The International Journal of Oral & Maxillofacial Implants, 05/2017

Purpose: Achievement of high insertion torque values indicating good primary stability is a goal during dental implant placement. The objective of this study was to evaluate whether or not two-piece implants made from zirconia ceramic may be damaged as a result of torque application. Materials and Methods: A total of 10 two-piece zirconia implants were repeatedly inserted into polyurethane foam material with increasing density and decreasing osteotomy size. The insertion torque applied was measured, and implants were checked for fractures by applying the fluorescent penetrant method. Weibull probability of failure was calculated based on the recorded insertion torque values. Results: Catastrophic failures could be seen in five of the implants from two different batches at insertion torques ranging from 46.0 to 70.5 Ncm, while the remaining implants (all belonging to one batch) survived. Weibull probability of failure seems to be low at the manufacturerrecommended maximum insertion torque of 35 Ncm. Chipping fractures at the thread tips as well as tool marks were the only otherwise observed irregularities. Conclusion: While high insertion torques may be desirable for immediate loading protocols, zirconia implants may fracture when manufacturer-recommended insertion torques are exceeded. Evaluating bone quality prior to implant insertion may be useful. Keywords: dental implant, fluorescence penetrant method, fracture torque, zirconia

Purpose: To test the adhesion properties of live gingival fibroblasts to three different implant abutment materials after five different cleaning procedures. Materials and Methods: Highly polished discs of lithium disilicate (LS), zirconium dioxide (Zr), and titanium alloy (Ti) were fabricated. The specimens were cleaned by one of five different methods: steam (S), argon plasma (AP), ultrasound and disinfection (UD), ultrasound and sterilization in an autoclave (UA), or photofunctionalization with high-intensity ultraviolet light (PF). Cell detachment force (adhesion) was measured by single-cell force spectroscopy, which is a method to quantify cell adhesion at the single cell level. Data were statistically analyzed using parametric tests (analysis of variance [ANOVA], t tests). Results: Cell detachment forces in the low nN regime were recorded in all experiments. Significant differences in cell adhesion on the different materials were found as a function of the cleaning method (P ≤ .0001). For LS abutments, no significant differences between the cleaning methods could be found (P > .05). For Zr specimens, the AP method showed the highest cell detachment forces, followed by UD, PF, S, and UA (S/UD, S/UA, S/PF, AP/UD, and UD/PF were not significantly different from each other). For Ti abutments, UD showed the highest cell detachment forces, followed by S, AP, and UA/PF (S/UD, S/UA, S/PF, AP/U, and UA/PF were not significantly different from each other). Conclusion: All cleaning methods provided comparable cell detachment forces for LS abutments. AP/PF or ultrasonic cleaning were the most suitable methods for strong cell adhesion on Zr. UD provided the best cell adhesion for Ti. Keywords: cell adhesion, ceramic, cleaning methods, dentin, lithium disilicate, physico-chemical properties, resin cement, single-cell force spectroscopy, surface treatment, titanium alloy, zirconium dioxide

Purpose: To identify whether reuse or replacement is better for managing loose screws. Materials and Methods: An electronic search was performed utilizing PubMed, and a further manual search of the reference lists of relevant reviews and articles was conducted. Selected inclusion and exclusion criteria were used to limit the search. Results: The electronic and manual search provided 243 titles and abstracts. Fulltext analysis was performed for 98 articles, resulting in a total of 15 articles that qualified for inclusion in this study. All the included articles reported that loose screws were reused and retightened or were replaced by new screws. The time of screw loosening ranged from 1 month to 3 years after delivery. Available details of numbers and frequency of screw loosening permitted only limited analysis from very few articles. A total of 44 loose screws reported in two articles did not loosen again after retightening once. Conclusion: From the very limited available literature, it appears that retightening an occlusal screw or abutment screw is an acceptable procedure, as the evidence shows that retightened screws seem to remain tight. Replacement of screws as a routine procedure cannot be recommended. Routine assessment of screw tightness is recommended to minimize additional and more severe complications. Keywords: dental implant, screw loosening, screw-retained, systematic review

Purpose: Aftermarket computer-aided design/computer-assisted manufacture (CAD/CAM) milled zirconia (Zr) abutments were recently introduced with minimal independent research regarding their fracture resistance. Thirdparty manufacturers often alter the original equipment manufacturers' (OEM) design with unknown effects on fracture resistance. These alterations include elimination of the titanium insert with subsequent introduction of Zr into the implant, changes to connection designs and shapes, and/or alterations to prosthetic screw design. This in vitro study compares the static load fracture resistance and mode of failure of alternatively engineered Zr abutments with those of prefabricated (OEM) Zr abutments with internal, external, and conical connections. Materials and Methods: Twenty Zr stock abutments (five per group) from OEMs were selected to demonstrate fracture resistance of external hex, internal connection, and conical connection implant designs (control groups). Atlantis abutments (Dentsply) (test group) were manufactured by means of CAD/CAM to match the OEM abutments (control groups). All samples had full-coverage all-ceramic crowns luted to the abutments. Static load fracture resistance was evaluated with an Instron test device. Modes of abutment failure were evaluated using both light and scanning electron microscopy. Results: A Welch two-sample t test evaluated the OEM control groups vs the Atlantis test groups. Static load to failure (N) for each representative control group vs test group revealed (1) conical design OEM (387 N) vs Atlantis (211 N) (P < .011), (2) external-hex OEM (408 N) vs Atlantis (218 N) (P < .035), (3) trilobe internal connection OEM (430 N) vs Atlantis (260 N) (P < .014), and (4) internal connection OEM (448 N) vs Atlantis (244 N) (P < .02). Conclusion: Atlantis CAD/CAM Zr abutments demonstrated static fracture loads lower than those of their OEM counterparts. Failure modes were Zr fractures in the conical and external hex groups. The internal connection groups demonstrated a mixed mode of failure, with screw head fracture 100% of the failures in the internal Zr connection group. The trilobe internal connection group exhibited screw-head fracture in two of five samples and Zr fracture in the remaining three samples. Clinicians should consider avoiding the alternatively engineered Atlantis Zr abutment for restoration of posterior single teeth in cases in which occlusal forces may exceed 350 to 400 N. Keywords: CAD/CAM abutment, implant-abutment fracture, zirconia abutment

