A randomized clinical trial of phycogenic materials for sinus grafting with hydroxyapatite versus biphasic calcium phosphate: 2 years clinical outcomes.

OBJECTIVES: To assess in a prospective randomized trial two phycogenic bone substitutes-biphasic calcium phosphate (BCP) versus almost pure hydroxyapatite (HA)-for their volume stability and clinical implications after sinus floor elevation (SFE). MATERIALS AND METHODS: Twenty patients requiring lateral-window SFE 6 months prior to implant surgery were randomized to a BCP or HA group. As primary outcome, the grafts were analyzed for volume stability, using four cone-beam computed tomography scans obtained immediately/6/12/24 months after SFE. Secondary outcomes were implant survivval, success, periotest values, oral-health-related quality of life (OHIP-G14), and pain (VAS). RESULTS: Kolmogorov-Smirnov goodness-of-fit test revealed normal distribution of samples (p = .200). At 6/12/24 months, the augmented volumes decreased to 96/92/90% (HA) or 99/96/96% (BCP). Volume changes were significantly a factor of time (p < .001; generalized linear model with repeated measures) and reached significantly lower values in HA group (p = .018). Significant intergroup difference in volume losses was notable at 24 months (p = .021; t-test for independent samples). Periotest values decreased from -3/-4.1 (HA/BCP) after implant placement to -6.3/-4.5 (HA/BCP) after 6 months. OHIP scores diverged at 2 months (HA: 9.5; BCP: 5.2) and largely resolved by 24 months (HA: 1.3; BCP: 1.9). VAS scores were comparable, 2.2 at 1 week after SFE being their highest mean level. CONCLUSIONS: After 2 years, both groups experienced no biological or technical complications, demonstrating a consistent healing trajectory without notable symptoms. Although no significant differences were observed in implant stability and survival, BCP demonstrated higher volume stability than HA.

Influence of buccal bone wall thickness on the peri-implant hard and soft tissue dimensional changes: A systematic review

BACKGROUND: The significance on the association between the peri-implant bucco-lingual dimension (BLD) at the stage of implant placement and the occurrence of biological and esthetic complications is yet unknown. MATERIAL AND METHODSS: Systematic screening of electronic sources was carried out to identify clinical and preclinical studies reporting on the baseline BLD and/or buccal bone thickness (BBT) values. A secondary objective was to assess the effect of simultaneous grafting at sites with deficient or no buccal bone wall (BBW) at baseline. The primary outcome variables were BBT, BLD, and buccal vertical bone loss (VBL) at re-evaluation. Moreover, radiographic, clinical, and patient-reported outcome measures (PROMs) were evaluated. RESULTS: Overall, 12 clinical and four preclinical studies met the inclusion criteria. Inconsistencies were found in defining the critical BBT across the clinical and preclinical data evaluated. The clinical evidence demonstrated that during healing, dimensional changes occur in the alveolar bone and in the BBW that may compromise the integrity of the peri-implant bone, leading to VBL and mucosal recession (MR), particularly in scenarios exhibiting a thin BBW. The preclinical evidence validated the fact that implants placed in the presence of a thin BBW, are more prone to exhibit major dimensional changes and VBL. Moreover, the clinical data supported that, in scenarios where dehiscence-type defects occur and are left for spontaneous healing, greater VBL and MR together with the occurrence of biologic complications are expected. Furthermore, the augmentation of dehiscence-type defects is associated with hard and soft tissue stability. PROMs were not reported. CONCLUSIONS: Dimensional changes occur as result of implant placement in healed ridges that may lead to instability of the peri-implant hard and soft tissues. Sites presenting a thin BBW are more prone to exhibit major changes that may compromise the integrity of the buccal bone and may lead to biologic and esthetic complications.

Group 5 ITI Consensus Report: Implant placement and loading protocols.

