The International Journal of Oral & Maxillofacial Implants, 02/2021

Purpose: Early implant failures have been observed in dental implant treatments even when the procedures are performed under appropriate conditions and in patients without local or systemic contraindications, suggesting that an intrinsic component of the patient could modify the osseointegration process. The objective of this systematic review was to analyze the association between early implant failure and genetic polymorphisms. Materials and methods: A systematic search was performed in the PubMed, ScienceDirect, and Scopus databases using the PRISMA statement as the main guidelines and "Dental implant" AND "Polymorphism" as search terms. The search cutoff date was August 2019. In addition, the risk of bias, methodologic quality, and heterogeneity of the included studies were analyzed. Results: The search strategy yielded 225 articles, and the titles and abstracts were reviewed to evaluate if they were relevant to the subject. Twenty-four articles were selected for a complete reading, of which 10 articles met the inclusion criteria. Finally, five studies citing the association of the following polymorphisms with early implant failure were chosen: G-1607GG of the MMP 1 gene, C-799T of the MMP 8 gene, and -77 A>G of the gene MMP 13. Conclusion: The polymorphisms analyzed are from the promoter region, generating altered cellular transcriptional activity for MMP 1, MMP 8, and MMP 13, the effects of which are observed in inflammation and extracellular matrix degradation. Establishing a relationship between genetic polymorphisms and phenomena such as early implant loss is necessary for the development of precision medicine in the field of dentistry. Keywords: dental implant, early implant failure, genetic polymorphism

Purpose: The aim of this study was to evaluate the precision of fit of bar frameworks fabricated using three different production processes and the effect of changes in the CAD/CAM process steps on the precision of the resulting bar frameworks. Materials and methods: Four implants were applied to a mandibular phantom model, and three different production techniques were used to fabricate 30 bar frameworks. In the first group, the bar frameworks were fabricated with the conventional production process (the lost-wax technique; n = 10). In the second group, a CAD/CAM production process was used with digital data collected individually from the master model for the production of each of the final bar specimens (n = 10). In the third group, a CAD/CAM production process was used with the master model being scanned once, and the single resulting data value was used for the production of all final bar specimens (n = 10). The marginal gap between bar frameworks and implants was digitally calculated (ATOS So High-End 3D Digitizer for Small Objects, GOM Inspect). Newman-Keuls multiple comparison tests, a Tukey multiple comparison test, and Pearson correlation tests were applied to the data with a level of significance of P < .05. Results: The mean marginal gap value of group 1 was 95.25 ± 76.15 μm, which was statistically significantly lower than the other groups (P = .0001). For group 2, the mean marginal gap value was 152.00 ± 97.19 μm, whereas for group 3, the mean marginal gap value was 156.7 ± 78.70 μm. Among group 2 and group 3, no statistically significant difference was observed at the mean marginal gap value. Conclusion: The marginal gap values in the CAD/CAM bar framework groups were significantly higher than the conventional bar framework group. Among the CAD/CAM groups, the mean marginal gap values were not statistically significant. Keywords: CAD/CAM, conventional production technique, passive fit

Purpose: Bone graft materials and soft tissue allografts are widely used in clinical practice to counteract physiologic postextraction site tridimensional shrinkage. The aim of this study was to test if plasma of argon treatment could have a bioactivation effect on hard and soft tissue scaffolds in clinical usage. Materials and methods: Forty-eight bovine bone matrix and porcine collagen samples were subdivided into two groups (test and control) of 12 samples each. The test group was treated with argon plasma (10 W, 1 bar for 12 minutes), while the control group was left untreated. Immediate cell adhesion and a proliferation assay at 72 hours were performed in the perfusion chamber of a bioreactor. Additionally, micro-CT analysis was performed on the treated and untreated scaffolds, before and after soaking in cell culture medium (four samples). Results: Osteoblasts seeded on plasma-treated bone matrix significantly increased the adhesion level compared with the untreated sample (43,144.3 ± 12,442.9 vs 21,736 ± 77,27.1; P = .0083). However, 3-day proliferation tests could not achieve significant differences between groups (105,715.5 ± 21,751.5 vs 107,108.6 ± 19,343.4; P = .998). No differences were measured on fibroblast adhesion on the collagen matrix in both conditions. Plasma of argon treatment and soaking in cell culture medium did not affect the bone matrix samples. The structure of collagen matrix samples was unaltered after plasma treatment, but became enlarged after soaking. Conclusion: Plasma of argon may be useful to biofunctionalize bone grafts, although benefits seemed to disappear after 3 days. No biologic response was detected on collagen matrix scaffolds. In vivo studies are needed to draw final clinical conclusions. Keywords: biomaterials, bone graft, bone substitute, guided bone regeneration, surface

