The International Journal of Oral & Maxillofacial Implants, 01/2021

Purpose: To assess the postoperative complications and outcome (implant survival) of quad zygomatic implants inserted in patients with edentulism and severely atrophic maxillae. Materials and Methods: Two independent reviewers conducted an electronic search of the literature (PubMed, Scopus, EBSCO, Web of Science) from January 2000 to February 2019. The inclusion criteria were articles published in English reporting data of at least five patients with severely atrophic edentulous maxillae undergoing placement of four zygomatic implants without additional insertion of standard implants, with a minimum of 6 months of follow-up. Data extracted included number of patients, characteristics of the maxillary defect, number of zygomatic implants, implant details, surgical procedure, prosthetic rehabilitation, postoperative complications, survival rate, and length of follow-up after definitive prosthesis delivery. Results: Eleven studies with 166 patients were included. The heterogeneity among studies was not significant. The pooled incidence rates of complications were as follows: sinusitis 12% (95% confidence interval [CI]: 4% to 23%), malposition and surgical guiding failure 11% (95% CI: 3% to 21%), local infection/injury 10% (95% CI: 3% to 18%), and prosthetic complications 5% (95% CI: 0% to 13%). The implant survival rate ranged between 95.8% and 100%, and the pooled implant survival rate in the meta-analysis was 98% (95% CI: 97% to 99%). Conclusion: Quad zygomatic implants inserted in patients with severely atrophic edentulous maxillae have a high implant survival rate, but the incidence of complications should not be underestimated. Keywords: alveolar bone loss, dental implants, edentulous/rehabilitation, jaw, meta-analysis, systematic review, zygoma/ surgery

Purpose: This study aimed to assess the survival rate, marginal bone levels, and prosthetic success of short implants when placed in posterior areas of severely reabsorbed mandibles. Materials and Methods: A systematic review was performed of all randomized controlled trials with at least 10 patients with a control group where bone augmentations were performed that were published between January 2015 and February 2020. From 77 pertinent studies, 14 full-text publications were studied, and 6 studies fulfilled the inclusion criteria. Results: The implant survival rates of short dental implants ranged from 92% to 96.9% with a follow-up from 1 to 5 years, and the prosthetic success rate ranged from 90% to 100% during the same follow-up. The mean marginal bone level values of involved short implants ranged from –0.51 to –2.30 mm. Conclusion: The obtained data showed that short dental implants are a valid therapeutic choice to rehabilitate severe mandibular atrophy in the medium to long term. Keywords: guided bone regeneration, mandibular atrophy, short dental implants, short implants

Purpose: The aim of this work was to evaluate osseointegration of endosteal implants with two different surface treatments at early stages (~3 weeks) in the tibia of healthy and ovariectomized rabbits. Materials and Methods: The study comprised 10 adult New Zealand female rabbits (Oryctolagus cuniculus; 6 months and 3.0 ± 0.5 kg). Five animals were subjected to bilateral ovariectomy to mimic osteoporotic-like conditions, and the remaining rabbits (n = 5) served as the healthy control group. After 3 months, specimens from the ovariectomized and control groups were subject to implant placement in both tibiae, using two different types of surface treatment. A total of 36 implants were placed, n = 18 acid-etched and n = 18 anodized. After 3 weeks, euthanasia of the animals was performed, and samples were obtained for processing. Bone-to-implant contact and bone area fraction occupancy were quantified to evaluate the osseointegration parameters around the implant surface and within the thread area, respectively, and nanoindentation tests were performed to determine elastic modulus and hardness of the new bone. Both analyses were performed on the entire implant (total), as well as individually within the cortical and bone marrow cavity area. Results: All animals were evaluated with no signs of infection or postoperative complications. The total bone-to-implant contact and bone area fraction occupancy results, independent of surface treatment, yielded significant differences between the ovariectomized and control groups (P = .002 and P < .001, respectively). In the marrow cavity, analyzing the surface treatments independently as a function of bone condition, the only differences detected were in the anodized treatment (P = .04). Regarding the elastic modulus, differences were detected only with the anodized implants between the ovariectomized and control groups (P = .015). Conclusion: At 3 weeks after implant placement, there were better osseointegration values of the implants in the healthy control group compared with the ovariectomized group independent of surface treatment. Also, specifically in the medullary region of the rabbit tibia, the acid-etched implants had more uniform osseointegration values in conditions of low-quality bone in comparison to the anodized implants, histomorphometrically and biomechanically. Keywords: dental implants, osseointegration, osteoporosis, surface treatment