Purpose: The aim of this systematic review was to investigate which material is the most effective bone substitute for alveolar bone healing by evaluating histomorphometric outcomes after healing of postextraction sockets in humans. Materials and Methods: A manual and electronic search (PubMed, EMBASE, Cochrane Library) was performed using a search string prepared ad hoc. Data were statistically analyzed by calculating weighted mean percentage of new bone formation (primary outcome) and weighted mean percentage of residual biomaterial, soft/connective tissue, and nonmineralized tissue (secondary outcomes) in the biopsies. A meta-analysis of the included randomized controlled trials (RCTs) was performed. Results: A total of 802 papers were screened. After application of the inclusion and exclusion criteria, a total of 40 articles were included in the quantitative synthesis while 11 were included in the meta-analysis of comparative studies. The evaluation of comparative studies with empty sites as control showed that bovine bone could lead to a lower proportion of new bone formation compared to sites left to heal spontaneously (P < .00001). Magnesium-enriched hydroxyapatite and porcine bone showed a significantly higher percentage of new bone compared to control sites (P < .00001). Grafting with an allograft did not lead to a higher percentage of new bone formation in comparison with control sites (P = .09). Conclusion: There was no evidence for the superiority of a given biomaterial over the others in terms of new bone formation. While calcium sulphate and beta-tricalcium phosphate resorbed faster than other biomaterials, xenografts showed a lower resorption rate than allografts. Comparative studies suggested that bovine bone was related to a lower proportion of new bone volume compared to sites left to heal spontaneously, while porcine bone and magnesium-enriched hydroxyapatite were related to higher new bone volume. Allograft was not related to higher new bone volume than sites healed without any biomaterial.

Purpose: Rotational errors of implants can occur during two stages: when connecting impression copings with implants, and when connecting impression copings with analogs. The aim of this study was to determine ways to minimize these rotational errors. Materials and Methods: Three types of implants were prepared: a tissue-level implant with an internal octagon 8-degree Morse taper connection, a bone-level implant with an internal hex 11-degree Morse taper connection, and a bone-level implant with an external hex connection. Each complex (n = 10 per group) was composed of an implant, an impression coping, and an analog. Implants were embedded in resin blocks and connected with corresponding impression copings. Analogs that reproduced the position of the implants were created by means of a custom-made transfer jig, and rotational errors were measured between implants and analogs. Impression copings and analogs were connected by means of four methods: The impression coping was connected to the implant in a clockwise (CW) or a counterclockwise (CCW) direction before tightening, and the analogs were then connected with impression copings and tightened using a hemostat (Hs) or by hand (Hd). Results: The CW-Hs and CCW-Hd groups exhibited low rotational error (mean ± standard deviation 0.11 ± 0.21 and 0.19 ± 0.34 degrees, respectively), whereas the CW-Hd and CCW-Hs groups exhibited high rotational error (−1.80 ± 0.67 and 2.07 ± 0.75, respectively) in different directions. A strong association was observed between the tightening method and rotational error, and a weak association was observed between the connection type and rotational error. Conclusion: The CW-Hs method was found to be the most suitable for minimizing rotational error between implants and analogs. Keywords: clockwise, counterclockwise, implant prosthesis, impression method, rotational error, rotational freedom

Objective: To test whether a Maryland bridge-type splint provides adequate stability for a custom root-shaped implant to osseointegrate in a manner substantially equivalent to that of a threaded implant. Methods: Six beagle dogs were subjected to intraoral impressions and cone beam scans that were used to fabricate custom root-shaped implants (RTIs) and crowns. Premolars in the mandible (P4) and in the maxilla (P3) were extracted, and 24 RTIs were immediately placed in extraction sockets. Splint extensions of the crowns were bonded to mesial and distal teeth. Twelve mandibular molars (M2) were extracted, and threaded implants (DXI), serving as controls, were placed immediately. Animals were placed on a soft diet after surgery. Weekly intraoral photographs and radiographs were taken, and animals were sacrificed at 4 months. Fluorescent labels were injected 35, 21, and 7 days before sacrifice. Clinical implant stability and vertical pullout forces were tested, and loss of vertical bone height was measured on radiographs. Histomorphometric measurements of percent bone-to-implant contact (BIC) and mineral apposition rates were made from undecalcified sections. Results: Three RTI splints broke or debonded, and the implants were removed. No loss of DXI implants was noted. All remaining implants were clinically stable. Mean pullout forces were 366.7 ± 182.8 N for RTI (no pullout data for the threaded DXI). Mean vertical bone loss was 0.4 ± 0.6 mm mesially and 0.2 ± 0.7 mm distally for RTI and 0.8 ± 1.1 mm mesially and 0.8 ± 1.0 mm distally for DXI, with no significant differences between groups. BIC values were 70.8% ± 12.7% for mandibular RTI, 68.3% ± 11.6% for maxillary RTI, and 78.8% ± 5.5% for DXI. Mineral apposition rates within local osteons were 1.9 ± 0.5 μm for RTI and 1.7 ± 0.3 μm for DXI; at the implant surface, they were 2.5 ± 1.2 μm for RTI and 3.3 ± 1.8 μm for DXI, with no significant differences between groups. Conclusion: All RTIs with intact splints exhibited clinically successful integration, similar to that of control threaded implants. The RTI may be a viable option for single-tooth replacement. Keywords: bone-to-implant contact, custom implant, custom root-shaped implant, immediate loading, mineral apposition rate, REPLICATE Immediate Tooth Replacement System