Purpose: Dental implant placement is often followed by acute pain, which is one of the most important patient-centered matters of treatment. However, this pain is often not adequately appreciated by clinicians, and knowledge about risk factors associated with acute pain is scant. An understanding of these factors is important to help clinicians deliver efficient pain control advice based on individual demand. Materials and methods: A systematic review of the literature was carried out to identify published risk factors for acute pain after dental implant surgery. PubMed, Cochrane Central Register of Controlled Trials, Embase, and Google Scholar databases were searched to find pertinent studies up to August 2019. Cohorts and randomized controlled trials (RCTs; including split-mouth trials) were included. The criteria used were those described in the PRISMA statement for performing systematic reviews. Results: Nine hundred twenty-five papers were identified through the initial searching. After three stages of screening, 38 articles were included in the qualitative analysis but only 8 in the quantitative analysis. Despite the heterogeneity of the included articles, these data showed that flapped (vs flapless) surgery, anxiety, longer surgical duration, anticipation of more pain before surgery, and higher pain levels at earlier time points play a key role in the intensity of acute pain after dental implant surgery. There is strong evidence to suggest that the place of insertion (maxilla/mandible) is not a risk factor for pain. Conclusion: The results for the effect of immediate loading (vs delayed loading), number of implants inserted, sex, age, and smoking on pain were inconclusive. Keywords: dental implants, meta-analysis, postoperative pain, risk factor, systematic review

Purpose: Assessment of in vitro efficacy of three different nonsurgical implant surface decontamination methods in three peri-implant bone defect simulation models. Materials and methods: A total of 180 implants were allocated to differently angulated (30, 60, and 90 degrees) peri-implant bone defect resin models, each covered by a mucosa mask. All implants were stained with indelible red color and assigned to one of the three defect models. In each simulated bone defect group, 20 implants were decontaminated for 2 minutes with a curette (CUR), sonic scaler (SOSC), or air-powder abrasion device (APA) with glycine powder. Photos were taken from both sides of each implant to measure the percentage of uncleaned implant surface area. Scanning electron microscopy (SEM) was used to assess the implant surface for morphologic damage. Results: Among the three defect angulations, a significantly different cleaning efficacy (P < .001) for each treatment method was found (30 degrees: CUR [67.33%], SOSC [62.70%], APA [39.33%]; 60 degrees: CUR [61.59%], SOSC [54.31%], APA [23.91%]; 90 degrees: CUR [66.82%], SOSC [55.77%], APA [28.03%]). SEM did not show any considerable surface damage after APA treatment in comparison with after CUR or SOSC. Conclusion: Air-powder abrasion proved to be the most efficient nonsurgical treatment device for each type of defect in this in vitro model with the least noticeable surface change. No decontamination method resulted in complete cleaning of the color remnants on the implant surface. Keywords: abrasion, decontamination, dental air, dental implant, peri-implantitis

Purpose: Implant overdentures with splinted attachments have been used in clinical practice, and the effect of splinting on implants has been reported frequently. However, the effect of implant configuration of more than four implants and covering the palate with an overdenture has not been sufficiently examined. The purpose of this study was to reveal the effects of implant configuration and palatal coverage on both implant and denture strain in maxillary implant overdentures using splinted implants. Materials and methods: Six implants were placed in the anterior, premolar, and molar areas in a maxillary edentulous model. Four strain gauges were attached to the implant surface, and Dolder bar attachments were used to splint implants distributed in various configurations. Two types of maxillary experimental dentures (with/without palatal coverage) were fabricated, and two strain gauges were attached at the midline. A vertical load of 98 N was applied, and the strains on the dentures and implants were measured. The strain measurements were compared using one-way analysis of variance and t test (P = .05). Results: When comparing the implant strains, the strain was significantly smaller on the anterior and premolar implants when six implants were used, but there was no significant difference among the different implant configurations in the strain on the molar implants. Strains on anterior implants of the palateless overdenture were significantly greater than those of the overdenture with palatal coverage. When four implants were used, the strain on the palatal side of dentures without palate was significantly greater than that on those with palatal coverage. When six implants were used, there was no significant difference in the strain on either side between two types of dentures. Conclusion: When implants were splinted to each other using a denture without palatal coverage, the strain of dentures when six or two anterior and two posterior implants were used was lower. The difference of denture strains between two types of dentures was not significant when six implants were used, but was significant for all other configurations. Also, the difference of implant strains between two dentures was significant in anterior implants regardless of implant configuration. Keywords: bar attachment, implant configuration, maxillary implant overdenture, palateless denture, splinted implants, strain