OBJECTIVES: Working Group 5 was convened to discuss and find consensus on the topics of implant placement and loading protocols associated with single missing teeth in the anterior maxilla (aesthetic zone). Consensus statements, clinical recommendations, patient perspectives and future research suggestions were developed and presented to the plenary for discussion and approval. MATERIALS AND METHODS: Two systematic reviews were developed and submitted prior to the conference. The group considered in detail the systematic reviews and developed statements, clinical recommendations, patient perspectives and future research suggestions based on the findings of the reviews and experience of group members. Definitive versions were developed after presentation to and discussion by the plenary. RESULTS: Five consensus statements were developed and approved from each systematic review. Twelve clinical recommendations were developed by the group based on both reviews and experience. Three patient perspectives were developed, and five suggestions made for future research. CONCLUSIONS: Based on the findings of the systematic reviews and experience of group members, the Type 1A protocol (immediate placement and immediate loading), when utilized in the anterior maxilla under favorable conditions, is considered predictable and is associated with high survival rates. The procedure is considered clinically viable and is associated with aesthetic outcomes, although surgical, technical, and biological complications can occur.

Effect of laser-assisted reconstructive surgical therapy of peri-implantitis on protein biomarkers and bacterial load.

OBJECTIVES: This randomized clinical trial assessed changes in protein biomarker levels and bacterial profiles after surgical reconstructive therapy of peri-implantitis and investigated whether the adjunctive use of Er:YAG laser impacts protein biomarker and microbial outcomes. MATERIALS AND METHODS: Twenty-four patients received surgical reconstructive therapy for peri-implantitis with guided bone regeneration following mechanical debridement with (test) or without (control) the adjunctive irradiation of Er:YAG laser. Bacterial and peri-implant crevicular fluid (PICF) samples were collected over 6 months and analyzed with bacterial qPCR and luminex multiplex assays. RESULTS: Surgical reconstructive treatment significantly affected the concentration of PICF protein biomarkers, including a 50% reduction in IL-1ß between 2 and 4 weeks (p < .0001). Both MMP-9 (p < .001) and VEGF (p < .05) levels steadily decreased after treatment. In the laser group, the peak increase in IL-1ß was attenuated at 2 weeks, followed by significant reduction in MMP-9 (p < .01) and VEGF (p < .05) across all follow-up appointments compared with the control nonlaser group. The total bacterial load was reduced 2 weeks after treatment, especially in the laser group, but recolonized to presurgical levels after 4 weeks in both groups (p < .01). The composition of selective pathogens varied significantly over the follow-up, but recolonization patterns did not differ between groups. CONCLUSIONS: Reconstructive therapy of peri-implantitis significantly altered PICF protein biomarker and microbial levels during the healing process. The adjunctive use of Er:YAG laser significantly modulated the inflammatory response through reduced levels of MMP-9 and VEGF during the postsurgical period. The bacterial load was reduced immediately after therapy, but recolonization was observed by 4 weeks in both groups.

Influence of buccal bone wall thickness on the peri-implant hard and soft tissue dimensional changes: A systematic review.

BACKGROUND: The significance on the association between the peri-implant bucco-lingual dimension (BLD) at the stage of implant placement and the occurrence of biological and esthetic complications is yet unknown. MATERIAL AND METHODS: Systematic screening of electronic sources was carried out to identify clinical and preclinical studies reporting on the baseline BLD and/or buccal bone thickness (BBT) values. A secondary objective was to assess the effect of simultaneous grafting at sites with deficient or no buccal bone wall (BBW) at baseline. The primary outcome variables were BBT, BLD, and buccal vertical bone loss (VBL) at re-evaluation. Moreover, radiographic, clinical, and patient-reported outcome measures (PROMs) were evaluated. RESULTS: Overall, 12 clinical and four preclinical studies met the inclusion criteria. Inconsistencies were found in defining the critical BBT across the clinical and preclinical data evaluated. The clinical evidence demonstrated that during healing, dimensional changes occur in the alveolar bone and in the BBW that may compromise the integrity of the peri-implant bone, leading to VBL and mucosal recession (MR), particularly in scenarios exhibiting a thin BBW. The preclinical evidence validated the fact that implants placed in the presence of a thin BBW, are more prone to exhibit major dimensional changes and VBL. Moreover, the clinical data supported that, in scenarios where dehiscence-type defects occur and are left for spontaneous healing, greater VBL and MR together with the occurrence of biologic complications are expected. Furthermore, the augmentation of dehiscence-type defects is associated with hard and soft tissue stability. PROMs were not reported. CONCLUSIONS: Dimensional changes occur as result of implant placement in healed ridges that may lead to instability of the peri-implant hard and soft tissues. Sites presenting a thin BBW are more prone to exhibit major changes that may compromise the integrity of the buccal bone and may lead to biologic and esthetic complications.

