positions, four treatment modalities were performed in the lower jaw: APF, XCM, FGG, and an untreated control group (control). APF and XCM were applied in the first molar positions, FGG and control in the canine positions. Assessed outcomes up to 3 months post-surgery included changes in width of KT (over a 3-month period), histomorphometric analysis of harvested soft-tissue biopsies (at 3 months postoperatively), and patient-reported outcomes measures (PROMs). RESULTS: For the primary outcome, changes in KT width demonstrated an increase of 1.93 ± 1.6 mm (APF), whereas XCM and FGG showed an increase of 4.63 ± 1.25 mm and 3.64 ± 2.01, respectively. Histomorphometric analyses revealed a thickness of the epithelium ranging between 375 ± 122 µm (APF), 410 ± 116 µm (XCM), 336 ± 122 µm (FGG), and 413 ± 109 µm (control). All biopsies showed a regular muco-periosteal structure with a keratinized epithelium of comparable thickness in all groups. CONCLUSION: All three methods were suitable to increase the width of KT, although APF alone rendered roughly 50% less gain compared to XCM and FGG. CLINICAL RELEVANCE: The use of XCM in conjunction with an APF represents a valuable treatment option for the gain of keratinized tissue in edentulous sites.

Volumetric and linear changes at dental implants following grafting with volume-stable three-dimensional collagen matrices or autogenous connective tissue grafts: 6-month data.

OBJECTIVES: The objective of this study was to test whether or not soft tissue augmentation with a volume-stable collagen matrix (VCMX) leads to similar volume gain around dental implants compared to autogenous subepithelial connective tissue graft (SCTG). MATERIALS AND METHODS: In 12 adult beagle dogs, immediate implants were placed with simultaneous guided bone regeneration. After 25-45 weeks, soft tissue augmentation was randomly performed using VCMX, SCTG, or a sham-operated control. Impressions were taken pre-op and post-op (tissue augmentation) and again at sacrifice after healing periods of 4, 8, and 24 weeks. They were then digitized to allow for superimposition. Values of linear and volumetric changes were calculated. RESULTS: The median increase (pre-op to post-op) in buccal volume measured 0.92 mm for VCMX, 1.47 mm for SCTG, and 0.24 mm for SH. The values (pre-op to sacrifice) were - 0.25 mm for VCMX, 0.52 mm for SCTG, and - 0.06 mm for group SH. The median ridge width 2 mm below the crest measured - 0.26 mm for VCMX, 0.53 mm for SCTG, and - 0.15 mm for SH (pre-op to sacrifice). CONCLUSIONS: Volume augmentation using VCMX and SCTG resulted in an increase in ridge dimension (pre- to post-op). During the follow-up, the volume decreased in all three groups to a level close to the situation prior to surgery. CLINICAL RELEVANCE: Soft tissue volume augmentation around dental implants is usually performed using the patient's own tissue. This therapy is associated with an increased morbidity due to a second surgical site. Soft tissue volume at implant sites can be augmented using VCMX and SCTG. The gain on top of the ridge appears not to be stable during the follow-up in both groups.

Clinical quality and efficiency of monolithic glass ceramic crowns in the posterior area: digital compared with conventional workflows.

PURPOSE: The aim of this clinical study was to test whether or not digital workflows for the fabrication of crowns render different clinical outcomes from the conventional pathway with respect to (1) crown quality, and (2) time efficiency. MATERIAL AND METHODS: For each of the 10 patients in need of one tooth-supported crown, five monolithic crowns were produced out of lithium disilicate reinforced glass ceramic. Four different optical impression and associated computer-aided design/computer-aided manufacturing (CAD/CAM) systems were used for crown fabrication (digital workflows): (1) Lava C.O.S. scanner and Lava C.O.S. and CARES CAD software, centralized CAM (group L); (2) Cadent iTero scanner, CARES CAD software and centralized CAM (group iT); (3) Cerec Bluecam, Cerec Connect CAD software, followed by laboratory-based CAM (group CiL); and (4) centralized CAM (group CiD). The conventional crown (group K) was fabricated based on a conventional silicone impression followed by a conventional wax-up and heat press technique. The examiners were blinded and evaluated the crowns clinically at the bisque-bake stage (initial try-in), and subsequently after finalization by a dental technician (final try-in). For the assessment of crown quality, modified United States Public Health Service (USPHS) criteria were used. Treatment times were recorded for clinical evaluation and adjustment. The quality ratings were analyzed descriptively. For both the continuous and ordinal outcomes, the non-parametric paired Wilcoxon test was applied, together with an appropriate Bonferroni correction to evaluate the differences between treatment groups. The results of the statistical analysis were interpreted globally at the significance level P = 0.05. RESULTS: The clinical evaluation during the initial and final try-ins demonstrated similar clinical outcome measures for crowns generated with the four digital workflows and the conventional workflow. No statistically significant differences of crown quality in any state were found between groups (P > 0.005). The total clinical treatment times measured were: 456 ± 240 s for L; 655 ± 374 s for iT; 783 ± 403 s for CiL; 556 ± 285 s for CiD; and 833 ± 451 s for K. No statistically significant differences in treatment times were found between the groups (P > 0.05). CONCLUSIONS: Within the limitations of the present study, the monolithic ceramic crowns resulting from the four different CAD/CAM systems did not differ from the conventionally produced crowns with respect to the clinical quality rating and the treatment time efficiency.