Purpose: The aim of this in vitro study was to evaluate the mechanical behavior regarding dynamic fatigue of different implant-abutment connections and the unitary indication of abutments for all regions of the mouth. Materials and Methods: This experimental study developed according to international standards (ISO 14801:2007) was performed using five types of implants and abutments: G1—external hex smart implant and 17-degree universal abutment (EHS); G2—cortical external hex implant and 17-degree universal abutment (EHTi); G3—internal hex implant and 30-degree universal abutment (IH); G4—Morse taper implant (11.5 degrees) and 17-degree universal abutment (MT11.5); and G5— Morse taper implant (16 degrees) and 30-degree universal abutment (MT16). A 15-Hz cyclic loading was applied to the specimens with the maximum number of cycles set at 5 × 106. Success was defined when three samples supported 5 million cycles without failure. The maximum load supported from each group after dynamic loading was recorded. The Spearman correlation and the Lowess method were used to analyze the correlation between the number of cycles and the applied load, and the Kruskal-Wallis and Nemenyi tests were used for comparison between the abutments when reaching 5 million cycles. Results: There was a negative correlation (r < 0.00) and significant difference (P < .05) between the number of cycles and the load for each type of implant and abutment. The load values supported by each group after cyclic loading to achieve 5 million cycles were as follows: EHS, 225 N; EHTi, 215 N; IH, 220 N; MT11.5, 210 N; and MT16, 240 N. The MT16 implant-abutment assembly presented a significantly higher load (P = .024) than the MT11.5 implant-abutment assembly. Conclusion: All implant-abutment connections investigated in this study resisted average occlusal force values reported as acceptable in the literature and may be indicated for any region of the mouth. Keywords: abutment, biomechanics, compressive loading, dental implants

Purpose: The purpose of this in vitro study was to evaluate the load-to-fracture values of cement-, screw-, and multiscrew-retained abutments for implant-supported fixed partial dentures (FPDs). Materials and Methods: Thirty-six implants with a diameter and length of 4.5 and 13 mm, respectively, were used to prepare 18 samples of FPDs. Based upon the variations on abutment design, the FPDs were divided into three categories as follows: cement-retained, screw-retained, and multiunit screw-retained abutments. Using a chewing simulator, cyclic loads of 1,250,000 load cycles with a load of 70 N were applied on all samples to simulate 5 years of human functional chewing. The samples were loaded until failure using an electromechanical test machine. Sample-size estimation was done, and fracture-load values were recorded as means and corresponding standard deviations; group comparisons were done using one-way analysis of variance and Tukey post hoc tests. A P value < .01 was considered as an indicator of statistical significance. Results: The fracture-load values for cement-, screw-, and multiunit screw-retained abutments were 2,109.2 ± 139.6 N, 3,888.8 ± 70 N, and 3,319.4 ± 218.9 N, respectively. The load-to-fracture values were significantly higher in screw-retained abutments (3,888.8 ± 70 N; P < .001) than in cement-retained (2,109.2 ± 139.6 N) and multiunit screw-retained abutments (3,319.4 ± 218.9 N). Conclusion: Screw-retained implant-supported FPDs withstand higher occlusal forces compared with cement- and multiunit screw-based retention techniques. However, the results should be cautiously interpreted, as they were based on a relatively small sample size. Keywords: abutment, fixed partial denture, fracture load, implant

