The International Journal of Oral & Maxillofacial Implants, 05/2022

Purpose: To investigate the impact of implantoplasty (IP) with or without regenerative procedures on treatment outcomes of peri-implantitis. Materials and Methods: Electronic and manual literature searches were conducted for clinical trials published up to October 2020 that evaluated clinical outcomes (at least 6-month follow-up) after peri-implantitis treatment involving IP. The implant survival rate and clinical parameters (eg, probing depth [PD], bleeding on probing [BOP], marginal bone loss [MBL], clinical attachment level [CAL], and mucosal recession [REC]) at baseline and follow-ups were extracted from original articles for qualitative analyses. Risk ratio and weighted mean difference with 95% CI were calculated using a random-effects model. Results: Out of 322 studies, 17 (9 randomized controlled trials, 4 controlled clinical trials, and 4 case series) were included in the present study. The regeneration group presented a 97% (95% CI: 0.95 to 1.00) implant survival rate, and the nonregeneration group showed a 94% (95% CI: 0.90 to 0.98) survival rate. Both groups revealed similar outcomes in PD and BOP reductions and soft tissue REC. However, the regeneration group had more favorable results in MBL. Conclusion: Data from this study suggested that applying implantoplasty during a regeneration or nonregeneration surgical approach resulted in a high implant survival rate and peri-implantitis resolution. Although no differences were found in the majority of clinical parameters in both groups, the regenerative approach resulted in more radiographic bone fill than the nonregenerative treatment. Keywords: implantoplasty, peri-implantitis, regeneration, surgical treatment, systematic review

Purpose: To assess the effect of nongrafted and grafted materials on transalveolar sinus floor elevation (TSFE) with implant placement. Materials and Methods: Relevant studies published between January 1, 1994, and July 31, 2021, were selected by searching Embase, PubMed/MEDLINE, Web of Science, and Cochrane Central Register of Controlled Trials. The study subjects were restricted to humans, and the language was limited to English. The study was confined to randomized controlled trials, controlled clinical trials, and observational studies (prospective and retrospective cohort) related to TSFE with and without bone-grafting materials. Two reviewers independently extracted study data and conducted quality assessments according to the Cochrane handbook and NOS scale. RevMan 5.3 and Stata 15.1 software were then used to analyze the research data that met the inclusion criteria. Results: A total of nine articles were included, including 421 implants in the graft group and 502 implants in the nongraft group. Meta-analysis showed that there was no significant difference in the implant failure rate (RR = 1.03, 95% CI: 1.00, 1.06, P = .08) or marginal bone loss (SMD = 0.06, 95% CI: –0.23, –0.35, P = .69) between implants with and without graft materials after TSFE. The amount of endosinus bone gain in the nongraft group was significantly lower than that in the graft group (SMD = –1.07, 95% CI: –1.73: –0.41, P = .0001). Conclusion: TSFE in implants with or without grafting can achieve similar results, but there may be more bone gain in TSFE with grafting. Keywords: bone graft material, guided bone regeneration, maxillary sinus, maxillary sinus elevation, meta-analysis, oral implants, survival rate, transalveolar sinus floor elevation

Purpose: To observe the effect of different prosthetic materials (polymethyl methacrylate [PMMA] and flowable composite [FC]) on marginal bone loss, pink esthetic score (PES), and cytokine levels (receptor activator of nuclear factor kappa-Β ligand [RANKL] and osteoprotegerin [OPG]). Materials and Methods: A total of 46 patients (31 women, 15 men) were treated with immediate implant therapy after tooth extraction. For standardization, only the maxillary premolar tooth of each patient was restored, and also, both of the adjacent teeth were present in the dental arch. Provisional crowns were prepared before the surgery on patient models with two different materials (24 PMMA, 22 FC). Following the surgical procedure, provisional crowns were adjusted on polyetheretherketone (PEEK) abutments as nonfunctional in centric and eccentric movements. After the surgery, patients were evaluated monthly for 3 months. At each follow-up, periapical radiography was obtained by the parallel technique, and peri-implant crevicular fluid (PICF) was collected. Pink esthetic scoring was done. MBL was calculated for the mesial and distal sides separately. Cytokine levels were analyzed from PICF. Statistical analyses (Shapiro-Wilk, Mann-Whitney U, independent-samples t test, Wilcoxon t test, paired-samples t test, and Friedman two-way analysis of variance with Bonferroni correction) were completed (α = .05). Results: PES was increased significantly within groups (P < .01). However, there was no statistically significant difference between groups. According to the Mann-Whitney U test, no significant difference was found for the MBL (P > .05). When the RANKL/ OPG values were evaluated within the group by using the Friedmann two-way analysis of variance test, no significant difference was found (P > .05). Conclusion: Similar pink esthetics, cytokine levels, and bone loss can be achieved using a protocol including immediate implants, particle grafts, soft tissue graft, PEEK abutments, and provisional restorations fabricated using PMMA and FC. Keywords: immediate placement, implant-supported fixed provisional crown, OPG, RANKL