Purpose: Irradiation results in deleterious effects on bone healing and integration of titanium implants. The impact of irradiation on osseointegration has been demonstrated in histologic studies, but the underlying molecular mechanisms have not been explored. This study aimed to investigate the effects of single-dose irradiation on the expression of biologic mediators crucial for inflammation, bone formation, and bone remodeling and to relate these molecular activities to implant stability after a 5-week healing period. Materials and Methods: A rat tibia model was used. An external single-dose irradiation of 20 Gy was administered to one leg while the second leg was used as a control. After 8 weeks, the irradiated and non-irradiated tibiae received titanium implants. Five weeks following implantation, implant stability was evaluated by removal torque measurement. Then, the implant and the bone surrounding the implant were retrieved for gene expression analysis of the implant-adherent cells and peri-implant bone, respectively. Results: Irradiation resulted in 55% reduction in removal torque. The implant-adherent cells in irradiated sites revealed downregulation of genes related to bone formation (ALP and OC) and upregulation of proinflammatory (TNF-α) and pro-fibrogenic (PDGF-b) genes. Conversely, the peri-implant bone in irradiated sites revealed upregulation of bone formation and bone remodeling genes. Removal torque showed a negative correlation with pro-inflammatory activity and a positive correlation with osteoblastic activity in the implantadherent cells. Conclusion: The impact of high (20 Gy) single-dose irradiation on osseointegration involves a reduction in bone formation activity and upregulation of pro-inflammatory and pro-fibrogenic activities in the implant-adherent cells. It is also suggested that this single-dose irradiation elicits a different molecular pattern at a distance from the implant surface, characterized by increased bone formation and remodeling activities in the peri-implant bone. Keywords: bone, gene expression, in vivo, irradiation, osseointegration, removal torque

Purpose: To determine differences in marginal bone changes when using submerged or transmucosal dental implants through a systematic review of the literature. Materials and Methods: PubMed, Embase, and the Cochrane Library were electronically searched for trials comparing marginal bone loss between submerged and transmucosal dental implants with a minimum follow-up of 12 months published between January 1980 and January 2016. Manual searches of the bibliographies of the included studies were also carried out. Screening of titles and abstracts, data extraction from the included studies, and quality assessment following the PRISMA statement were conducted in duplicate. Outcome measures were radiographic marginal bone level changes, implant survival, prosthesis failure, prosthetic complications, and esthetics. Results: The search strategy identified a total of 4,991 studies. Two of the authors independently screened 855 abstracts, resulting in a total of 12 studies; however, the total included in the systematic review was 11, as 2 studies were based on data from the same patients and were therefore counted as 1. A total of 998 implants (413 submerged and 585 transmucosal) were observed in 542 patients. Seven of the studies had a randomized study design and a follow-up of 12 months; therefore, they were included in the meta-analysis of bone loss and implant survival. The overall estimate of the bone loss difference was -0.01 mm (95% confidence interval [95% CI] -0.11 to 0.09 mm), and there was less bone loss in the transmucosal implants than in the submerged implants (P = .811, I2 = 63.7%). The estimated relative risk for implant loss at 12 months was 0.31 (0.09 to 1.09, P = .068, I2 = 0%) in favor of the submerged healing protocol. Augmentation procedures seemed to be successful irrespective of the implant placement modality, but owing to few clinical data no evidence could be found. Because of the lack of clinical data, esthetic outcomes could be reported only in a descriptive way. Conclusion: In the present meta-analysis, no evidence was found of differences between submerged and transmucosal implant placement protocols with regard to changes in marginal crestal bone levels or implant survival at 12 months follow-up. Therefore, it can be concluded that in many clinical situations it seems questionable whether a closed healing protocol offers an advantage over a transmucosal protocol. Keywords: bone loss, dental implants, meta-analysis, submerged, systematic review, transmucosal

Purpose: To study the relation between irretrievable abutment healing caps (AHCs), temperature, and the torque required to remove the AHCs from implants. Materials and Methods: Twenty implants, 13 mm long and 4.2 mm in diameter, were inserted into four acrylic boxes and covered with acrylic resin. An AHC was screwed into each implant, using a 30 N/cm torque. The acrylic blocks were placed in a 37°C water bath, and subsequently, a block was removed from the bath, the AHCs were cooled, and the torque needed to release each AHC from the implant was measured using a torque wrench. The cooling methods applied were contact with an ice cube for 10 or 25 seconds or spraying of endodontic refrigerant spray for 3 seconds. The control abutments were similarly tested, but without prior cooling. Results: The application of ice cubes for 10 seconds reduced the mean releasing torque from 29.60 ± 1.22 N/cm to 28.55 ± 1.96 N/cm (P = .01). Cooling the AHCs with ice cubes for 25 seconds reduced the mean required releasing torque from 29.6 N/cm to 27.85 ± 1.22 N/cm (P < .001). Cooling the same abutments using endodontic refrigerant spray for 3 seconds reduced the mean releasing torque to 27.74 ± 2.13 N/cm (P < .001). Conclusion: Within the limitations of this study, it is possible to conclude that cooling the AHC reduces the torque required for its release from the implant. This finding may also be relevant to the removal of prosthetic abutments with irretrievable screws. Keywords: cooling, implants, prosthetic abutments, torque