Purpose: The objective of this study was to evaluate the influence of the oxide layer removal procedure using acid on the roughness and internal fit of overcast universal castable long abutments (UCLAs) for a taper connection. Materials and methods: For this, maxillary first premolars were waxed on the plastic sleeve of 15 UCLAs with a premachined interface. The specimens were overcast using the NiCr alloy, and the frameworks were randomly distributed to undergo one of two different oxide layer removal methods: blasting with 100-μm particles of aluminum oxide at 0.60-MPa pressure or bathing for 5 hours in 0.5% hydrofluoric acid. The surface roughness was evaluated by a light interferometer at the subcritical contour of each abutment. Next, the frameworks were attached to the respective analogs for internal fit evaluation. The central cross section of each assembly was exposed, and three regions were visualized by scanning electron microscopy (SEM): taper interface, axial wall, and index region. The premachined base was used as the control. The groups were compared using analysis of variance (ANOVA) and Tukey post hoc test (α = .05). Results: The results showed that acid bathing produced intermediary roughness between premachined and blasted surfaces (P < .05). SEM images showed a sealed interface at the taper region of all groups, despite some irregularities after alumina blasting. Increased discrepancies at the axial wall and index region were found after the alumina blasting procedure (P < .05). Conclusion: It was concluded that acid bathing should be used, instead of blasting to remove the oxide layer, to produce a better fit and smoother surface on UCLAs. Keywords: abutment, internal connection, prosthetic procedure, surface

Purpose: The aim of this study was to explore the influence of different bone grafts, demineralized freeze-dried bone allograft (DFDBA, OraGraft), and deproteinized bovine bone mineral (DBBM, Bio-Oss) implanted in mouse calvaria defects on gene expression. Materials and methods: Male C57BL/6MLac mice were separated into three groups as follows: group 1-defect without graft as control, group 2-DFDBA, and group 3-DBBM. Affymetrix DNA microarrays were used to characterize gene expression in bone after 3 months of graft healing. Differential expression of designated genes discovered by microarray analysis was confirmed using real-time polymerase chain reaction (PCR) and immunohistochemistry. Results: Compared with normal bone healing, 355 and 1,108 coding genes of bone grafted with DFDBA were upregulated and downregulated, respectively. The upregulated genes were mainly involved in chemokine signaling, macrophage activity, osteoclast activity, cytokine expression, T-cell receptor signaling, apoptosis, and MAPK signaling. The downregulated genes were predominantly involved in calcium regulation in cardiac cells, chemokine signaling, MAPK signaling, and adipogenesis. A total of 306 and 817 coding genes of bone grafted with DBBM were upregulated and downregulated, respectively. The upregulated genes were mainly involved in osteoclast activity, chemokine signaling, B cell receptor signaling, macrophage activity, and signaling of T-cell receptor, MAPK, IL-5, and IL-1. The downregulated genes were predominantly involved in calcium regulation in the cardiac cell and osteoclast activity. Real-time PCR revealed that the DFDBA and DBBM groups showed a higher mRNA level of MMP12, Bcl2A1, S100A4, and Postn compared with the control (P < .05). Histology showed that, compared with the control, the volume of new bone was higher in both types of bone grafts. Immunohistochemistry using an MMP12 antibody confirmed the microarray results because the MMP12 immunoreactivity intensified, and a positive expression of MMP12 increased significantly in the DFDBA and DBBM groups. Conclusion: Both DFDBA and DBBM had a gene expression network involved in new bone formation, which coincided with an increased expression of MMP-12 and osteoclast activity. Both types of graft materials appeared to connect with genes that stimulate bone remodeling at 3 months of bone grafting. Keywords: bone graft, DBBM, DFDBA, microarray, real-time PCR

Purpose: To evaluate the influence of low-dose protocols, with different numbers of basis images, on the precision of linear bone measurements in CBCT images. Materials and methods: Five polyurethane mandibles, with different levels of bone resorption, were used in this in vitro study. To obtain the reference standard, landmarks were made in the mandibular superior and buccal cortices, and then a digital caliper was used to measure the bone height and thickness at these regions. CBCT images were obtained with the PaX-i3D (Vatech) unit set at 50 kV, 4 mA, 0.2-mm voxel size and 50 × 50-mm field of view. Keeping these parameters fixed, each mandible was scanned twice, with different protocols: Low dose (L) had an acquisition time of 24 seconds and 720 basis images, and ultralow dose (UL) had an acquisition time of 15 seconds and 450 basis images. Then, measurements of bone height and thickness were performed on the images, using the previously determined landmarks as reference. The obtained data were submitted to statistical analysis, with a significance level of .05. Analysis of variance, Student t test, and intraclass correlation coefficient were employed. Results: Regarding bone height, there were no significant differences between the measurements obtained with the L and UL protocols (P = .8648). Additionally, the L and UL protocols did not differ in relation to the reference standard (P = .8717 and P = .9928, respectively). Likewise, there were no significant differences between the measurements obtained with the L and UL protocols (P = .7969) for bone thickness, nor between these protocols and the gold standard (P = .7455). Conclusion: Considering the great demand for precise measurements in implantology, protocols of low-dose radiation can be used without compromising clinical planning. Keywords: cone beam computed tomography, dental implants, radiation dosage