Purpose: To evaluate the role of different healing abutment designs in compensating for the buccolingual volumetric tissue change that occurs following flapless single-tooth immediate extraction placement in the molar area. Materials and Methods: Patients in need of extraction and replacement of a first or second molar in the mandible or maxilla were consecutively recruited. Immediately after extraction and implant placement, an abutment was connected. Five different types of abutments were randomly selected to be used for each case. The study population was divided into five categories according to abutment design: 5-mm diameter healing abutment (group 1); 6-mm diameter healing abutment (group 2); 7.5-mm diameter healing abutment (group 3); provisional restoration (group 4); and customized healing abutment (group 5). The buccopalatal dimension (BPD) was measured on the study casts at 1, 3, and 5 mm apical to the free gingival margin, and horizontal volumetric changes were compared between baseline and 2, 4, and 6 months. Results: A total of 267 implants were inserted in 246 patients. The breakdown of placed implants for each group was as follows: 67 implants in group 1; 64 in group 2; 71 in group 3; 33 in group 4; and 32 in group 5. Changes in the mean horizontal ridge dimension were as follows. After 6 months in group 1, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 4.21 ± 0.158, 3.38 ± 0. 178 and 2.35 ± 0.178 mm. In group 2, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 3.16 ± 0.198, 2.56 ± 0.198, and 1.62 ± 0.198 mm. In group 3, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 2.53 ± 0.138, 2.16 ± 0.144, and 1.56 ± 0.144 mm. In group 4, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 1.11 ± 0.179, 1.23 ± 0.179, and 1.12 ± 0.179 mm. In group 5, BPD diminished at 1-, 3-, and 5-mm distance from the free gingival margin, respectively, by 0.25 ± 0.225, 0.30 ± 0.225, and 0.19 ± 0.225 mm. Mixed-effect regression and post hoc means comparisons were used to model the impact of the restoration technique, height of measurement, and time on BPD using a significance reference level of .05. Statistical analysis showed that the type of abutment, the height of measurement, and the time significantly influenced the BPD and that there were complex interaction effects between these variables. Conclusion: The observed volumetric soft tissue changes in the 6-month short-term follow-up appeared to vary based on the use of different healing abutment sizes that were connected to implants placed immediately after tooth extraction in the molar area. In particular, the use of a customized healing abutment resulted in preservation of the original horizontal dimension of the molar soft tissue. Keywords: dimensional changes, flapless surgery, healing abutment, immediate placement, molar site, provisional restoration

Purpose: To identify the impact of residual bone height on 5-year implant survival and prosthetic complication rates in patients who underwent maxillary sinus grafting. Materials and Methods: A total of 87 consecutive patients were treated with 104 lateral approach maxillary sinus floor augmentation procedures with 100% deproteinized bovine bone and received 169 implants. The analysis considered patient age, sex, time of implant placement, and residual bone height. Patients with < 3 mm residual bone height were assigned to the study group; otherwise, they were placed in the control group. Results: The mean follow-up was 68.2 months (0 to 103 months). The mean residual bone height was 1.8 mm in the study group and 4.1 mm in the control group. The 5-year implant survival and prosthetic complication rates were, respectively, 97.4% and 8.0% in the study group and 100% and 12.5% in the control group. Residual bone height, sex, age, and time of implant placement were not significant factors for the 5-year implant survival or prosthetic complication rate. The lateral bone wall was significantly thinner in the study group. The grafted bone height reduction was significantly different at 6 months and 2 years postoperation in both groups, but there was no difference in the change in grafted bone height reduction over time between the two groups. Conclusion: A residual bone height < 3 mm did not impact the survival rates of implants placed in grafted maxillary sinuses or the prosthetic complication rate after 5 years of functional loading. Keywords: atrophic maxilla, longitudinal studies, residual bone height, sinus floor augmentation, survival