Clinical and radiographic intra-subject comparison of implants placed with or without guided bone regeneration: 15-year results.

AIM: To test whether implants placed with simultaneous guided bone regeneration (GBR) differ from implants placed without GBR regarding survival rate, interproximal marginal bone level (MBL), and dimensions of buccal bone and mucosa. MATERIAL AND METHODS: Twenty-three patients treated 15 years earlier were included. Machined implants had been inserted following one of the two procedures: (i) with simultaneous GBR, which involved grafting with particulate deproteinized bovine bone mineral (DBBM), autogenous bone (AB), or a mixture of the two and defect covering with a native collagen membrane (CM) (GBR group) and (ii) standard implant placement without GBR (control group). One GBR and one control implant in each patient were selected for analysis. At 15 years, the dimensions of buccal bone and mucosa were measured with cone beam computed tomography. The interproximal MBL was evaluated at 5 and 15 years on periapical radiographs. RESULTS: The 15-year survival rate amounted to 95.6% for GBR implants and to 94.1% for control implants. At 15 years, interproximal MBL measured 1.44 ± 0.84 mm for the GBR group and 1.69 ± 0.84 mm for the control group. From the 5- to the 15-year examination, the loss of interproximal MBL reached 0.23 ± 0.70 mm for the GBR group and 0.28 ± 0.63 mm for the control group. At 15 years, buccal MBL measured 1.98 ± 0.98 mm for GBR implants and 2.19 ± 1.29 mm for control implants. None of these values reached statistical significant differences between the groups. In cases in which GBR involved grafting with DBBM, GBR implants achieved approximately 0.3-0.4 mm higher mean values in buccal bone dimensions and mucosal level in comparison to control implants. In contrast, when GBR was performed by grafting with AB without DBBM, implants rendered less favourable results in buccal bone and mucosa dimensions than the control implants. CONCLUSIONS: Implants placed with simultaneous GBR using particulate DBBM and/or AB in combination with CM did not significantly differ from implants completely placed into pristine bone with respect to 15-year implant survival, interproximal bone levels, and dimensions of buccal bone and mucosa. The machined-surface implants placed both into native bone and sites augmented by GBR exhibited stable interproximal bone levels.

Effect of ridge preservation for early implant placement - is there a need to remove the biomaterial?

AIM: To assess (i) bone regeneration around implants placed early in sites with or without ridge preservation and (ii) if the bone substitute material (DBBM-C) has to be removed at implant placement. MATERIALS AND METHODS: In eight beagle dogs, three sites were randomly assigned to ridge preservation (DBBM-C plus collagen matrix (CMX)) (two sites; RP) or spontaneous healing (1 site; SH). Four weeks later, in one of the RP sites, dental implants were placed without removing the DBBM-C (RP1), whereas in RP2 and SH sites all non-integrated DBBM-C and/or granulation tissue were removed before implant placement and concomitant GBR. Histomorphometric outcomes were assessed at 4 and 12 weeks. RESULTS: The median buccal fBIC (first bone-to-implant contact) was located more apical in groups RP1: 1.34 mm (0.09; 2.96) and RP2: 1.41 mm (0.54; 2.72) than in group SH: 0.79 mm (0.26; 1.50) (p = 0.452) at 4 weeks. At 12 weeks, median buccal fBIC values were for RP1: 0.88 mm (0.00; 2.33), for RP2: 0.16 mm (0.00; 1.33) and for SH: 0.00 mm (0.00; 0.98) (p = 0.362). BIC values increased over 12 weeks in all groups. CONCLUSIONS: Ridge preservation followed by early implant placement led to higher BIC values at 12 than at 4 weeks. There is no need to remove the biomaterial at implant placement to ensure osseointegration. No relevant differences were observed between the three groups for any outcome measure.