Systematic review on the association between genetic polymorphisms and dental implant-related biological complications.

OBJECTIVES: The aim of this systematic review was to evaluate the association between specific genetic polymorphisms and dental implant-related biological complications in patients having a follow-up period of at least 12-months post-loading. MATERIAL AND METHODS: A sensitive search strategy was developed to identify implant-related genetic-association studies. This was performed by searching five databases. A three-stage screening (titles, abstract, full text) was carried out in duplicate and independently by two reviewers. Assessment was carried out according to the suggested scale for quality assessment of periodontal genetic-association studies and adapted to genetic analyses of implant-related studies leading to an overall final score 0-20 based on the summation of positive answers. RESULTS: The initial search resulted in 1838 articles. Sixty-seven full-text articles were assessed for eligibility and four studies met the defined inclusion criteria. IL-6 G174C, TNF-α -308, IL-1A-889 and IL-1B+3954 and CD14-159 C/T polymorphisms were evaluated. The quality assessment scores ranged from 6 to 11 positive answers from out of a maximum score of 20. The great heterogeneity among the studies did not allow a meta-analysis. CONCLUSIONS: The published evidence on genetic predisposition and implant biologic complications is limited. The small number of identified studies evaluating the association between genetic polymorphisms and peri-implant disease presented methodological and reporting inadequacies. Thus, the potential link between genetic polymorphisms and biological complications should be further investigated and clarified through well-designed clinical studies on adequately powered and appropriately included study populations.

Effects of masticatory loading on bone remodeling around teeth versus implants: Insights from a preclinical model.

OBJECTIVES: Teeth connect to bone via a periodontal ligament, whereas implants connect to bone directly. Consequently, masticatory loads are distributed differently to periodontal versus peri-implant bone. Our objective was to determine how masticatory loading of an implant versus a tooth affected peri-implant versus periodontal bone remodeling. Our hypothesis was that strains produced by functional loading of an implant would be elevated compared with the strains around teeth, and that this would stimulate a greater degree of bone turnover around implants versus in periodontal bone. MATERIALS AND METHODS: Sixty skeletally mature mice were divided into two groups. In the implant group, maxillary first molars (mxM1) were extracted, and after socket healing, titanium alloy implants were positioned subocclusally. After osseointegration, implants were exposed, resin crowns were placed, and masticatory loading was initiated. In the control group, the dentition was left intact. Responses of peri-implant and periodontal bone were measured using micro-CT, histology, bone remodeling assays, and quantitative histomorphometry while bone strains were estimated using finite element (FE) analyses. CONCLUSIONS: When a submerged osseointegrated implant is exposed to masticatory forces, peri-implant strains are elevated, and peri-implant bone undergoes significant remodeling that culminates in new bone accrual. The accumulation of new bone functions to reduce both peri-implant strains and bone remodeling activities, equivalent to those observed around the intact dentition.

Clinical performance of narrow-diameter implants with hydrophobic and hydrophilic surfaces with mandibular implant overdentures: 1-year results of a randomized clinical trial.