Purpose: To investigate the effects of periopathogens on bone grafts for maxillary sinus floor augmentation and implant survival. Materials and Methods: A cohort study was designed. Samples from maxillary sinus floor augmentation sites and from periodontal pockets in adjacent teeth of the same patients were collected during the surgery and following periodontal maintenance and plaque removal. Polymerase chain reaction (PCR) was performed by an external lab service for analysis of the following periopathogens: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, and Treponema denticola. Correlations between the presence of periopathogens in sinus sites and periodontal pockets in adjacent teeth and the clinical findings (bone and implant survival) were studied. Results: A total of 23 patients were suitable for study inclusion. Periopathogens were found in sinus sites in 6 patients (26%) and in tooth sites in 15 patients (65%). There was low correlation for the presence of periopathogens between tooth sites and sinus sites and for complications. Conclusion: The presence of periopathogens as revealed by PCR was lower in sinus sites compared with tooth sites. Their presence neither caused bone pathology nor affected dental implant survival. The presence of periopathogens in sinus sites is inevitable even under periodontal maintenance. Although its presence did not endanger implant survival, future studies are recommended for studying this issue. Further analyses of the presence of periopathogens in cases of bone resorption at the apex of dental implants inserted into sites of augmented sinuses are warranted. Keywords: Actinobacillus actinomycetemcomitans, bacteria, bacteroides gingivalis, Prevotella intermedia, sinus augmentation sites, Tannerella forsythia, Treponema denticola

Purpose: To examine the short-term outcomes of maxillary sinus augmentations consisting of laterally and apically displacing the palatal wall through a transcrestal approach. Materials and Methods: The maxillary sinus floor was fractured in its palatal aspect by allowing a displacement in the buccal and apical direction with a magnetoelectric system. A medial displacement of the alveolar crest in its palatal bony plate was performed at the same time. Crestal bone change was investigated using superimposed preoperative and postsurgical computed tomography scans. Clinical and radiologic outcomes over 1 year were evaluated. Results: A total of 18 implants were selected for retrospective volumetric and linear analyses. Sinus floor and alveolar bone augmentation surgery led to a significant increase in the bone volume (P = .0002) from 0.134 ± 0.060 cm3 to 0.639 ± 0.166 cm3, with an overall gain of +0.504 ± 0.139 cm3. No part of the implant apices appeared to protrude into the maxillary sinus at the 1-year follow-up. The width of the alveolar crest changed from 5.1 ± 0.5 mm to 6.5 ± 0.7 mm, with a significant increase of +1.4 ± 0.6 mm registered at 1 year. However, a marginal bone loss of 1.0 ± 0.8 mm was observed. When tooth positions were investigated, no significant differences between the two groups (premolars versus molars) were found. Conclusion: Significant and effective bone gains allowed proper placement of the dental implants but with a minimal loss of peri-implant bone volume. Keywords: bone displacement, computerized tomography image, dental implants, infracture technique, maxillary sinus

Purpose: To qualitatively and quantitatively evaluate histologic osseointegration parameters of implants designed with decompressing vertical chambers between the threads with two different surface treatments (TiO₂ blasting + maleic acid vs TiO₂ blasting + maleic + HCl) in a large translational animal model at 3 and 6 weeks in vivo. Materials and methods: Nine female sheep were used, and 72 implants with trapezoidal threads and decompressing vertical chambers of 0.6 mm in diameter and 0.2 mm in depth were placed in the ilium crest. After 3 and 6 weeks, the animals were euthanized, and biomechanical and histomophometric analyses were performed. Results: Survey histologic evaluation indicated intimate contact between the bone and the implants independent of surface treatment at both times in vivo. Bone formation at both time points depicted an intramembranous-type healing pattern between the implant threads. The mean removal torque values for all groups showed a relative increase in removal torque from 3 to 6 weeks. In terms of bone area fraction occupancy analysis, significant differences were found at 6 weeks between surface treatments (P = .046), where the experimental surface yielded higher degrees of bone area fraction occupancy. Conclusion: Conical implants with decompressing vertical chambers between threads presented similar osseointegration parameters regarding bone-toimplant contact and torque-out test values irrespective of surface treatment. However, shifting from a minimally rough to a moderately rough surface (experimental surface with supplemental acid-etching) resulted in significantly improved bone area fraction occupancy at 6 weeks. Keywords: dental implants, macrodesign, osseointegration, surface treatment