Purpose: Short dental implants serve as a valuable alternative for patients with limited bone height. Immediate or early provisionalization facilitates a more physiologic environment for the gingival tissues to be modeled. The purpose of this meta-analysis was to systematically review and evaluate the implant survival and marginal bone loss with immediate and early loading protocols of short dental implants (≤ 6 mm). Materials and Methods: A literature search (electronic and manual) was conducted to identify studies with a focused PICO question: “In patients with short dental implants, does loading time affect treatment outcomes?” Studies using an immediate or early loading protocol for restoration of short implants with a mean follow-up of at least 1 year, and refraining from the use of advanced surgical procedures (sinus floor elevation, bone augmentation), were included. After evaluating patient selection and outcome reporting biases, a meta-analysis was conducted to assess implant survival and bone loss for studies fulfilling the inclusion criteria. Bone loss differences between immediate and early loading protocols were evaluated by Student t test, and Spearman correlation analysis was used to analyze the trends between crown-to-implant (C/I) ratio and bone loss. Results: A total of 396 studies with patients receiving short implants (≤ 6 mm) with immediate or early prosthetic loading protocols were identified. For the 7 included studies, the pooled implant survival rate for 322 implants with a follow-up ranging from 1 to 10 years (5 years) was 91.63% (95% CI: 88% to 94%), with a mean bone loss effect estimate of 0.52 ± 0.1 mm (z = 3.07, P < .002). The differences observed in the mean bone loss for studies using immediate loading as opposed to early loading were not statistically significant. A moderate but significant positive correlation was observed between the C/I ratio and mean bone loss levels (r = 0.67, P = .02). Conclusion: Short implants with immediate or early loading protocols have satisfactory long-term treatment prospects with satisfactory implant survival rates and minimal bone loss. Keywords: bone loss, dental implants, humans, short, success, survival

Purpose: The aim of this study was to test in vitro the bacterial microleakage at the Morse taper implant-abutment connection with switched platform subjected to functional load and thermocycling. Materials and Methods: A total of 48 Morse taper implant-abutment connections with switched platforms (12 implants per group) were used. The abutments were attached to implants and presented in four groups: group 1, control; group 2, subjected to thermocycling; group 3, subjected to cyclic compressive loading; and group 4, subjected to thermocycling and cyclic compressive loading. All groups were then inoculated in Eppendorf tubes including three types of bacterial suspensions: Enterococcus faecalis, Staphylococcus aureus, and Pseudomonas aeruginosa for 7 and 14 days to detect possibility of bacterial infiltration from outside to the internal chamber of the implant. Results: Implants not exposed to cyclic loading and thermocycling (group 1) and those exposed to thermocycling (group 2) exhibited no infiltration of E faecalis, S aureus, and P aeruginosa from outside to the inner chamber of the implant, while infiltration of P aeruginosa was only observed in implants subjected to cyclic loading only (group 3) and those subjected to cyclic loading in conjunction with thermocycling (group 4). Conclusion: Microbial leakage at the implant-abutment connection is influenced by the applied load alone and in combination with thermocycling; however, E faecalis and S aureus did not leak at the implant-abutment connection even under these circumstances. Only P aeruginosa infiltrated inside the implant-abutment connection, which might be caused by its swarming motility. Keywords: bacterial leakage, dental implant, Morse taper connection, switched platform