OBJECTIVE: To compare peri-implant clinical and radiographic parameters between hydrophilic and hydrophobic narrow dental implants in patients with mandibular implant overdentures for 1 year. MATERIALS AND METHODS: In a randomized, double-blind, split-mouth study with a 1-year follow-up, sixteen edentulous participants received two narrow-diameter implants in the anterior mandibular region with 2 types of surfaces: hydrophobic (Neoporos surface, NS) and hydrophilic (Acqua surface, AS). During the osseointegration period and after loading with mandibular implant overdentures, the outcomes monitored were (i) peri-implant health: early healing index (EHI), visible plaque index (VPI), calculus presence (CP), peri-implant inflammation (PI), probing depth (PD), and bleeding on probing (BOP); (ii) implant stability quotient (ISQ), (iii) crestal bone loss (CBL) and bone level change (BLC); and (iv) implant success and survival rates. RESULTS: The PD in NS implants decreased by 31.78% between 15 and 30 days, while a similar reduction (-31.28%) occurred in the 3rd month in the AS group. The ISQ also decreased significantly during the 1st month in both groups: -10.95% after 7 days in the NS group and -7.46% after 15 days in the AS group. At 12 months, statistically significant differences were not observed; however, the AS surface presented 50.6% smaller CBL and 41.3% smaller BLC values. The success and survival rates were 62.5% for AS implants and 87.5% for NS implants. CONCLUSION: Narrow-diameter implants with hydrophilic and hydrophobic surfaces loaded with mandibular implant overdentures showed no differences in peri-implant healing, stability, and peri-implant bone remodeling in the 1st year of follow-up.

Bone heating and implant removal using a high-frequency electrosurgical device: An in vivo experimental study.

OBJECTIVES: Failed implant removal using a high-frequency electrosurgical device (HFED) has been reported to be less invasive than other surgical techniques. We sought to clarify the mechanism of removal torque reduction in an implant by heating with HFED. MATERIALS AND METHODS: Sixty-eight Wistar rats received titanium implants on the maxillary bone 4 weeks after extraction of the first and second molars. The control group was sacrificed 6 weeks after implant installation. In the experimental group, the implant was heated by HFED for 10 s using three different power outputs, and samples were collected at 3, 7, and 14 days after heating. Removal torque measurement and histological analysis were performed in the control and experimental groups. Implant surfaces were observed using an electron-probe microanalyzer (EPMA). Data were analyzed using Mann-Whitney U test at a significance level of 5%. RESULTS: The removal torque could not be measured in the control group due to fracture of the implant. After heating, the removal torque was measurable without fracture and decreased significantly at 14 days as compared with that at 3 days (p < .05). Heating with "min" power output resulted in a significantly smaller blank lacunae area and fewer osteoclasts at 14 days after heating (p < .05). EPMA revealed bone matrix adherence to outer surface of heated implant. CONCLUSIONS: After heating, an enlarged area of blank lacunae around the implant and an increased number of osteoclasts into the bone marrow cavity were observed, which may have contributed to the reduction in removal torque.

The comparative evaluation of transcrestal and lateral sinus floor elevation in sites with residual bone height ≤6 mm: A two-year prospective randomized study.

OBJECTIVES: To compare clinical and radiographic outcomes between transcrestal sinus floor elevation (TSFE) and lateral sinus floor elevation (LSFE) approaches of simultaneous implant placement in atrophic maxilla. MATERIALS AND METHODS: Patients with a residual bone height (RBH) ≤6 mm were enrolled and randomly assigned to TSFE and LSFE groups. Patients in both groups simultaneously underwent sinus floor elevation with bovine-derived xenograft and implant placement. Clinical and radiographic results were evaluated immediately after surgery and after 6, 12, 18, and 24 months. The endo-sinus bone gain (ESBG), apical implant bone height (ABH), endo-sinus bone-implant contact rate (EBICR), and crestal bone level (CBL) were assessed using panoramic radiographs. RESULTS: Forty-one implants (TSFE: 21, LSFE: 20) were placed in cases with a mean RBH of 3.77 ± 1.16 mm. All implants obtained clinical success and satisfactory ESBG at 24 months. No significant differences were found in ESBG and ABH between two groups immediately after surgery, but LSFE group showed significantly higher values than TSFE group thereafter. Grafts in TSFE group reached stability 6 months earlier than that in LSFE group. In both groups, EBICR was almost 100%, and CBL showed no detectable changes. CONCLUSIONS: LSFE can achieve higher ESBG 2 years after surgery. Otherwise, TSFE could be an alternative to LSFE, when the access for lateral window preparation is limited. Both approaches were highly predictable for RBH ≤6 mm during 24-month observation period for the implants placed simultaneously.