Purpose: To study the distribution of markers of mesenchymal stem cells (clusters of differentiation-29 and -44), osteoblasts (osteocalcin), and transforming growth factor-β1 in the mandibular tissue of miniature pigs after on-bone fixation of a free gingival graft. Materials and Methods: Six outbred male miniature pigs 2 years of age were used in the study. In the external surface of the mandible, the periosteum was excised from all over the free gingival graft fixation area. A free gingival graft was placed on the wound and fixed. In control animals, instead of free gingival graft, a piece of mucoderm (porcine accellular dermal matrix, Botiss Biomaterials) was placed on the wound and fixed. Three months after the surgery, a portion of bone tissue was sampled from the free gingival graft insertion area. The samples were immunohistochemically stained using antibodies against osteoblast and mesenchymal stem cell markers. Results: Three months after surgery, high expression levels of the aforementioned markers were detected in the contact zone between the graft and alveolar bone. Clusters of differentiation-29– and -44–immunopositive cells predominated at the border of the new bone tissue and gingival lamina propria as well as in Haversian canals. Osteocalcin-positive cells were observed mainly in the layer of outer circumferential lamellae, on the surface of concentric lamellae of young osteons forming Haversian canals, and in the Haversian canals in the immediate vicinity of the graft. The bulk of transforming growth factor-β1–expressing cells occurred in the connective tissue Volkmann and Haversian canals and the adventitious and inner vascular membranes. Conclusion: On-bone free gingival graft fixation results in remodeling of the alveolar bone and is accompanied by a change in the immunoreactivity against factors controlling osteogenic differentiation. Clusters of differentiation-29 and -44 expression in mandibular bone tissues suggest that free gingival graft placement results in activation of mesenchymal stem cells and their transforming growth factor-β1–mediated differentiation into osteocalcincontaining osteoblasts. Keywords: mandible, mesenchymal stem cells, osteogenic differentiation, osteointegration

Purpose: To seek out the bone regeneration effect of human umbilical cord-mesenchymal stem cell (hUC-MSC)-derived exosomes of loaded chitosan/hydroxyapatite (CS/HA) scaffold in a rat calvarium bone regeneration model. Materials and methods: The hUC-MSC exosomes were purified and characterized. The scaffolds were prepared by a freeze-drying method. Animals were divided into five groups, and the CS/HA/exosome (CS/HA/Exo) scaffolds were transplanted to 5 × 2-mm critical-sized calvarial bone defects for repair in rats. All animals were sacrificed at the postoperative sixth week. Immunohistochemical and histologic analyses were performed. Results: Scanning electron microscopy (SEM) images showed that the exosomes were round-shaped vesicles with bounded membrane, and the diameter of the exosomes was 83.728 ± 27.269 nm. Histologic analysis showed that mean new bone volumes were statistically significantly higher in the CS/HA/Exo group (1.83 ± 0.54, P_{CS/Exo-CS/HA/Exo} = .000), and other new bone volumes in the other groups were statistically significant compared with the control (CS/Exo 1.50 ± 0.14 mm³; CS 1.20 ± 0.43 mm³; control 1.06 ± 0.10 mm³; and CS/HA 1.43 ± 0.66 mm³). Conclusion: The CS/HA/Exo combination is a novel treatment for bone defect repair to induce bone formation. The CS scaffold can significantly promote bone regeneration compared with the control. Moreover, the combination with HA and exosomes is promising for applications in bone tissue regeneration. Keywords: bone tissue engineering, chitosan, exosomes, mesenchymal stem cell

Purpose: To evaluate whether the placement of endosseous dental implants along with intentionally retained root fragments enhances peri-implant histologic characteristics and outcomes in healthy animal models. Materials and Methods: Two review authors independently performed electronic literature searches across the PubMed/MEDLINE, LILACS, EBSCOhost, and Science Direct databases by using different keywords and Medical Subject Headings terms to identify relevant articles. Only preclinical animal trials evaluating the histology of peri-implant tissues around endosseous dental implants placed along with intentionally retained root fragments were included in the review. The risk of bias assessment was investigated using the Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) tool, and the reporting quality of each trial was evaluated using the Animal Research: Reporting in Vivo Experiments guidelines. Results: Seven preclinical trials including a total of 33 animals and 155 endosseous dental implants were eligible for the analysis. One trial reported the histologic assessment of peri-implant tissues around endosseous dental implants with ankylotic root fragments, whereas the other six studies used nonankylotic root fragments. The effects of the length of retained root fragments on peri-implant tissues were reported in two trials that showed contrasting results. The effects of the width of retained root fragments were assessed in two trials reporting that a remaining thickness < 2 mm and buccal bone thickness > 3 mm favors alveolar bone preservation over a period of 12 weeks. Although the mean quality assessment score for all preclinical trials was moderately high, the summary for the risk of bias presented a high risk. Conclusion: Limited data and short-term preclinical evidence showed optimal peri-implant histologic findings of endosseous dental implants placed along with intentionally retained root fragments. However, further preclinical histologic evaluation with homogenous populations and long-term controlled clinical studies are needed to substantiate its applicability in clinical situations. Keywords: alveolar bone preservation, animal study, dental implant, histology, immediate implant, root T-belt technique, socket shield technique, SYRCLE tool, tooth retention