Purpose: To evaluate survival, complication rates, and bending moments of one- and two-piece zirconia implants restored with different abutment materials and lithium disilicate crowns after aging, compared to titanium implants restored with titanium base-supported lithium disilicate crowns. Materials and methods: Sixty anterior crowns were either screwretained on two-piece titanium implants (C) and two-piece zirconia implants (T1, T2, T3) or cemented on one-piece zirconia implants (T4), resulting in 5 groups with 12 specimens each. For the screw-retained crowns, different abutment materials and implant connections were tested: titanium base with internal conical connection and horizontal joint component (C and T2), zirconia with internal hexagonal connection and horizontal joint component (T1), and polyetherketoneketone with internal hexagonal connection and horizontal joint component (T3). After artificial aging with thermocycling (5°C to 50°C) and chewing simulation (1,200,000 cycles, 49 N, 1.67 Hz), the surviving specimens were loaded until fracture, and the bending moments were calculated. Survival rates and respective differences during aging were analyzed with the Kaplan-Meier log-rank test, while complication rates were compared with chi-square tests. Bending moment data were evaluated using the Kruskal-Wallis test (α = .05). Results: Survival rates after artificial aging ranged from 75% (T1) to 100% (C and T4) without significant differences between the groups (P > .05). Only 41.5% of the surviving specimens were free of complications, while the remaining presented screw-loosening, loss of retention of crowns, or cracks on the crown or implant level. The complication rates varied significantly among the groups (P < .05). The mean bending moments were 173.7 × 20.1 (C), 114.5 × 20.1 (T1), 171.1 × 46.1 (T2), 258.1 × 147.4 (T3), and 194.7 × 30.9 Ncm (T4), and group T1 exhibited significantly lower median bending moment values than the other groups (P < .001). Conclusion: The zirconia one- and two-piece implants presented high survival rates after aging, yet the number of technical complications was high. New prosthetic solutions, such as titanium bases or polyetherketoneketone abutments, may offer a comparable treatment option to restore two-piece zirconia implants. Keywords: ceramic implants, implant abutment, polyetherketoneketone, titanium, two-piece implants, zirconia

Purpose: Short implants are used in clinical conditions of insufficient vertical bone availability. This study aimed to compare the primary stability of short implants with different macrodesigns placed in different bone densities in vitro. Materials and methods: One hundred twenty short (6-mm) implants (20/group) were placed at the bone level in commercially available polyurethane blocks representing type I and IV bone quality. The groups were as follows: test A group (4.6-mm diameter with tapered body), test B group (4.8-mm diameter/cylindric microthreaded neck), and test C group (4.8-mm diameter, cylindric body with polished collar, three threads at the intraosseous portion). Implant primary stability was assessed using insertion torque and implant stability quotient (ISQ) values. A blinded calibrated clinician recorded all measurements. Statistical comparisons were completed using a one-way analysis of variance (ANOVA) and Bonferroni posttests. Results: The insertion torque values (mean ± SD) for groups A, B, and C in type I bone were 52.50 ± 5.25, 49.00 ± 5.98, and 46.25 ± 3.93, and in type IV bone, the values were 14.00 ± 2.05, 15.50 ± 2.76, and 9.75 ± 1.11, respectively. Also, the ISQ values were 67.25 ± 2.760, 69.25 ± 1.67, and 61.80 ± 5.68 (type I bone); and 53.27 ± 1.99, 60.65 ± 2.11, and 51.97 ± 4.51 (type IV bone), respectively. The comparison showed statistical differences in ISQ (Bonferroni adjusted P < .0001) for the A and B groups but also for the A and C groups (type I bone), in soft bone between the A and B groups and between the B and C groups, and also for the insertion torque values for the A and C groups and between the B and C groups in type IV bone. Conclusion: Short implant macrogeometry defines primary stability. Short implants with 6-mm length and multiple threads can achieve good primary stability in vitro in type I and IV artificial bone. Keywords: implant design, primary stability, short implants