Prospective randomized clinical trial evaluating the effects of two different implant collar designs on peri-implant healing and functional osseointegration after 25 years.

OBJECTIVES: Evaluate the effects of two different machined-collar lengths and designs on peri-implant healing. MATERIAL AND METHODS: An implant with a microtextured surface and 3.6mm-long internal-connection machined collar was compared to two implants that had an identical 1.2mm-long external-connection machined collar, but one had the microtextured surface while the other's was machined. Participants received the three implants, with microgap at the crest, alternately at five sites between mental foramen, and a full-arch prosthesis. Peri-implant bone levels were measured after 23 to 26 years of function. Keratinized tissue height, plaque, probing depth, bleeding, and purulence were also evaluated. Descriptive and mixed models for repeated\measures analyses were used, with Bonferroni correction for pairwise comparisons. RESULTS: Twenty-two participants (110 implants) were evaluated at the 25-year examination. Microtextured implants with the longer machined collar had significantly greater mean marginal bone loss (-1.77mm ± 0.18, mean ± SE) than machined (-0.85mm ± 0.18, p < .001) and microtextured (-1.00 ± 0.18mm, p < .001) implants with the shorter machined collar. Keratinized tissue height was greater for internal-connection (0.74mm ± 0.10) versus external-connection (0.51 ± 0.08, p =  0.01) microtextured implants. No differences were observed for plaque (p = 0.78), probing depth (p = 0.42), bleeding (p  = 0.07), and purulence (p = 1.00). Implant survival rate was 99%. CONCLUSIONS: Implants with the 1.2mm machined collar limited bone loss to 1mm, while those with the longer machined collar showed > 1.5mm loss after 25 years of function with microgap at the crest. Internal-connection design and fixture surface microtexturing did not result in greater bone preservation. ClinicalTrials.gov Identifier: NCT03862482.

Implantoplasty: Carbide burs vs diamond sonic tips. An in vitro study.

OBJECTIVES: Implantoplasty (IP) is a treatment option for peri-implantitis. Mechanical concerns were raised on fracture resistance of implants subjected to this procedure. This study aimed to compare two methods of IP in terms of implant wear and fracture resistance, and of surface topography. MATERIAL AND METHODS: Eighteen cylindrical screw-shaped dental implants (4 mm diameter, 13 mm length) with an external hexagonal connection were used. IP was performed on the first 6-mm implant surface with a sequence of burs or diamond sonic tips, both followed by an Arkansas finishing. IP duration and implant weight variation were recorded. Micro-computed tomography (micro-CT) was used to evaluate material loss. Implant fracture resistance was assessed by static compression test. Surface topography analysis was performed with a stylus profilometer. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) was applied for implant surface morphology and elemental characterization. RESULTS: Micro-CT showed less material loss in sonic compared to burs. No statistically significant difference was found between the mean fracture resistance values reached in bur and sonic, both followed by Arkansas, and with respect to control. IP performed with burs led to a smoother surface compared to sonic. Equivalent final surface roughness was found after Arkansas in both IP procedures. SEM-EDS showed a deburring effect associated to sonic and revealed carbon and aluminum peaks attributable to contamination with sonic diamond tips and Arkansas bur, respectively. CONCLUSIONS: IP with sonic diamond tips was found to be more conservative in terms of structure loss. This could have a clinical relevance in case of narrow-diameter implants.

Xerostomia aggravates ligation-induced peri-implantitis: A preclinical in vivo study.