Purpose: To monitor the early bone reaction in a canine model to a conventional sandblasted and dual acid-etched implant surface (ABT), a nanostructured hydrophilic surface (Nano), a dry salt–bioactivated ultra-hydrophilic surface (Hydro), and a bioactivated nanosurface obtained from the addition of dry salts to the Nano surface (Nano-Active). Materials and Methods: ABT, Nano, Hydro, and Nano-Active implants were placed in 12 dogs. A randomized split-mouth design was adopted. One implant of each type was placed in the mandible 3 months after tooth extraction in healed sites at the first molar region bilaterally. In the same session, the third and fourth premolars were extracted bilaterally and one implant of each type was immediately placed into the extraction socket. The dogs were euthanized at 14 and 28 days following surgery, and the peri-implant bone reaction was assessed histologically using Stevenel’s blue and alizarin red in nondecalcified sections. Results: The postoperative healing was uneventful. The 14-day histologic analysis reported nonsignificant results in terms of difference between the groups, while significant results were found 28 days after surgery. In fact, a significantly higher rate of new bone around the implant was reported in the Nano-Active compared to the Nano groups (51.0% ± 10.2% vs 36.0% ± 10.2%) and Hydro compared to the Nano groups (47.3% ± 10.7% vs 36.0% ± 10.2%). Conclusion: The results obtained indicate that new bone formed after 4 weeks demonstrated a tendency for dry salt– treated bioactivated surfaces to improve bone deposition in the interface in the early stages of healing; however, due to the limited number of dogs, the results failed to show a statistical significance. A study with a significantly larger group of animals should be performed in order to challenge the assumption that ultra-hydrophilic–surface implants might show higher bone-implant contact in immediate postextraction replacement. Keywords: bioactivated implant surface, histology, histomorphometric, nanosurface, salt-bioactivated surface, surface

Purpose: This research aimed to evaluate the stress and fatigue generated in short implants compared to regular implants in rehabilitation with fixed full-arch implant-supported prostheses in atrophic mandibles using the finite element method (FEM). Materials and Methods: Four models were constructed with different implants lengths: 4, 6, 8, and 10 mm. A 100-N oblique load was applied to evaluate the stress on the bone, implant, and prosthetic components. Results: Similar behavior was observed for all groups, except for 4 mm, which showed more discrepant values. During the fatigue test, all the groups exhibited infinite lives except G4. Conclusion: Based on the similarity of all the models, it is suggested that all short implants investigated are seemingly viable alternatives for the rehabilitation of atrophic mandibles. However, the 6-mm-long and 8-mm-long implants evinced more favorable mechanical behavior than the 4-mm-long type. Keywords: biomechanics, complete denture, dental implants, finite element analysis

Purpose: To evaluate strain around resilient stud and bar attachments for inclined implants supporting mandibular overdentures during loading and dislodging. Materials and Methods: A mandibular edentulous model was printed using the laser sintering technique. Two vertical implants and two 30-degree distally inclined implants were placed in canine and premolar areas, respectively. Overdentures were attached to the implants with either a resilient stud (Locator, group 1) or a bar/clip (group 2) attachment. Three strain gauges were mounted at the buccal, lingual, and proximal surfaces of each implant. Microstrains were registered during vertical loading and dislodging force applications and compared between attachments (resilient stud and bar) and implant positions (vertical and inclined). Results: For canine implants, bar overdentures recorded significantly higher microstrains than Locator overdentures during vertical loading. For premolar (inclined) implants, Locator overdentures recorded significantly higher microstrains than bar overdentures during vertical dislodging. For both groups (during loading) and the bar overdenture group (during dislodging), canine (vertical) implants showed significantly higher microstrains than premolar (inclined) implants. Conclusion: Within the limitations of this in vitro study, canine (vertical) implants may be at risk of increased stresses during loading if bar attachments are used for vertical and inclined implants supporting mandibular overdentures, and premolar (inclined) implants may be at risk of increased stresses during dislodging if Locator attachments are used. For both attachments, canine implants showed significantly higher microstrains than premolar implants during loading and dislodging. Keywords: attachment, bar, implants, inclined, overdenture, resilient stud, strain