Purpose: The correlation between associated local factors and peri-implantitis remains unknown. The aim of this study was to investigate the association between the clinical and microbiologic profiles and periimplantitis to eventually categorize different groups of this disease. Materials and Methods: Subjects with at least one implant presenting signs of peri-implantitis were selected. The clinical, radiographic, occlusal, and microbiologic profiles of these infected implants were collected. Cases were classified into five peri-implantitis groups according to potential disease-triggering factors: surgically, prosthetically, biomechanically, purely plaque-associated, and a combination of them. Generalized estimating equations models were used to study differences among the potential risk factors. Cluster analyses were applied to investigate the correlation between clinical and microbiologic profiles and diseased implant samples. Results: Overall, 110 diseased and 121 healthy implants were included. The biomechanically associated group showed higher levels of microbiologic contamination inside the connection; however, the plaque-associated group had a higher level of microbial variety in the peri-implant sulcus. Cluster analyses demonstrated a significant ability to predict the associated factor of peri-implantitis. Moreover, radiographic marginal bone loss and implant width demonstrated the largest influence on the model. Conclusion: While peri-implantitis represents a plaqueinduced inflammatory condition, certain local factors might be associated with this biologic complication, as they imply plaque retention. Therefore, disease classification could be further implemented with the associated surgical, prosthetic, and biomechanical factors to better target the etiology. Keywords: associated risk factors, peri-implant disease, peri-implantitis

Purpose: The aims of this clinical study were to retrospectively evaluate implant survival, patient satisfaction, and radiographic, clinical, and esthetic outcomes following single-implant treatment. Materials and Methods: Eighty-seven patients, with a total of 126 implants (XiVE S, Dentsply Implants), who received single implant-retained crowns between 2004 and 2011 were retrospectively evaluated. Implant survival, marginal bone levels (MBL), changes in implant/mesial tooth vertical relationship, pink esthetic score (PES), white esthetic score (WES), patient assessment of the esthetics (visual analog scale), and oral health impact profile (OHIP-14) were evaluated. Results: Altogether, 59 patients with a total of 85 implants attended a final clinical and radiographic follow-up examination. The mean ages of males and females at implant placement were 19.78 and 22.58 years, respectively. The mean total follow-up time from the implant surgical date was 7.51 years. The 5-year implant clinical survival rate (CSR) was 98.4% (95% CI: 96.3%-100%), and crown CSR was 91.8% (95% CI: 86.3%-97.3%). The overall mean change in MBL was -0.19 mm. No significant differences were found between the different implant diameters (3.0, 3.4, and 3.8 mm) with regard to change in MBL. Mean increase in implant infraposition was 0.13 mm. With regard to esthetics, mean initial and final total PES were 9.61 and 11.49, respectively (P < .001). The mean WES was 6.48 at follow-up. Patients' mean assessment of soft tissue esthetics and implant-supported crown appearance were 73.5 and 82.1 (maximum score 100). At the follow-up examination, the additive OHIP-14 score was 16.11. Conclusion: This retrospective study of XiVE S implants found excellent survival rates and showed good clinical outcomes concerning patient-centered findings, esthetics, and marginal bone preservation. In context, it is important to stress that this study consisted of mostly young patients with agenesis who were treated by experienced clinicians. Keywords: agenesis, esthetics, infraposition, marginal bone level, patient satisfaction, patient-centered outcome, PES, pink esthetic score, single implant, WES, white esthetic score

Purpose: The aim of this study was to analyze the reliability of cone beam computed tomography (CBCT) in assessing the grayscale density (GSD) of bone by comparing it with microcomputed tomography (μ-CT) data. Materials and Methods: A total of 50 subjects with lost mandibular molars were included in the study. To assess the bone GSD, a previously fabricated template made of acrylic resin with a 2-mm-diameter metal rod was positioned, and CBCT was performed. The bone biopsies for μ-CT analysis were then obtained during implant surgery. The relationship between GSD assessed by CBCT and data from μ-CT analysis was studied using Spearman's rank correlation. Results: A total of 38 biopsies were available for μ-CT analysis. Positive correlations were identified between GSD and bone volumetric fraction (BV/TV) (r = 0.835, P < .001), bone volume (BV) (r = 0.353, P = .030), trabecular spacing (Tb.Sp) (r = -0.535, P = .001), and mean total volume (TV) (r = 0.470, P = .003). There was a clear positive linear correlation between normal values of GSD (< 700) and BV (r = 0.545). Conclusion: This study demonstrated the correlation between GSD assessed by CBCT and bone density assessed by μ-CT in the posterior mandible. For areas of typical bone density, there seems to be a positive linear correlation between GSD assessed by CBCT and bone density assessed by μ-CT. Keywords: alveolar bone, complication, cone beam computed tomography, dental implant, diagnostic imaging, endosseous implant

Purpose: To assess outcomes of treating completely edentulous patients with a fixed implant-supported profile prosthesis, utilizing a graftless approach, for the maxilla and for the mandible, with an emphasis on patientrelated outcomes, specifically maximum occlusal force, patient satisfaction, and impact on quality of life. Materials and Methods: This was a cross-sectional study with the following inclusion criteria: completely edentulous patients rehabilitated with a fixed implant-supported profile denture, utilizing a graftless approach. Patients fulfilling the inclusion criteria were asked to participate in the study during their follow-up visits; hence, a consecutive sampling strategy was used. To measure maximum occlusal force, a digital occlusal force gauge was used. Subjects were asked to answer a paper survey distributed in the clinic. The survey contained general demographic questions, visual analog scale (VAS) categories, and Oral Health Impact Profile-14 (OHIP-14). Results: The mean VAS score was 8.9 out of a possible 10. The mean OHIP-14 score was 7.5 out of a possible 56. The mean maximum occlusal force recorded in the anterior region was 108 Ncm. The mean maximum occlusal force recorded in the posterior region was 205 Ncm. Conclusion: Results indicated that patients treated with a graftless approach reported high satisfaction and impact on quality of life. Regarding maximum occlusal force values, significant differences between men and women were reported. The impact on quality of life seemed to improve when patients presented completely edentulous at the time of treatment as opposed to terminal dentition. Finally, significant positive correlations were detected between satisfaction and impact on quality of life, impact on quality of life and posterior maximum occlusal force, anterior and posterior maximum occlusal force, and complications and anterior maximum occlusal force. Keywords: All-on-4, graftless, hybrid, impact on quality of life, maximum occlusal force, patient satisfaction, profile prosthesis, tilted implants, zygoma