Purpose: This study evaluated the mechanical behavior of different configurations of the All-on-4 treatment concept designed with straight short (6-mm-length), straight standard (11-mm-length), or tilted standard (30-degree angled; 11-mm-length) posterior implants. Materials and Methods: The All-on-4 configurations were performed in atrophic mandible models and consisted of anterior straight standard and posterior tilted standard implants (H1 model), anterior straight standard and posterior straight short implants (H2 model), and anterior and posterior straight standard implants (H3 model). Three oblique forces of 100 N were simulated in the posterior region of the prosthetic bar. The values of stress were obtained for the ductile materials using the von Mises equivalent stress (σvm) criteria. The stress peaks in the periimplant bone crest were measured by the maximum (σmax) and minimum (σmin) principal stresses. The two-way analysis of variance (two-way ANOVA) and Tukey post hoc tests determined significant differences (P < .01) of stress values among the ductile materials (implant and prosthetic components). Results: The use of tilted standard posterior implants (H1 model) showed the lowest values of σmax and σmin in the posterior region of the peri-implant bone area. On the other hand, the use of straight short (H2 model) or straight standard (H3 model) posterior implants significantly reduced the von Mises mean stresses in the bar screws, abutments, and abutment screws (P < .01). Conclusion: The higher odds of technical failures (screw fracture/loosening) may be expected when the All-on-4 configuration is performed with tilted standard posterior implants. Also, peri-implant bone overload may occur when the All-on-4 design is performed with straight short or straight standard posterior implants in atrophic mandibles. Keywords: dental implants, finite element analysis, mechanical stress, short implants

Purpose: Gingiva-resident memory B cells found recently in healthy periodontal tissue may play important roles in maintaining homeostasis against bacterial plaque. Whether resident memory B cells exist in healthy peri-implant tissue and how they respond in peri-implantitis lesions are of interest. The aim of this study was to preliminarily investigate whether memory B cell activities are related to inflamed or healthy peri-implant status. Materials and Methods: Patients with peri-implantitis or healed implants were recruited. The gingiva samples were collected and divided into inflamed (n = 4), treated (n = 4), and healed (n = 3) groups, followed by a flow cytometry analysis staining with CD3, CD19, CD27, CD38, and RANKL. The biopsy samples were also cryo-embedded for immunofluorescent double staining of CD19 and CD27. Results: CD27+ CD38+ ASC comprised 83.3% ± 3.3% of the total B cells in the inflamed group, and this proportion in the treated group was reduced to 44.5% ± 13.4%. The proportion of CD27+ CD3+ T cells was found to be unchanged between the inflamed and treated groups. Immunofluorescent staining indicated that CD19+ CD27+ population infiltrated peri-implant connective tissue. RANKL was expressed by almost all B cells and a portion of T cells in the inflamed group, while the proportions of RANKL+ B and T cells were significantly reduced in the treated group. Barely any memory B cells were detected in the healed group. Conclusion: Memory B cells were markedly activated in peri-implantitis and responded to the suprastructure removal treatment. The lack of gingiva-resident memory B cells in the clinically healed implants serves as a hint for the weakness of peri-implant tissue against bacterial plaque. Keywords: B lymphocyte, host response, peri-implantitis

Purpose: To examine the effect of the attachment features (abutment height, retention, and freedom of rotation) of implant overdentures on the bending strain around implants under an overdenture. Materials and Methods: Mandibular and maxillary edentulous models were fabricated and covered with silicone rubber. Strain gauges were attached to the four sides of each implant. Two implants (tissue-level implant, 4.1-mm diameter, 10-mm length) were placed bilaterally in the area between the mandibular canines and lateral incisors. A maxillary conventional denture and a mandibular overdenture were made to fit the edentulous models. Three levels of peri-implant bone resorption were created sequentially: no bone resorption, 0.8 mm, and 1.5 mm. Three kinds of attachments (magnetic, stud, and ball attachments) were used. Bending strains generated from a 98-N occlusal load through the maxillary denture were measured using a sensor interface, and the data were analyzed using the Kruskal-Wallis and Bonferroni tests. Multiple regression analysis was used to find the relationship between independent variables (peri-implant bone resorption level, abutment height, retention, and freedom of rotation) and the dependent variable (bending strain). Results: For all attachment types, the bending strains were smallest with no bone resorption and largest with 1.5-mm bone resorption (P < .05). Multiple regression analysis showed that abutment height had the greatest impact on the reduction of bending strain (beta = .413), followed by freedom of rotation (beta = −.349), and retention (beta = .107). Conclusion: Low abutment height, large freedom of rotation, and low retention can minimize bending strain around implants. Keywords: biomechanics, overdenture, prosthodontics