Soft tissue volume augmentation at dental implant sites using a volume stable three-dimensional collagen matrix - histological outcomes of a preclinical study.

AIM: The aim of this study was to test whether or not soft tissue augmentation with a collagen matrix (VCMX) leads to a similar increase in ridge width around dental implants compared to the use of an autogenous subepithelial connective tissue graft (SCTG). MATERIALS AND METHODS: In 12 dogs, immediate dental implants were placed with simultaneous guided bone regeneration. Three months later, soft tissue volume augmentation was performed by randomly allocating three treatment modalities to these sites [VCMX, SCTG, sham-operated group (control)]. Dogs were sacrificed at 1 (n = 4), 2 (n = 4) or 6 months (n = 4). Descriptive histology and histomorphometric measurements for soft tissue thickness were performed on non-decalcified sections. RESULTS: The horizontal soft tissue thickness was maximal at the most coronal level (alveolar crest) at 1 month (VCMX: 2.1 ± 1.6 mm; SCTG: 2.5 ± 1.7 mm; p = 0.877) and decreased until 6 months. At 6 months, the greatest mucosal thickness was at a level 3.5 mm below the crest (VCMX: 0.8 ± 0.3 mm; SCTG: 0.7 ± 0.2 mm) (p = 0.754). Control sites revealed no relevant soft tissue augmentation at any level and any time-point. Tissue integration for VCMX and SCTG were favourable with minimal inflammatory reactions. CONCLUSIONS: Soft tissue volume augmentation at implant sites was obtained to a similar extent using VCMX and SCTG up to 2 months. Thereafter, degradation and remodelling processes were enhanced leading to a minimal increase in soft tissue thickness at 6 months for VCMX and SCTG.

Randomized controlled clinical trial comparing one-piece and two-piece dental implants supporting fixed and removable dental prostheses: 4- to 6-year observations.

OBJECTIVES: To test whether or not a one- (S1) and a two-piece (S2) dental implant systems render the same biological, technical, and esthetic outcomes regarding implants and implant-supported reconstructions over an observation period of 4 to 6 years. MATERIALS AND METHODS: Sixty patients were randomly assigned to receive S1 or S2 implants. The implants were restored with either fixed or removable prostheses. The insertion of the final reconstruction was chosen as baseline. One-year and 4- to 6-year (FU-5) measurements included biological (e.g. marginal bone level, probing pocket depth, peri-implant mucositis, and peri-implantitis), technical (e.g. fracture or loosening of prosthetic screws, fracture or loosening of abutments, fracture of framework, and/or veneering ceramic (minor, major), loss of retention for cemented restorations), and esthetic parameters (visibility of the crown margin, shimmering of the implant through the mucosa, the level of the facial margo mucosae compared to the contralateral tooth or implant site and the modified papilla index) for implants and reconstructions. Survival and success rates of implants and reconstructions were calculated. Because of the asymmetric data distributions, nonparametric statistical methods were applied. RESULTS: The implant-based analysis revealed a cumulative implant survival rate of 97.9% (S1: 96.6%; S2: 98.9%) at FU-5. The median marginal bone level for group S1 changed from 0.51 mm at baseline to 0.49 mm at FU-5 and for group S2 from 1.02 mm to 1.35 mm (P < 0.001). Patient-level analyses demonstrated a frequency of peri-implant mucositis of 7.7% (S1) and 10.0% (S2) and for peri-implantitis of 7.7% (S1) and 13.3% (S2) at FU-5. The patient-based cumulative implant survival rate was 94.6% (S1: 92.3%; S2: 96.7%). The overall patient-based biological complication rate amounted to 15.4% (S1) and to 23.3% (S2) (P = 0.517), whereas the overall technical complication rates were 30.8% (S1) and 13.3% (S2) (P = 0.349). The prosthetic survival rates were 93.1% for S1 and 100% for S2 (P > 0.05). CONCLUSIONS: Both implant systems reveal high survival rates on the implant and prosthetic level. Apart from marginal bone-level changes, biological and technical outcomes did not reveal significant differences between the two implant systems.