Purpose: To evaluate long-term survival rates and radiographic stability of sinus floor elevations carried out using a two-layer grafting technique. Materials and Methods: Records were analyzed for patients treated with sinus floor elevations using a modified technique. Phycogenic hydroxyapatite (Algipore, Dentsply Sirona Implants) and autogenous bone particles harvested from intraoral sites were grafted in two distinct layers after elevation of the sinus mucosae. In this approach, the basal part of the sinus floor is grafted with autogenous bone, while the cranial part is grafted with the phycogenic hydroxyapatite. In some cases, implants were placed simultaneously, such that the entire surface of each implant was covered by autogenous bone particles. A titanium membrane was used to close the sinus window, and the implants were loaded 3 months later. In two-stage approaches, the implants were inserted 3 to 4 months after the grafting and loaded after 3 additional months. Panoramic radiographs were taken after the grafting procedure, after implant insertion, after the prosthetic restoration, and then annually for 10 years. These radiographs were used to measure the height between the implant shoulders and the top of the graft. Results: Of the 214 sinus floor elevations performed on 129 patients using the bilayering technique, 198 procedures in 118 patients were included in the study (136 one-stage and 62 two-stage). Membrane perforations during surgery occurred in 17.9% of the procedures and were sutured and sealed with fibrin glue. A total of 487 implants were placed in the grafted areas. No severe postoperative complications occurred, but three implants were lost throughout the 10-year follow-up period. A small decrease of vertical height was observed between the grafting surgery and the stage-two surgery (mean: 1.8 mm). After that, no bone height was lost over the 10 years. Conclusion: The layer grafting technique in combination with sinus floor elevation resulted in radiographically stable vertical bone height for 10 years. This technique enabled early placement and loading of implants in the grafted areas. The survival rate obtained with this procedure is similar to that expected for implants placed in nongrafted areas. Keywords: Algipore, autogenous bone, bilayer technique, biomaterial, bone augmentation, graft stability, sinus floor elevation

Purpose: To investigate the association between the intake of proton pump inhibitors (PPIs) and the risk of dental implant failure. Materials and Methods: The present retrospective cohort study is based on patients consecutively treated between 1980 and 2014 with implant-supported/retained prostheses at one specialist clinic. Modern endosseous dental implants with cylindrical or conical design were included, and only complete cases were considered; ie, only those implants with information available for all variables measured were included in the regression model analysis. Zygomatic implants and implants detected in radiographies but without basic information about them in the patients' files were excluded from the study. Implant- and patient-related data were collected. Multilevel mixed-effects parametric survival analysis was used to test the association between PPI exposure (predictor variable) and risk of implant failure (outcome variable), adjusting for several potential confounders. Results: A total of 3,559 implants were placed in 999 patients, with 178 implants reported as failures. The implant failure rates were 12.0% (30/250) for PPI users and 4.5% (148/3,309) for nonusers. A total of 45 out of 178 (25.3%) failed implants were lost up to abutment connection (6 in PPI users, 39 in nonusers), with an early-to-late failure ratio of 0.34:1. The intake of PPIs was shown to have a statistically significant negative effect for implant survival rate (HR 2.811; 95% CI: 1.139 to 6.937; P = .025). Bruxism, smoking, implant length, prophylactic antibiotic regimen, and implant location were also identified as factors with a statistically significant effect on the implant survival rate. Conclusion: This study suggests that the intake of PPIs may be associated with an increased risk of dental implant failure. Keywords: dental implant, failure, multilevel mixed effects parametric survival analysis, multivariate analysis, proton pump inhibitors, risk factors

Purpose: The aim of this study was to compare the complication rates of recipient sites prepared using two incision techniques: crestal and tunnel. Materials and Methods: In this prospective study, patients underwent augmentation procedures (68 patients; 75 sites) by the same surgeon that were performed consecutively using the crestal incision technique (27 horizontal, 10 vertical; crestal group) or the tunnel incision technique (27 horizontal, 11 vertical; tunnel group). Autogenous bone block grafts were harvested with a piezoelectric surgical device, and the grafts were fixed at the recipient sites by two titanium screws in both groups. The authors evaluated minor exposure, transient paresthesia, major exposure, permanent paresthesia, gingival recession at adjacent teeth, surgery time, and visual analog scale pain scores. Results: Soft tissue dehiscence and graft failure were significantly lower in patients undergoing the tunnel technique. Conclusion: The tunnel incision technique significantly decreased soft tissue exposure, the most common complication of augmentation procedures with autogenous onlay bone grafts. This technique should be considered an alternative to the crestal incision technique for preparation of the recipient site. Keywords: alveolar ridge augmentation, autogenous bone, complication, failure, minimally invasive surgery, subperiosteal tunnel technique

Purpose: The aim of this study was to evaluate the influence of the implant diameter on marginal bone remodeling around dental implants replacing single molars after a follow-up period of 3 to 6 years. Materials and Methods: Patients who received dental implants with an external hexagon platform in healed sites to support a single metal-ceramic crown in the molar region were recalled to the office. The implantation sites and implant length information were recorded, and the implants were divided according to the implant diameter: regular (RP) or wide (WP). Each implant was assessed by digital periapical radiography, using a sensor holder for the paralleling technique. The marginal bone remodeling was determined as the distance from the implant platform to the first bone-to-implant contact, and the known implant length was used to calibrate the images in the computer software. The follow-up measurements were compared with those obtained from the radiograph taken at the time of prosthetic loading to determine the late bone remodeling. The independent t test was used to compare data. Results: A total of 67 implants from 46 patients were evaluated with a mean follow-up period of 4.5 ± 1.0 years. The RP group comprised 36 implants from 29 patients (mean age: 58.3 ± 10.6 years), while 31 implants from 17 patients (mean age: 56.9 ± 11.5 years) were included in the WP group. The RP group presented lower survival rates (86.1%) than the WP group (100.0%). Similar marginal bone loss (P < .05) was identified for the RP and WP groups (1.35 ± 0.96 mm and 1.06 ± 0.70 mm, respectively). Conclusion: Although wide-diameter implants exhibited lower incidence failures, the bone levels were similar after the prosthetic loading around regular- and wide-diameter implants supporting single molar crowns. Keywords: bone loss, dental implants, osseointegration