Purpose: To compare the temperature changes during the setting process of two provisional crown materials, polymethyl methacrylate (PMMA)-based acrylic resin (Ac) and bis-acryl composite resin (Co), at the first thread surface of one-piece implants. Materials and methods: Twenty-two 3.3-mm-diameter one-piece implants were divided into two groups according to the provisional restoration material. Implants were mounted on a Plexiglas apparatus. A K-type thermocouple was fixed at the most coronal thread. Baseline (Bl Temp) and maximal (Max Temp) temperatures of both groups were recorded during the curing process. Total heat flux (THF) at the implant surface and thermal amplitude (Temp-Amp) were calculated. Differences between groups were compared using a t test for unpaired observations. Results: Upon curing, a statistically significant increase in the Max Temp from the Bl Temp was detected in both groups, with a greater increase in the Ac compared with the Co group. The Temp-Amp and the THF were two times greater in the Ac group than the Co group. Conclusion: Significant heat is produced during the polymerization of PMMA-based resin and bis-acryl composite resin provisional crowns in one-piece implants. To decrease the risk of thermal challenge at the implant cervical aspect associated with restoration of immediately loaded implants, bis-acryl composite resin should be used. Keywords: acrylic, composite, resin, immediate restoration, implant, temperature

Purpose: This study aimed to assess the fracture resistance of zirconia (Zr), reinforced polyetheretherketone (PEEK), and polyetherketoneketone (PEKK) implant abutments restored with glass-ceramic crowns after thermomechanical aging. Materials and methods: Zr, reinforced PEEK, and PEKK titanium base abutments were divided into three groups (n = 10). CAD/CAM maxillary central incisor crowns were fabricated using monolithic lithium disilicate and luted to the abutments using resin cement. The specimens were thermomechanically aged (1.2 × 10⁶ cycles, 49 N, 5°C to 55°C). After testing fracture strength and determining fracture patterns, statistical analyses were made using the one-way analysis of variance (ANOVA) and Tukey post hoc tests (α = .05). Results: Fracture resistance of the PEKK abutments (541.90 ± 68.49 N) was significantly lower than the Zr (780.65 ± 105.77 N) and reinforced PEEK (741.09 ± 99.84 N) abutments (P = .000). A significant discrepancy was not detected between the reinforced PEEK and Zr abutments. Failures usually formed due to crown or abutment fracture, plastic deformation of the titanium base or screw fracture in the Zr group, crown fracture or separation of the abutment-crown complex from the titanium base in the reinforced PEEK group, and abutment fracture without crown deformation in the PEKK group. Conclusion: After thermomechanical aging, the reinforced PEEK abutments exhibited similar fracture resistance to the Zr abutments. All abutment types withstood the physiologic occlusal forces typical for the oral anterior region. Before considering them as alternative esthetic implant abutment materials, further in vitro and clinical studies are needed to determine their long-term performance. Keywords: CAD/CAM, esthetics, implant abutments, polyetheretherketone, polyetherketoneketone, zirconia

Purpose: To evaluate and compare human chorionic amniotic membrane and platelet-rich fibrin on new bone formation and soft tissue healing in extraction sockets indicated for rehabilitation with dental implants. Materials and methods: A prospective, triple blind clinical study was conducted. The inclusion criteria were as follows: patient with two extraction sites each in the same arch, intact buccal bone and soft tissue around the socket, and recommended rehabilitation with dental implants. Postextraction, the sockets were randomly placed with human chorionic amniotic membrane in one site and platelet-rich fibrin in the other site. After 3 months, a trephine drill was used to take a biopsy of the respective sites for soft and hard tissue samples. The outcome parameters that were assessed histologically were percentage of new bone formation and lymphocyte density. Results: After screening 80 patients, eight participants were recruited for the study. The mean percentage of new bone formation in the human chorionic amniotic membrane group was 45.71% ± 4.82%, and for the plasma-rich fibrin group, it was 41.39% ± 6.29%, showing no statistically significant difference (z = 0.99, P = .31). In the human chorionic amniotic membrane group, six out of eight sites had mild lymphocyte density, while the plasmarich fibrin group had equal numbers of mild and moderate lymphocyte density. No statistically significant difference between the groups (Fischer test value = 0.60, P = .25) was noted. Conclusion: Within the limitations of the study, the results showed that there is no difference in the efficiency of human chorionic amniotic membrane compared with platelet-rich fibrin in achieving new bone formation and soft tissue healing in the extraction socket. Keywords: dental implants, extraction sockets, human chorionic amniotic membrane, platelet-rich fibrin