OBJECTIVES: Previous studies have indicated that xerostomia is a critical factor affecting periodontitis; nonetheless, it is controversial whether xerostomia impairs peri-implant tissue. The objective of this experimental study was to evaluate the effect of xerostomia on the peri-implant hard and soft tissues in the rat model. MATERIALS AND METHODS: Implants were placed in bilateral maxillae of male Wistar rats. The animals underwent submandibular and sublingual gland resection on both sides (DRY group) or sham operation (CTR group). Silk ligatures were placed around one side of abutments, which were randomly selected in each animal. The effects of xerostomia were assessed using micro-CT, histological analysis, real-time PCR, and 16S rRNA-based metagenomic analysis. RESULTS: Ligation with silk thread caused bone resorption around implants. Although xerostomia itself did not induce bone resorption, it significantly enhanced silk ligature-mediated bone resorption around implants. Histological analysis and real-time PCR indicated that xerostomia induced inflammation and osteoclastogenesis around implants with silk ligatures. Furthermore, it altered the microbiota of the plaque on the silk thread around implants. CONCLUSION: Xerostomia accelerates mucosal inflammation and osteoclastogenesis, which aggravates bone resorption around implants.

Marginal bone loss and the risk indicators of fixed screw-retained implant-supported prostheses and fixed telescopic-retained implant-supported prostheses in full arch: A retrospective case-control study.

OBJECTIVES: This study compared full-arch screw-retained implant-supported fixed dental prostheses (FSI-FDPs) and full-arch telescopic-retained implant-supported fixed dental prostheses with a professional retrieval system (FTI-FDPs) on marginal bone loss (MBL), the risk indicators and peri-implantitis rate after 7-13 years. MATERIAL AND METHODS: Sixty five edentulous patients were treated with 86 prostheses and 592 implants. The FSI-FDP group comprised 26 patients (32 prostheses, 202 implants), and the FTI-FDP group comprised 39 patients (54 prostheses, 390 implants). MBL and the risk indicators of MBL ≥1 mm were assessed. Peri-implantitis rates at 13 years were also calculated. RESULTS: Full-arch screw-retained implant-supported fixed dental prostheses and FTI-FDP implants exhibited comparable mean MBLs of 0.60 ± 0.51 and 0.41 ± 1.03 mm, respectively. MBL ≥1 mm was noted for 25% of FSI-FDP implants and 6.9% of FTI-FDP implants. Superstructure-abutment connection (screw retention:FSI-FDPs >telescopic retention:FTI-FDPs) and implant-abutment connection (External butt joint, Internal butt joint >Morse taper joint) were associated with MBL ≥1 mm. Peri-implantitis rates at the implant level were 3.99% (95%CI = 3.93-20.5) in FSI-FDP group and 3.85% (95%CI = 3.85-34.3) in FTI-FDP group with no significance. CONCLUSIONS: It was concluded that FSI-FDP and FTI-FDP implants exhibited comparable MBL; however, the risk of MBL ≥1 mm in FTI-FDPs was lower than in FSI-FDPs. Besides, implant-abutment connection was the risk indicator of MBL ≥1 mm. In peri-implantitis rate, FSI-FDPs and FTI-FDPs behave similarly.

The biomechanical profile of an osseo-integrated rectangular block implant: A pilot in vivo experimental study.

OBJECTIVE: A novel implant design, the rectangular block implant (RBI), was investigated as a possible solution to the restoration of the posterior resorbed ridge. AIM: To maximally load test the osseo-integrated RBI in shear and tensile loads and relate these findings to known human masticatory loads as biomechanical proof of the study concept. MATERIALS AND METHODS: Twelve RBIs were design-manufactured and placed into posterior mandibular saddles in 3 mature greyhound dogs.-2 per left and right. After 12 weeks of healing, osseo-integration was confirmed using resonance frequency analysis (RFA) and wrench torque tests. Three bone blocks each with two RBIs were dissected and mounted in acrylic. Micro-computerized tomography (µ-CT) was performed to assess bone to implant contact (BIC), and load analysis was performed using a Universal Test System. Three force applications were conducted until failure: pull-out (tensile), buccal push from the lingual (shear) and distal push from the mesial (shear). The osteotomy sites were examined using light magnification and scanning electron microscopy (SEM). RESULTS: Pull-out, buccal and distal force failures occurred at differing levels. Post-detachment sites showed complex patterns of bone failure, including trabecular and cortical fracture, as well as shearing at varying distances from the BIC. Interfacial shear strength was calculated at 14.4 MPa. CONCLUSION: The osseo-integrated RBIs were able to withstand simulations of the demanding axially, bucco-lingually and mesio-distally oriented biomechanical challenges of the posterior saddle, under conditions of reduced bone volume. These values exceeded equivalent force components of maximal masticatory loads in humans.