Purpose: To describe the clinical outcomes and complications related to provisional prostheses after fullarch implant-supported rehabilitation by means of an immediate loading protocol. Materials and Methods: This retrospective cohort study included patients who were consecutively treated with full-arch implantsupported restorations with a minimum of four implants (Replace Select Tapered TiUnite, Nobel Biocare AB) per arch and conical abutments (multi-unit, Nobel Biocare AB) by means of an immediate loading protocol. The surgical procedures were performed between May 2006 and June 2014 by a single oral surgeon. Demographic, surgical, and prosthetic variables were collected, and biologic and mechanical complications were registered. Results: A total of 61 maxillae (57%) and 46 mandibles (43%) were treated in 88 patients (40 men and 48 women) with a mean age of 62.4 years. A total of 558 implants were placed, 295 in postextraction sockets. A total of 331 implants (59.3%) were placed in the maxilla and 227 (40.7%) in the mandible. Within a 9-month period, 18 prostheses (16.8%) fractured (15 maxillary and 3 mandibular); in nine of these patients the opposing dentition was a full-arch, implant-supported restoration, and in the remaining nine patients, it was natural dentition. Six (1.1%) maxillary and three (0.5%) mandibular implants failed. Conclusions: A high implant survival rate is expected in the short term following this immediate loading protocol. Fracture of the provisional prosthesis is a common finding, affecting 17% of patients, and is significantly more prevalent in patients with bruxism and in maxillary prostheses. Keywords: complications, full-arch fixed prosthesis, hopeless teeth, immediate implants, immediate loading

Purpose: The purpose of this study was to clinically evaluate the screwless Morse taper implant-abutment connection type, in which the retention screw is totally eliminated, in terms of stability, success, periodontal parameters, and marginal bone levels after 1 year of function by comparing it with a passive fit internal implantabutment connection, wherein a space exists between the matching components. Materials and Methods: Each edentulous subject received an implant with a screwless Morse taper connection (MT) in the left canine area of the mandible and an implant with a screw-retained implant-abutment connection (SR) in the right canine area of the mandible. All implants were loaded 6 weeks later. All cases were restored with a cemented bar-retained mandibular overdenture opposing a maxillary complete denture. Clinical recalls at 6 months and 12 months postloading were scheduled and the MT and SR implants were compared in terms of success, survival, primary and secondary implant stability, marginal bone loss, soft tissue response, and mechanical complications. The results were statistically analyzed. Results: A total of 20 subjects were included (10 females, 10 males; average age: 61.60 years) and a total of 40 implants were inserted. No implant failure or technical problem was detected for either MT or SR implants. Marginal bone loss around MT and SR implants did not show any significant differences at 6 weeks after surgery (time of loading) or at 6 months or 12 months postloading (P > .05). Periodontal parameters such as gingival index and probing pocket depth of MT and SR implants likewise did not differ significantly at 6 months and 12 months postloading (P > .05). Primary stability values of MT and SR implants did not differ significantly when measured with the insertion torque device (mean of 68.10 Ncm for MT and 64.20 Ncm for SR implants; P = .564), nor when measured with the electronic percussive testing device (mean of −5.30 for the MT and −5.35 for the SR implants; P = .398). However, MT implants showed lower stability at the time of loading (6 weeks) and 6 months postloading (P = .037 and P = .003, respectively). Stability values did not show any significant differences 12 months postloading (P > .05). Conclusions: Within the limitations of this clinical study, it can be concluded that implants with screwless Morse taper and passive fit internal connections show comparable technical and biologic results after 1 year of function. Keywords: dental implant, Morse taper, screwless Morse taper

The aim of this article is to describe the procedure for sealing the screw access channel using plastic tape, polytetrafluoroethylene, in screw- or cement-retained implant-supported prostheses. This technique is viable and easily performed, and the functional and esthetic results are satisfactory. Keywords: cement retention, dental implants, implant-supported prosthesis, polytetrafluoroethylene, screw retention

Purpose: To evaluate prospectively the behavior of narrow-diameter (3.3-mm) titanium-zirconium alloy implants with a hydrophilic surface (Straumann Roxolid SLActive) in patients with type 2 diabetes mellitus in single-unit restorations, compared with a healthy control group (assessed using the glycosylated hemoglobin HbA1c test). Materials and Methods: The patients evaluated in this study required single-unit implant treatment; 15 patients had type 2 diabetes mellitus, and 14 patients were healthy (control group [CG]). Marginal bone level (MBL) change around the implants was evaluated using conventional, sequential periapical digital radiographs. Patient HbA1c was assessed in each check-up. Normality test (Kolmogorov- Smirnov), univariate and multivariate logistic regression, analysis of variance (ANOVA), and Mann-Whitney U test were used for statistical analysis. Results: No differences in MBL change and implant survival and success rates were found between the diabetes mellitus group (DMG) versus the control group, either during the initial recording (DMG, 0.99 ± 0.56 vs CG, 0.68 ± 0.54; P > .05) or 6 months after restoration (DMG, 1.28 ± 0.38 vs CG, 1.11 ± 0.59; P > .05). No significant correlation between HbA1c levels and MBL change was detected in these patients (P > .05). Conclusion: Patients with glycemic control exhibit similar outcomes to healthy individuals with regard to the investigated parameters. In light of these findings, the titaniumzirconium alloy small-diameter implants can be used in the anterior region of the mouth in type 2 diabetic patients. Keywords: glycosylated hemoglobin, small-diameter implants, titanium-zirconium implants, type 2 diabetes