Purpose: To compare the 3D accuracy of copy dentures fabricated using an IOS (IOS copy denture) to that of copy dentures fabricated using the conventional method (conventional copy denture). Materials and Methods: Maxillary and mandibular complete dentures were fabricated and scanned using a high-precision dental laboratory scanner to obtain data (basic data). Optical impressions of the dentures were recorded with the IOS to obtain data (IOS reference dentures). The IOS copy denture was fabricated using a 3D printer after configuring the data using the software. The conventional copy dentures were fabricated by making impressions of the complete dentures and pouring the roomtemperature curing resin into them. The IOS copy dentures and conventional copy dentures were scanned using a highprecision dental laboratory scanner to obtain data. The data obtained were imported into 3D analysis software, and the IOS reference denture, IOS copy denture, and conventional copy denture data were each superimposed on the basic data for 3D evaluation by color mapping and calculation of the concordance rate. Results: Statistically significant differences in the concordance rates were observed between the IOS reference dentures and IOS copy dentures and between IOS copy dentures and conventional copy dentures (P < .05), but not between maxillary and mandibular complete dentures (P > .05). Conclusion: The IOS copy dentures demonstrated greater accuracy than the conventional copy dentures. Keywords: accuracy, copy overdenture, implant overdenture, intraoral scanner, optical impression

Purpose: The purpose of this study was to evaluate the impression accuracy of two implants placed in different orientations and compare the impression accuracy obtained with the dual-arch impression technique using hybrid impression copings and the conventional open-tray impression technique. Materials and Methods: Five mandibular dentiform models were prepared by placing implants in the second premolar and second molar regions in the following different orientations: parallel to each other; 15-degree mesiodistal angulation; 30-degree mesiodistal angulation; 15-degree buccolingual angulation; and 30-degree buccolingual angulation. After making 10 impressions for each model with the open-tray impression technique and dual-arch impression technique with hybrid impression copings, cast models were fabricated for each impression (n = 10). Scan bodies were mounted on the five dentiform models and the fabricated 100 cast models were scanned using a desktop scanner. The three-dimensional deviation of the scan bodies on the cast models was calculated and compared to the reference data from the dentiform models. A two-way analysis of variance was conducted (α = .05). Results: The root mean square deviation values obtained from the implants placed with 30-degree mesiodistal angulation were 93.05 ± 6.21 μm with the open-tray impression technique and 104.01 ± 8.89 μm with the dual-arch impression technique, which were the largest deviation values for both techniques (P < .001). Compared to the open-tray impression technique, the dual-arch impression technique with the hybrid impression copings showed significantly lower accuracy when the angulation between the implants was 15 degrees mesiodistally (P < .001), 30 degrees mesiodistally (P = .016), or 30 degrees buccolingually (P < .001). However, there was no significant difference between the accuracy of the two impression techniques for parallel implants (P = .74). Conclusion: When the two implants were inclined 30 degrees mesiodistally, both implant impression techniques showed the largest deviation and the dual-arch impression technique showed lower accuracy compared to the conventional open-tray impression technique. Parallel placement of implants may improve impression accuracy and enable use of the dual-arch impression technique. Keywords: angulation, dental implant, dental impression materials, dental impression technique, impression accuracy, trueness

Purpose: To evaluate the performance of fixed complete dental prostheses supported by axial and tilted implants after at least 3 years of follow-up. Materials and Methods: An electronic search plus a hand search up to April 2021 was undertaken. Clinical studies were selected using specific inclusion criteria, independent of the study design. The main outcomes were cumulative implant survival rate, marginal bone level changes, and complications, after ≥ 3 years of follow-up. The difference in outcomes between axial and tilted implants and between the maxilla and mandible was evaluated using meta-analysis and the Mantel-Cox test. Results: Out of 824 articles retrieved, 24 were included. In total, 2,637 patients were rehabilitated with 2,735 full prostheses (1,464 maxillary, 1,271 mandibular), supported by 5,594 and 5,611 tilted and axial implants, respectively. In a range between 3 and 18 years of follow-up, 274 implants failed. The cumulative implant survival rate was 93.91% and 99.31% for implants and prostheses, respectively. The mean marginal bone level change was moderate, exceeding 2 mm in only two studies. Marginal bone loss was significantly lower around axial compared with tilted implants (P < .0001), whereas it was not affected by arch (maxilla vs mandible; P = .17). Conclusion: Fixed complete dental prostheses supported by tilted and axially placed implants represent a predictable option for the rehabilitation of edentulous arches. Further randomized trials are needed to determine the efficacy of this surgical approach and the remodeling pattern of marginal bone in the long term. Keywords: axial implants, immediate loading, mandible, marginal bone loss, maxilla, tilted implants