Hard and soft tissue healing around implants with a modified implant neck configuration: An experimental in vivo preclinical investigation.

OBJECTIVES: Evaluate the dimensions and morphology of peri-implant tissues around a modified dental implant designed with tissue level connection and a convergent transmucosal neck, when compared with a conventional bone level implant connected to a cylindrical machined titanium abutment. MATERIAL AND METHODS: Eight experimental animals were used for this in vivo investigation, in whom 16 test and 16 control implants were placed following a random allocation sequence. The following histological outcomes at 4 and 12 weeks were evaluated: morphology of peri-implant tissues, the soft tissue height and thickness, the horizontal and vertical bone remodeling, and the bone to implant contact (BIC). RESULTS: In both early (4 weeks) and late (12 weeks) healing times, there were no statistically significant differences between test and control implants, with respect to the overall height and thickness of the peri-implant hard and soft tissues. There was a tendency toward a more coronal free gingival margin (I-FGM) at the buccal aspect of test when compared to control implants (at 4 weeks, difference of 0.97 mm (p = .572) and 0.30 mm (p = 1.000) at 12 weeks). Similarly, there was a tendency toward a more coronal position of the first bone to implant contact (I-B) at the buccal aspect of test as compared to control implants (1.08 mm (p = 0.174) at 4 weeks and 0.83 mm (p = 0.724) at 12 weeks). CONCLUSIONS: Hard and soft tissue healing occurred at both implant types with no statistically significant differences. Test implants tended to present a more coronal gingival margin (FGM) and first bone to implant contact (B).

Influence of implant geometry and osteotomy design on early bone healing: A pre-clinical in vivo study.

OBJECTIVES: To analyze the early stages of osseointegration around implants with different geometry following installation in sites using different osteotomy protocols. MATERIALS AND METHODS: Two types of implants were installed using regular or modified (reduced diameter) osteotomy protocols in mandibular premolar/molar regions following tooth extraction in six dogs. Three implant site categories were created: Reference (A implant and regular osteotomy), Test-1 (B implant and regular osteotomy), and Test-2 (B implant and modified osteotomy). Implant installation procedures were repeated after 4 and 6 weeks. The insertion torque (ITQ) was measured during implant installation and resonance frequency analysis providing implant stability quotient (ISQ) values was performed following implant installation and once every week during the course of the study. Biopsies were obtained immediately after the 3rd installation procedure and prepared for histological analysis. RESULTS: The modified osteotomy protocol created a higher insertion torque (ITQ). The analysis also revealed a correlation between insertion torque at implant installation and radiographic bone loss after 6 weeks of healing. The decline in ISQ values during healing was more pronounced at Test-2 than other sites. While the degree of bone-to-implant contact (BIC%) in the marginal area was similar in test and reference sites at 6 weeks of healing, Test-2 implants presented with a significantly higher BIC% in the mid and apical areas than Test-1 implants. CONCLUSIONS: It is suggested that placement of implants in undersized osteotomy sites will result in an increased remodeling of the cortical bone during the early healing process.

Cemented versus screw-retained posterior implant-supported single crowns: A 24-month randomized controlled clinical trial.