Purpose: The primary objective of this prospective cohort study was to evaluate primary and secondary implant stability values of implants placed into healed free fibula-reconstructed mandibles. The secondary objective was to investigate whether a correlation existed between primary implant stability and the quantity of cortical bone-implant contact and of cortical fibular bone in contact with the implants. Materials and Methods: The study participants are patients enrolled in a registered trial (No. CTRI/2012/07/002764). Patients with healed segmental mandibular reconstruction by means of free fibula flaps were chosen to undergo implant-supported dental rehabilitation. Preoperatively, computed tomography (CT) scans were used to measure the quality (density) of bone in Hounsfield units (HU). Implant stability quotients (ISQ) were obtained at the time of implant placement (primary), as well as 6 months later (secondary). The amount of cortical bone-to-implant contact (CBIC) was measured from postoperative panoramic radiographs using image analysis software (Image J). A paired t test was used to compare the mean primary and secondary ISQ values. Pearson correlation was used to determine the relationship between primary ISQ and CBIC. Statistical significance was set at the 5% level (P < .05). Results: Of 54 patients (156 implants) who were enrolled, 35 (104 implants) were assessed. The reasons for exclusion were as follows: 11 patients (34 implants) had inadequate preoperative CT documentation, 7 patients (16 implants) had unreadable panoramic radiographs, and 1 patient (2 implants) had partial necrosis of the flap. The mean primary and secondary ISQ values were 78.1 (SD = 4.3) and 77.8 (SD = 4.6), respectively (P = .348). The mean density of cortical fibula bone was 1,344 HU (SD = 93.6). The mean CBIC was 3.7 mm (SD = 1.4). The study results showed a positive correlation between CBIC and implant stability (r = 0.274, P = .005). Conclusion: This study showed no differences in primary and secondary ISQ values of implants placed into the fibula. Implant stability quotients correlated positively with CBIC. Keywords: bone density, bone quality, dental rehabilitation, free fibula flap, implant stability, mandible reconstruction, removable prosthodontics, resonance frequency

Purpose: Outcome research has become an increasingly important form of clinical evidence for making health care decisions, including oral health considerations in the field of dentistry. In oral reconstruction involving dental implants, the risk of implant failure may be influenced by a patient's underlying medical condition. To identify associations, implant failure and systemic conditions or diseases were studied in a consecutive series of patients who received dental implants from October 1, 1983, to December 31, 2014, in the Department of Dental Specialties at Mayo Clinic in Rochester, Minnesota. Materials and Methods: Data were abstracted from a prospective clinical database and electronic health records for patients' demographic, implant-specific, and medical profiles to determine time to first implant failure. Survival free of implant failure at the patient level was estimated by using the Kaplan-Meier method. Associations of demographic and systemic characteristics with implant failure were evaluated by using Cox proportional hazards regression models and summarized with hazard ratios and 95% confidence intervals. Results: The patient cohort consisted of 6,358 patients with a median age of 53 years at placement of the first implant. A total of 713 patients experienced implant failure at a median of 0.6 years. Among the 5,645 patients who did not experience implant failure, the median duration of follow-up was 5.8 years. More than 20 systemic diseases or conditions were identified for assessment, of which 15 comprised more than 50 patients and five comprised more than 500 patients. All associations were adjusted for age, sex, and era of implant, given the strong influence of these features on implant failure. After adjustment, no systemic disease or condition was shown to increase the risk for implant failure in the population and setting studied. Conclusion: Patients considering oral reconstruction involving implants in the medical setting studied do not appear to risk implant loss because of systemic conditions or diseases. Keywords: association, implant failure, patient-based, systemic condition, systemic disease

Purpose: To report survival rate, early surgical template-related complications, and prevalence of periimplantitis of dental implants placed in private practices using computer-guided, template-assisted surgery and followed between 1 and 10 years. Materials and Methods: The present retrospective multicenter study evaluated data collected from fully or partially edentulous patients, with anodized-surface implants placed using computer-guided, template-assisted surgery between January 2006 and December 2015. The outcome measures were implant cumulative survival rate (CSR), early surgical complications involving the surgical template, and prevalence of peri-implantitis. Results: A total of 694 implants were placed in 141 patients. Ten patients (7.1%) with 48 implants (6.9%) dropped out during the study period. One hundred seventeen patients, who received 121 surgical and prosthetic procedures, were treated according to a double-scan protocol, while the remaining 24 patients were treated by using the integrated treatment workflow. Most of the implants were immediately loaded (528 implants, 76.1%; 112 patients, 79.4%). Overall, 107 complete full-arch restorations (supported by four to eight implants each) were delivered in 103 patients (73%) with 595 implants (85.7%), while 13 single and 30 partial restorations (two to five implants each) were delivered in 38 patients (27%) with 99 implants (14.3%). Patients were followed for up to 10 years (mean: 58.2 months, range: 12 to 120 months). Implant- and patient-level CSR (Kaplan-Meier estimation) at the 10-year follow-up was 97.4% (95% CI: 1.0309 to 0.9161) and 92.1% (95% CI: 1.1575 to 0.6836), respectively. All failed implants were lost before definitive prosthesis delivery (early failure). Ten (7.1%) minor template-related complications were experienced and resolved chairside. Over the entire follow-up period, four patients (2.8%) with 12 implants (1.7%) showed signs of peri-implantitis at the 1- (four implants), 2- (four implants), and 4-year (four implants) visits. Conclusion: High long-term survival rates and low complications and prevalence of peri-implantitis were observed for a large cohort of anodized-surface implants placed in private practices. Further studies are needed to confirm these preliminary results. Keywords: computer-guided implant surgery, dental implants, immediate loading