Purpose: To analyze the quality of bone regeneration in fresh sockets using four different materials at different time points. Materials and Methods: A split-mouth randomized clinical trial was designed to evaluate the histologic and histomorphometric characteristics of 82 fresh sockets from 30 patients. One socket per patient healed spontaneously (control), and at least one fresh socket was grafted with a material chosen randomly from a sealed envelope: plateletrich growth factor (PRGF; n = 20 sites), PRGF + autologous bone (n = 9 sockets), autologous bone (n = 10 sites), or PRGF + demineralized freeze-dried bone allograft (DFDBA; n = 13). Biopsy specimens were taken at different time points divided into three assessment groups: short duration (2 to 4 months), intermediate duration (5 to 6 months), and long duration (7 to 12 months). The histologic findings were assessed to quantify the trabeculae pattern, the degree of mineralization, and the quality of bone regeneration. Results: A total of 26 patients with 73 sockets completed the study. Mineralization after a short duration was found to be significantly higher among sockets treated only with autologous bone (47.3% ± 3.6%) or with PRGF+autologous bone (45.1% ± 13.6%). During the intermediate time point, this difference was not observed; also, the control sites were found to have the highest amount of mineralization (37.7% ± 14.9%). After a long duration of wound healing, the PRGF+DFDBA group had the greatest percentage of mineralized tissue (54.7% ± 28.7%), which was significantly higher than the sites treated only with PRGF (30.0% ± 13.2%). Conclusion: From a histologic point of view, the use of autologous graft with or without PRGF seems to be the best strategy for socket regeneration within a short period of time (2 to 4 months). However, the application of PRGF alone inside fresh sockets may interfere with normal bone healing compared with control sites healed spontaneously. Keywords: alveolar ridge preservation, bone healing, histology, platelet-rich plasma, PRGF

Purpose: The “one-abutment, one-time” concept entails the placement of a definitive abutment at the time of implant placement, without removal during prosthesis manufacture, with the aim to promote a safer environment for the periimplant tissues. Identifying surgical and radiographic parameters that can assist with the abutment height selection would facilitate the adoption of the one-abutment, one-time concept. Therefore, the aim of this study was to assess the role of surgical and radiographic parameters as predictive factors for abutment height selection in implant-retained single crowns. Materials and Methods: This prospective study assessed the role of surgical and radiographic measurements in the implant survival and success rates and marginal bone loss in implant-retained single crowns. Implants were placed in both healed sites and extraction sockets, and the distances between the implant platform and alveolar bone crest, implant platform and gingival margin, and buccal gap (when present) were recorded using a straight periodontal probe. Digital radiographs were made at implant placement (T0), abutment height selection (Ta), and 1-year follow-up (Tf), and the distance between the implant platform and the alveolar bone crest (mm) was assessed. Linear regression models and Pearson correlation were used to assess the influence of primary and secondary outcomes on abutment height. Results: A total of 130 implants were placed in 68 patients. The mean surgical distance between the bone crest and the implant platform was 1.71 ± 1.01 mm, and the mean distance from the gingival margin to the implant platform was 3.94 ± 1.90 mm, while at the abutment selection appointment, the mean transmucosal height was 3.58 ± 1.50 mm. A high linear correlation was found between the selected abutment height and two primary outcomes: the radiographic implant platform to alveolar bone crest distance at T0 (r2 = 0.66; P < .001) and the transmucosal height at Ta (r2 = 0.81; P < .001). Conclusion: Radiographic measurements of the distance between the implant platform and the alveolar bone crest at implant placement can serve as an important parameter to select the abutment height for definitive restorations. Keywords: abutment, bone level, dental implant, single crown