OBJECTIVES: To compare the incidence of biological and technical complications of cemented and screw-retained monolithic lithium-disilicate implant-supported posterior single crowns. MATERIAL AND METHODS: Forty-one subjects with a total of 56 implants received randomly allocated 28 cemented and 28 screw-retained crowns. In the screw-retained group, monolithic lithium-disilicate restorations were luted to titanium bases extraorally. In the cemented group, monolithic lithium-disilicate crowns were cemented on individualized titanium abutments intraorally. All restorations were examined according to modified FDI criteria within 2 weeks of inserting the crowns (baseline) and after 12 (n = 46) and 24 (n = 43) months. Bone loss was evaluated by standardized radiographs at baseline and 12 months. RESULTS: After 12 months, the incidence of mucositis (positive bleeding on probing) was 14.2% (screw-retained) and 17.9% (cement-retained). The gingival and plaque index and a mean marginal bone loss between 0.03-0.15 mm showed no significant difference between the groups. In the cemented group, cement residues were detected at baseline at two restorations (6.9%) by radiographic examination. A complete digital workflow was realized in most cases (85.7%). At 24 months, no restoration had failed, and no chipping of the ceramic had occurred. In the screw-retained group, screw loosening occurred in one implant. In both groups, there was obvious deterioration in the quality of 32% of the occlusal and of 18% of the proximal contact points. CONCLUSIONS: The type of retention mode of monolithic implant-retained lithium-disilicate posterior crowns had no influence on the biological and technical complication rate.

Periimplant bone changes in different abutment heights and insertion timing in posterior mandibular areas: Three-year results from a randomized prospective clinical trial.

AIM: To compare the influence of the abutment height and its insertion timing on the marginal bone change (MBC) variation of implants placed at posterior mandibular partial edentulous areas in a medium follow-up period. MATERIAL AND METHODS: This randomized clinical trial (RCT) comprised a sample of patients with posterior mandibular edentulous areas, treated with at least two implants and distributed into three groups: implants connected to a 2 mm height abutment during the surgical stage (Group A); implants connected to a 1 mm height abutment during the surgical stage (Group B); and implants connected to a 2 mm height abutment after 2 months (Group C). Clinical and radiographic measurements were performed during a 36-month period (T4). The MBC was set as the main variable in study. Statistical significance was set at 0.05. RESULTS: A total of 29 subjects and 59 implants were enrolled in this study. A mean MBC of 0.35 ± 0.46 mm, 0.60 ± 0.81 mm, and 0.71 ± 0.90 mm was computed for groups A, B and C, respectively, at T4. Significant differences were found between groups A and C in terms of MBC variation after 3 years of treatment (p = .048). Multiple linear regression analysis showed a significant influence of the first-year MBC and the abutment insertion timing has independent predictor variables for the MBC assessed at T4. CONCLUSION: The installation of 2-mm prosthetic abutments, at the time of implant placement, in areas with limited keratinized mucosa presents as a favorable treatment option in terms of periimplant marginal bone maintenance.

Mechano-adaptive Responses of Alveolar Bone to Implant Hyper-loading in a pre-clinical in vivo model.

OBJECTIVES: Oral implants transmit biting forces to peri-implant bone. In turn, those forces subject peri-implant bone to mechanical stresses and strains. Here, our objective was to understand how peri-implant bone responded to conditions of normal versus hyper-loading in a mouse model. MATERIAL AND METHODS: Sixty-six mice were randomly assigned to 2 groups; both groups underwent bilateral maxillary first molar extraction followed by complete healing. Titanium alloy implants were placed in healed sites and positioned below the occlusal plane. After osseointegration, a composite crown was affixed to the implant so masticatory loading would ensue. In controls, the remaining dentition was left intact but in the hyper-loaded (test) group, the remaining molars were extracted. 3D finite element analysis (FEA) calculated peri-implant strains resulting from normal and hyper-loading. Peri-implant tissues were analyzed at multiple time points using micro-computed tomography (µCT) imaging, histology, enzymatic assays of bone remodeling, and vital dye labeling to evaluate bone accrual. RESULTS: Compared to controls, hyper-loaded implants experienced a 3.6-fold increase in occlusal force, producing higher peri-implant strains. Bone formation and resorption were both significantly elevated around hyper-loaded implants, eventually culminating in a significant increase in peri-implant bone volume/total volume (BV/TV). In our mouse model, masticatory hyper-loading of an osseointegrated implant was associated with increased peri-implant strain, increased peri-implant bone remodeling, and a net gain in bone deposition. CONCLUSION: Hyper-loading results in bone strain with catabolic and anabolic bone responses, leading to a net gain in bone deposition.