Purpose: To compare the Encode impression protocol (Biomet 3i) with the conventional impression protocol in terms of treatment duration, clinical accuracy, and outcome up to the first postplacement review of singleimplant crowns. Materials and Methods: A total of 45 implants were included in this study. The implants were randomly allocated to the Encode group (23 implants) or the conventional group (22 implants). At the time of surgery, all implants received two-piece Encode healing abutments. The implants were restored 3 months after insertion. In the conventional protocol, open-tray implant-level impressions were taken and the implants were restored with prefabricated abutments and porcelain-fused-to-metal (PFM) crowns. For the implants in the Encode group, closed-tray impressions of the healing abutments were taken. The generated casts were sent to the Biomet 3i scanning/milling center for custom abutment manufacturing on which PFM crowns were fabricated. Treatment duration (laboratory and clinical), clinical accuracy of occlusal and proximal contacts, and outcome (esthetics, patient satisfaction, and crown contour) were evaluated with the aid of a series of questionnaires. Results: The Encode protocol required significantly less laboratory time (18 minutes) than the conventional protocol for adjustment of the abutments. The impression pour time, time for the laboratory to return the crown, time for crown insertion at the final appointment, and total clinical time for crown insertion did not differ significantly between the two protocols. Likewise, clinical accuracy, esthetics, and patient satisfaction were similar for the two protocols. Conclusion: The two protocols were clinically comparable. The Encode protocol is advantageous in reducing the laboratory time before crown fabrication. Keywords: abutment, CAD/CAM, Encode, implant impressions, laboratory procedures

Purpose: To investigate whether polymorphisms of cluster of differentiation 14 (CD14), tumor necrosis factor alpha (TNFα), interleukin (IL)6, IL10, and IL1ra genes are associated with the risk of peri-implantitis susceptibility in patients with dental implants in the Serbian population. Materials and Methods: Isolated DNA from the blood was used for IL10-1082, TNFα-308, IL6-174, CD14-159, and interleukin 1 receptor antagonist (IL1ra) genotyping using polymerase chain reaction (PCR)-based methodology. Clinical parameters included: peri-implant pocket depth (PPD), Plaque Index (PI), Gingival Index (GI), bleeding on probing (BOP), and radiologic bone loss. Results: The study included 98 patients with dental implants in function for at least 1 year, divided into peri-implantitis (34) and healthy peri-implant tissue (64) groups. The percentage distribution of smokers was significantly different between patients who developed periimplantitis and patients with healthy peri-implant tissue (71% vs 42%, respectively) and associated with increased peri-implantitis risk (OR: 3.289, 95% CI: 1.352 to 8.001; P = .007). A positive history of periodontitis was more frequent in the peri-implantitis group (62%) than in the healthy peri-implant tissue (20%) group and associated with increased peri-implantitis risk (OR: 6.337, 95% CI: 2.522 to 15.927; P = .0001). Frequencies of CD14-159, TNFα-308, IL10-1082, and IL6-174 genotypes were significantly different between patients with and without peri-implantitis. However, logistic regression revealed only TNFα-308 polymorphic GA/AA genotypes (OR: 8.890, 95% CI: 2.15 to 36.7; P = .003) and smoking (OR: 6.2, 95% CI: 1.44 to 26.7; P = .014) as independent factors associated with increased peri-implantitis risk, while CD14-159 polymorphic CT/ TT genotypes were associated with decreased risk for peri-implantitis (OR: 0.059, 95% CI: 0.009 to 0.355; P = .002). Conclusion: The findings suggest that smoking and the presence of TNFα-308 GA/AA genotypes may increase the risk for peri-implantitis, while CD14-159 polymorphic CT/TT genotypes decrease the risk. The results also indicate significant association of CD14-159, TNFα-308, and IL6-174 genotypes and clinical parameters in the Serbian population. However, future studies in larger patient groups are necessary to confirm these observations. Keywords: cytokines, genetic polymorphism, inflammation, peri-implantitis

Purpose: To evaluate the biochemical composition of bone nodules deposited by gingival mesenchymal stem cells (GMSCs) over titanium machined surfaces in vitro. Materials and Methods: GMSCs were isolated from healthy gingival tissues of patients undergoing crown-lengthening surgical procedures. GMSCs were characterized following the International Society for Cellular Therapy guidelines. After incubation of the GMSCs with titanium discs, osteogenic differentiation was induced for 28 days. Osteogenic lineage was confirmed by means of Alizarin Red S staining. Bone nodule morphology and deposition by GMSCs were characterized by scanning electron microscopy (SEM). An elemental analysis of the bone nodules was done using energy-dispersive x-ray spectroscopy (EDS). The biochemical composition of these nodules was further characterized via Raman spectroscopy, with native alveolar bone used as a control. Results: GMSCs adhered and proliferated on the titanium discs and exhibited a spindle-shaped fibroblast-like morphology under standard culture conditions. Their phenotype was confirmed by the expression of CD105, CD90, CD73, and CD146, observed using flow cytometry. Deposits of calcium bone nodules were evident in the cultures after staining with Alizarin Red S, but were absent in the controls. Calcium and phosphate, the major components of hydroxyapatite, were present in the bone nodules, as shown by means of the EDS analysis. The results obtained from Raman spectra of these nodules showed the phosphate ions (ν[PO4 3-], ~960 cm1), amide III (δ[NH], ~1,245 cm-1), CH2 scissors (~1,451 cm-1), amide I (ν[C = O], ~1,667 cm-1), and ν(CH) (2,800-3,100 cm-1) bands were similar to those observed in native bone. Conclusion: GMSCs can deposit a bone-like mineral highly similar to native bone (HA) over titanium surfaces. Ongoing studies are aimed at determining whether GMSCs can deposit a similar bone matrix/tissue over removed failed dental implants. If HA can be placed over removed failed dental implants, it may be possible to re-osseointegrate dental implants that are failing as a result of peri-implantitis in vivo. Keywords: mesenchymal stem cells, osseointegration, peri-implantitis, regeneration, tissue engineering