Purpose: This study aimed to examine clinical and patient-centered outcomes of resilient stud and stress-free bar attachments used for immediately loaded implants supporting mandibular overdentures. Materials and methods: Thirty edentulous patients with sufficient bone mesial and distal to the mental foramen received new dentures. The patients were randomly assigned into two groups. After 3 months of adaptation, four implants were placed in the canine and second premolar areas of the mandible using computer-guided surgery and the flapless surgical approach. Overdentures were connected immediately to the implants using either resilient stud (Locator) or stress-free implant bar (SFI-Bar) attachments. Marginal resorption of bone, plaque and gingival indices, pocket depth, and implant stability were evaluated for both groups at baseline (prosthesis delivery) and 6 and 12 months thereafter. Implant survival and patient satisfaction were calculated after 12 months. Results: For both groups, marginal bone loss (P < .043), plaque scores (P < .001), and probing depth (P < .002) increased significantly with time. SFI-Bar recorded lower marginal bone loss (P = .048) and higher plaque scores (P = .021) and probing depth (P = .001) than Locator after 12 months of denture insertion. The implant survival was 96.6% and 98.3% for Locator and SFI-Bar, respectively. No significant difference was found in the survival rate between groups (P = .56). Locator showed significantly higher general satisfaction, satisfaction with retention, comfort, and cleaning of overdentures compared with SFI-Bar (P < .001). Conclusion: Within the limits of this investigation, both resilient stud and stress-free bar attachments can be used successfully with mandibular four-implant overdentures subjected to an immediate loading protocol. However, studs may be preferred regarding peri-implant soft tissue health, patient satisfaction with retention, cleaning, and comfort, and stress-free bar attachments could be more effective in terms of marginal bone preservation. Keywords: attachment, bar, immediate loading, implant, Locator, overdentures, SFI

Purpose: The objective of this study was to report implant survival rates, marginal bone loss, and the impact of prosthesis type among patients with type 2 diabetes mellitus (DMT2), with high hemoglobin A1C (HbA1c) values. Materials and methods: This retrospective study utilized patient medical records from an oral surgeon's office. Patients who had moderately or poorly controlled DMT2 with HbA1c values up to 10% were reviewed. Inclusion criteria were partially or fully edentulous patients diagnosed with DMT2 who were subsequently treated with implant-supported prosthetic restorations. Patients were at least 18 years of age. Exclusion criteria were patients who did not present for annual follow-up visits, patient records with incomplete surgical or restorative data, or nondiagnostic radiographs. All the fixed restorations were cement-retained, and the removable restorations were supported by two to six implants. Marginal bone loss and the consequences of prosthetic type were assessed from the last available radiograph compared with the one taken after the surgical procedure. Results: Data of 357 implants were extracted from the records of 38 patients with HbA1c values (6.9% to 10.0%). The mean follow-up was 7.3 years, with a minimum of 5 years. Six implants failed, yielding a 98.4% overall implant survival rate. The patients were divided into two groups according to the HbA1c values before implant placement. The moderately controlled group included 25 patients with DMT2, with HbA1c values of 6.9% to 8.0%, and the poorly controlled group included 13 patients, with HbA1c values of 8.1% to 10.0%. The overall mean bone loss was 2.02 ± 2.43 mm. In both groups, the maxilla demonstrated more bone loss than the mandible (P < .05). Marginal bone loss in moderately controlled and poorly controlled groups was 1.86 (± 2.21) mm and 2.33 (± 2.85) mm, respectively (P < .05). Removable prostheses also revealed greater bone loss rates compared with fixed prostheses in both groups (P < .05). Conclusion: Patients with high HbA1c values (8.1% to 10.0%) had more marginal bone loss than those with lower HbA1c values. Removable dentures should be reconsidered as a standard treatment option in these patients. Keywords: bone loss, diabetes mellitus type 2, removable denture

Purpose: There is little knowledge about healing patterns for the socket with an intentionally retained root fragment: a socket shield. The clinical observation is soft tissue ingrowth next to the socket shield. The aim of this study was to evaluate the effectiveness of autologous grafting matrices in preventing soft tissue ingrowth. Materials and methods: Patient data from a private clinic were searched for sockets with a socket shield left to heal with blood clot or grafted with autologous materials: autologous platelet-rich fibrin (PRF), scraped particulate bone, cortical tuberosity bone plate, or particulate dentin and covered with PRF membranes. The included sites were exposed by the flap 4 months after the first surgery, and soft tissue ingrowth depth and width next to the root fragment were measured by a scaled probe and documented. Results: Evaluation of 34 sites showed the greatest depth of soft tissue ingrowth in the nongrafted sockets (6.0 ± 0.0 mm). Grafting with PRF plugs (depth of 2.3 ± 0.2 mm) or particulate bone (depth of 2.7 ± 0.6 mm) decreased soft tissue ingrowth. Grafting with particulate dentin or cortical tuberosity bone plate resulted in a soft tissue ingrowth depth of only 1 mm, yielding the best clinical outcome. Radiography confirmed those findings. Conclusion: Autologous dentin particulate or tuberosity cortical bone plate is most effective for preventing soft tissue ingrowth. Keywords: bone graft, case report/series, dentin graft, platelet-rich plasma, socket shield, soft tissue ingrowth