Purpose: To evaluate patient satisfaction and prosthetic complications of maxillary conventional dentures and implant overdentures opposing mandibular implant overdentures with different attachments. Materials and Methods: A total of 60 patients with maxillary conventional dentures (maxillary CD) and mandibular two-implant overdentures received four implants in the maxilla. The implants were connected to the maxillary overdentures with a stud attachment (maxillary OD). The participants were classified into three groups according to the type of mandibular overdenture attachment: bar overdentures (BOD, n = 20), resilient telescopic overdentures (TOD, n = 20), and resilient stud/Locator overdentures (LOD, n = 20). Patient satisfaction (using a visual analog scale [VAS] and oral health–related quality of life (OHRQoL)] and prosthetic/soft tissue complications were evaluated for maxillary CD and maxillary OD after 1 year of insertion. Results: LOD showed higher VAS and oral health impact profile (OHIP-14) scores with maxillary CD and maxillary OD than BOD and TOD except for ease of chewing (VAS) and satisfactory diet (OHIP-7). For maxillary CD, TOD showed a significantly higher frequency of prosthetic and soft tissue complications than BOD and LOD. For all groups, maxillary OD showed significantly higher patient satisfaction regarding VAS and OHIP-14 scores, and lower prosthetic and soft tissue complications than the maxillary CD. Conclusion: Locator-retained maxillary overdentures opposing mandibular implant overdentures improved patient satisfaction and reduced prosthetic complications compared to conventional maxillary dentures. Such overdentures are best opposed by Locator-retained mandibular overdentures, as they increase patient satisfaction and reduce prosthetic and soft tissue complications compared to the bar and telescopic attachments. Keywords: patient satisfaction, prosthetic complications, Locator, implant, overdenture, maxillary, mandibular

Purpose: To evaluate the effect of different drilling techniques on implant stability at different time intervals. Materials and Methods: Patients were randomly allotted into three groups based on drilling technique for osteotomy: conventional drilling technique; simplified drilling technique; or modified conventional drilling technique. In 30 patients (n = 10 each group), a total of 44 implants were placed. In the conventional drilling technique, drills with increasing diameters were used. In the simplified drilling technique, only pilot and final-diameter drills were used. In the modified conventional drilling technique, all the drills were used in sequential order in the clockwise direction except the last drill, which was used in the counterclockwise direction. Implant stability quotient was recorded immediately after placing implants and at 1 and 3 months. Statistical analysis was performed with two-way analysis of variance (ANOVA) and Student t test. Results: Two-way ANOVA showed that drilling technique (P < .001) and time (P = .002) did have a statistically significant effect on implant stability quotient. The modified conventional drilling technique showed a drop in secondary implant stability at 1 month that was negligible compared to the other techniques. After 1 month, there was a significant increase in implant stability quotient with the modified conventional drilling technique compared to the conventional drilling technique (P = .001). The least crestal bone loss during 3 months of follow-up was with the modified conventional drilling technique (0.37 ± 0.06). Conclusion: Secondary stability increased with the modified conventional drilling technique in 3 months and showed a negligible drop at 1 month. This novel drilling technique had an early shift from a decrease to an increase in stability pattern, along with the least crestal bone loss at 3 months. Keywords: drilling protocol, implant stability, reverse drilling, secondary stability, simplified drilling

Purpose: Restoring the esthetics of anterior teeth with implants is challenging. This study aimed to evaluate the esthetic outcome of interproximal papilla between implant-restored unilateral and bilateral maxillary central incisors. Materials and Methods: A total of 56 adults with implant restorations in the maxillary central incisors were enrolled, including 40 cases of unilateral incisors and 16 cases of bilateral incisors. Photographic and radiographic assessments were performed, and patient-reported esthetic satisfaction was collected. Results: The papilla index (PI) in the unilateral group was superior to that in the bilateral group (P = .002). Patients in the two groups reported equal satisfaction regarding the final esthetic outcome (P = .470). Statistically significant differences were noted between the two groups in papilla height (P = .000), implant-implant or implant-tooth distance (P = .002), and vertical distance from the implant platform to the bone crest (P = .000). In the bilateral group, tested variables were not correlated with PI by nonparametric Spearman correlation. In the unilateral group, the multivariate binary logistic regression model showed that incomplete papilla fill was associated with abutment type (OR = 0.019), implant-tooth distance (range, 2.1 to 6.2 mm; OR = 6.435), and distance from the bone crest to the contact point (range: 3.5 to 6.9 mm; OR = 4.589). Conclusion: In implant-restored maxillary central incisors, PI in the unilateral group was superior to that in the bilateral group. In the bilateral group, no clinical variable was correlated with PI. In the unilateral group, the risk of incomplete papilla fill was reduced by the customized zirconia abutment and was increased by the larger implant-tooth distance and higher distance from the bone crest to the contact point. Keywords: dental esthetics, dental implants, incisor, interdental papilla, personal satisfaction, risk factors