Spectrophotometric and visual evaluation of peri-implant soft tissue color.

AIM: To spectrophotometrically and visually test whether the peri-implant mucosal color differs from the color of the natural gingiva. MATERIAL AND METHODS: Forty single implants in the incisor and premolar region of 40 patients were assessed 3-7 years after implant placement. The differences of the color components lightness, chroma along red-green axis, chroma along yellow-blue axis, and the total color difference ΔE between peri-implant mucosa and natural gingiva were measured with a spectrophotometer. The color difference between peri-implant mucosa and natural gingiva was visually evaluated by clinicians and rated as "clinically visible" or "clinically invisible" from speaking distance. The dimensions of peri-implant mucosa and gingiva at the mid-buccal aspect were evaluated by using cone-beam CT. Spearman analysis was performed to detect correlations between different variables. Two-sided t-test, ANOVA, Mann-Whitney, and Kruskal-Wallis tests were applied to detect differences between the groups. RESULTS: The spectrophotometrically assessed color difference ΔE between peri-implant mucosa and natural gingiva amounted to 7.0 ± 3.9. The peri-implant mucosa presented a significant dark, greenish and bluish discoloration in comparison with gingiva at control teeth. Clinical investigation revealed that in 60% of sites the color difference between peri-implant mucosa and natural gingiva was clinically visible from speaking distance. The threshold value ΔE for the extraoral clinical distinction of mucosal color differences measured 7.5. When comparing the groups with visible and invisible color differences with respect to the three color components, a significant difference was found only for chroma along yellow-blue axis. In the group with visible color difference, mucosa presented a bluish discoloration. Correlation analysis indicated that with an increase in mucosal thickness, a trend for smaller ΔE was found. CONCLUSION: The spectrophotometrically assessed color of the peri-implant mucosa revealed more dark, green and blue components compared to the natural gingiva. At 60% of the implants, peri-implant mucosal discoloration was visible from speaking distance. The sites with visible and those with invisible mucosal discolorations differed significantly only regarding the chroma along yellow-blue axis.

Guided bone regeneration and abutment connection augment the buccal soft tissue contour: 3-year results of a prospective comparative clinical study.

AIM: To test whether implant placement with simultaneous guided bone regeneration (GBR) differs from implant placement without GBR regarding the change in marginal mucosal contour. MATERIALS AND METHODS: In 28 patients, single implants were placed >4 months after tooth extraction. Eighteen implants were completely surrounded by native bone, and no bone augmentation was performed. At 10 implant sites, bone defects and thin bone plates were grafted with deproteinized bovine-derived bone mineral and covered with collagen membrane. Impressions were taken prior to implant placement (baseline), at 3 months before abutment connection, at 6 months immediately after crown insertion, at 1 year, and at 3 years. Models were optically scanned and 3D images were superimposed for the evaluation of mucosal contour changes at the mid-buccal aspect. The nonparametric Mann-Whitney U-test was applied to detect differences. RESULTS: From baseline to 6 months, horizontal contour change at the level 1 and 2 mm apical to the mucosal margin measured 0.65 ± 0.74 mm and 0.55 ± 0.56 mm at sites without GBR, and 1.92 ± 0.87 mm and 1.76 ± 0.70 mm at sites with GBR (P < 0.05). In the period from baseline to 1 year, the corresponding values amounted to 0.81 ± 0.67 mm and 0.60 ± 0.55 mm in the group without GBR, and to 1.81 ± 0.86 mm and 1.37 ± 0.62 mm in the group with GBR (P < 0.05). From baseline to 6 months, mucosal margin moved 0.16 ± 0.49 mm in the coronal direction in the group without GBR and 0.82 ± 0.65 mm in the group with GBR (P < 0.05). In the period from baseline to 1 year, vertical change of mucosal margin amounted to 0.64 ± 0.54 mm in the group without GBR and to 1.17 ± 0.53 mm in the GBR group (P < 0.05). From 1 to 3 years, the mucosal contours remained stable. CONCLUSIONS: Implant placement with simultaneous GBR resulted in more gain of buccal soft tissue contour in comparison with implant placement without GBR. Abutment connection increased the contour of the marginal mucosa at the augmented and the nonaugmented sites. GBR procedure contributed more to the contour gain than did the abutment connection. The augmented and the nonaugmented ridges exhibited stable peri-implant mucosal contour over a 3-year period.