Purpose: The aim of this study was to evaluate the survival and success rates of oral rehabilitations in a shortened maxillary dental arch and expanded maxillary sinus with 4-mm extrashort implants splinted to longer ones. Materials and methods: One 10-mm and one/two extrashort 4-mm titanium-zirconium SLActive tissue-level dental implants were inserted into 11 patients with limited vertical bone availability due to an expanded maxillary sinus antrum. Immediately and 6 months after insertion, implant stability resonance frequency analysis (RFA) values were assessed with an Osstell device. Splinted crowns combining 4- and 10-mm implants were supplied to all 11 cases. Results: In 10 cases, the bone quality was type III, and in one case, type IV. Among 17 4-mm and 11 10-mm implants, the median RFA values were 61 (interquartile ranges [IQR]: 59 to 64) and 66 (IQR: 64 to 72). One 4-mm implant failed to osseointegrate and was removed. After 6 months of healing, secondary-stability measurements of 16 of the remaining 4-mm implants increased to 68 (IQR: 62 to 72) and of 10-mm implants to 78 (IQR: 77 to 80). After 1 year, all (11/11) oral rehabilitations supported by 10-mm (11/11) and 4-mm (16/16) implants were functional. The medians and IQRs of the probing depths (median: 2.8 mm, IQR: 2.3 to 3.1 mm vs median: 2.9 mm, IQR: 2.4 to 3.1 mm) and the crestal bone loss (median: 0.75 mm, IQR: 0 to 0.9 mm vs median: 0.22 mm, IQR: 0 to 0.4 mm) for the 10-mm and 4-mm implants, respectively, were similar. Conclusion: Rehabilitations with splinted crowns combining 4- and 10-mm implants demonstrated a favorable 1-year performance in a shortened maxillary dental arch. Keywords: 4-mm extrashort implants, case-report/series, crestal bone loss, maxillary sinus, posterior maxilla, survival rate

Purpose: The aim of this study was to clinically and radiographically evaluate mandibular overdentures supported by four short implants combined with two different doses of photobiomodulation (PBM). Materials and methods: A split-mouth design was applied; six completely edentulous male subjects received four short implants in the canine and second premolar area. Short implants were inserted via a digital fully guided approach with a stereolithographic surgical guide. All patients received five PBM sessions immediately after surgery and every 48 hours. Group A (n = 6) implants on the right side received a dose of 3.75 J/cm², and group B (n = 6) implants on the left side received a dose of 7.5 J/cm². Evaluation of peri-implant probing depth (PIPD), modified Gingival Index (MGI), and vertical bone loss was performed at the time of prosthetic loading and 6 and 12 months later. The implant stability quotient (ISQ) was also assessed 6 and 12 months after loading. Results: There was no significant difference between both groups regarding PIPD values. However, a minor but significant increase from the baseline (P < .001) was observed in PIPD values in both groups after 12 months. The MGI scores at the different time intervals were very low for both groups. The mean vertical bone loss after 12 months was minimal for both groups but statistically significant from the baseline (P < .001). ISQ values for both groups after 12 months revealed a significant increase from the baseline, and group B values were significantly higher than those of group A. Conclusion: Within the limitations of this study, a mandibular overdenture supported by four short implants is a valid treatment modality for atrophic mandibles, and a PBM dose of 7.5 J/cm² has a potential positive influence on implant healing and osseointegration. Keywords: atrophic mandible, guided implant surgery, photobiomodulation, short dental implant

Purpose: The objective of this study was to quantify the probability of implant failure over time from intrinsic patient factors using a population of patients from multiple private practices. Materials and methods: The records for this retrospective, multicenter cohort study were randomly selected from eight private practices. The primary outcome variable was time to event (implant failure or last known follow-up). The included independent variables were age, sex, diabetes status, smoking status, and arch location. Analyses were performed with Cox proportional hazards on three models: univariate, full multivariate, and systemic factor multivariate. The probability of implant survival at 1, 5, and 10 years was calculated using univariate time-to-event modeling on log-normal distribution with 95% CIs and Cox proportional hazard tests for significance. The Kaplan-Meier survival curve was calculated for patients < 71 years of age. Results: Eight hundred thirty-five implant-level records from 378 patients were collected for analyses. The mean patient age was 60 years, and 48% were men, 15% reported a history of smoking, and 16% reported having diabetes. The follow-up time was as long as 17 years, with a mean of 23.1 months, and a median of 7 months. The hazard ratio (HR) for implant failure due to sex (HR = 1.18; 95% CI: 0.52 to 2.66), smoking (HR = 1.30; 95% CI: 0.49 to 3.46), diabetes (HR = 1.17; 95% CI: 0.35 to 3.86), and arch location (HR = 2.13 to 3.39) failed to reach the threshold within any Cox proportional hazards model (P > .05). Conclusion: The implant survival probability for patients ≤ 70 years of age is 86.4% at 10 years in the course of routine private practice by experienced providers. Cautious interpretation of these results is critical, as the effects of known systemic risk factors are likely tempered by effective modifications in clinical decisions and protocols with short- and long-term follow-up maintenance. Keywords: dentistry, implants, risk, survival

Purpose: This numerical study examined the efficacy and challenges of using resonance frequency analysis to identify the stability of implants placed in mandibles. The study also examined the feasibility of using angular stiffness as an alternative index to quantify dental implant stability in mandibles. Materials and methods: A finite element model consisting of a mandible, an implant, an abutment, and a bonding layer (between the implant and the mandible) was created in commercially available software ANSYS. The level of osseointegration was modeled by varying the stiffness of the bonding layer. Three sets of boundary conditions were imposed on the mandible: fixed, rotationally free, and rotationally restrained. Three implant locations were studied: central, premolar, and molar positions. An alternative abutment mimicking SmartPeg and eight different implant lengths were also included. A modal analysis and a static analysis were conducted to calculate resonance frequencies and angular stiffness, respectively. Results: Two types of vibration modes were found. One was jawbone modes, for which the mandible deformed significantly but not the bonding layer. Resonance frequencies of the jawbone modes were not sensitive to the level of osseointegration. The other was implant modes, for which the bonding layer deformed significantly but not the mandible. Among multiple implant modes obtained, only one was trackable as the level of osseointegration increased. The resonance frequency of the trackable implant mode was very sensitive to the implant location as well as boundary conditions, but not as much to the level of osseointegration. In contrast, angular stiffness was sensitive to the level of osseointegration but not as much to boundary conditions. Conclusion: The efficacy of using resonance frequency analysis to quantify the stability of a dental implant is questionable. Its high sensitivity to implant locations and boundary conditions as well as its low sensitivity to the level of osseointegration cause huge uncertainties in correlating measured resonance frequencies to implant stability. Angular stiffness is a much more reliable indicator because of its high sensitivity to the level of osseointegration and low sensitivity to boundary conditions. Keywords: angular stiffness, dental implant, finite element analysis, resonance frequency analysis, stability

Purpose: To compare the onset of peri-implantitis, incidence of failure, and peri-implant marginal bone level changes between implants with a roughened surface and those with a machined/turned surface. Materials and methods: All patients needing two dental implants of the same size on the left and right sides of the same arch, and not scheduled for immediate loading, were enrolled between October 2012 and February 2016. The patients were randomly allocated either to Nobel Biocare MKIII or Sweden & Martina Outlink2. Rough-surface implants and machined-surface implants were used from each company. After the preparation of two identical implant sites, each implant (rough or machined of the same group) was randomly allocated to the right and left sides of the same patient, following a split-mouth design. Outcome measures were peri-implantitis onset, incidence of failure, and peri-implant marginal bone level changes. Patients were followed up for 3 years after loading. Results: One hundred fourteen patients were enrolled and treated; nine patients dropped out. Following an intent-to-treat analysis to avoid overestimation, proportions are given related to the initial number of 114 patients. Peri-implantitis incidence was 4.39% for machined implants (5/114), 0.88% for rough implants (1/114), 1.75% in the Nobel Biocare group (2 cases), and 3.51% in the Sweden & Martina group (4 cases). The failure rate was 1.75% in machined implants (2/114), 0.88% in rough implants (1/114), 0.98% in the Nobel Biocare group (1/114), and 1.85% in the Sweden & Martina group (1/114). No statistically significant differences in marginal bone loss were found comparing different surfaces, while marginal bone loss was significantly lower in Nobel Biocare than in Sweden & Martina implants. Conclusion: Based on the results of this study, no significant differences can be demonstrated in either peri-implantitis or failure rate or in marginal bone loss between rough and machined implants. Marginal bone loss was significantly worse in machined-surface Sweden & Martina than in rough-surface Nobel Biocare implants. Keywords: implant failure, implant surface, machined implant surface, peri-implantitis, rough implant surface