Purpose: Beneficial aspects of short and ultrashort antibiotic administration protocols could be clinically correlated to the reduced side effects on the gastrointestinal microflora. The aim of this Consensus Conference was to establish the necessity of an antibiotic prophylaxis and its dosage to reduce the risk of early implant failure in healthy (ASA 1 or 2), periodontally healthy patients, undergoing basic dental implant surgery (straightforward cases). Additionally, the need for an antiseptic protocol, used before and after the implant surgery, was evaluated. Materials and Methods: Active members of the Italian Academy of Osseointegration (IAO), together with several worldwide-recognized key opinion experts in the field of microbiology, implant dentistry, and infectious diseases, were participants at this Consensus Conference. Two systematic reviews were carried out, before the Consensus Conference, and their results discussed in order to give guidelines on the administration of an antibiotic/antiseptic prophylaxis in implant surgery. The systematic reviews covered the following topics: (1) the use of antibiotics to reduce both implant failure rate and peri-implant infections in healthy patients and (2) the use of chlorhexidine compositions capable of reducing complications in patients undergoing surgical interventions. Results: The main statements reached by the assembly were as follows: (1) Rinsing with chlorhexidine is highly recommended before and after implant surgery to minimize the bacterial load. (2) A single dose of antibiotics in straightforward cases is recommended. (3) In complex cases (long surgical time, regeneration procedures), it is advisable to continue the antibiotic administration. Conclusion: This Consensus Conference advocates the administration of a unique dose of antibiotics in straightforward implant cases combined with the use of chlorhexidine. Keywords: antibiotics, dental implants, surgery

Purpose: This in vitro study aimed to determine the efficacy of a damping capacity assessment in evaluating the implant stability in a simulated peri-implant bone loss model. Materials and Methods: The same type of implant was placed sequentially in 0.5-mm-depth increments in polyurethane bone of a constant density, resulting in 11 specimens with varying surrounding bone levels. The implant stability was evaluated by a damping capacity assessment consisting of six consecutive impacts in one set. The damping results, including the contact time and stability index, were measured by three repeated sets of stability tests for each specimen. All implant micromotions were recorded in real time using a laser scanning vibrometer during these stability tests. The micromotions were analyzed in terms of three parameters: maximum displacement, expected mobility, and vibration frequency. Additionally, two other stability indices were acquired three times each for reference. Pearson correlation analysis was used to confirm the correlations among all the variables; P < .05 was considered statistically significant. Results: As the peri-implant bone level increased, the contact time results decreased gradually from 502 to 290 μs, and the stability index increased from 55 to 78. The implant micromotions of all specimens showed a damped sine waveform graph, which can be divided into impact displacement and self-vibration patterns by the contact end points. As the implant stability increased, these contact end points converged toward the third peak, the maximum displacement and expected mobility decreased, and the vibration frequency increased (ρ = –0.85, –0.88, and 0.99, respectively). Two other stability indices reflected the implant stability due to peri-implant bone loss. The statistical analysis indicated significant correlations among all measured variables; in particular, the three stability indices exhibited high correlations with each other (ρ = 0.99, –0.99, and –1.00, respectively). Conclusion: Within the limitations of this in vitro study, the implant stability measured by a damping capacity assessment was suitable for investigating the extent of implant micromotions, which were determined by 0.5-mm horizontal changes in the peri-implant bone level. Keywords: damping capacity assessment, dental implant, implant stability, laser scanning vibrometer, micromotion, resonance frequency analysis

Purpose: Peri-implantitis, a potentially progressive disease that occurs in patients with dental implants, is more aggressive than periodontal lesions, which makes the prevention of peri-implantitis an important priority. Due to problems in the early detection of peri-implantitis, there is an urgent need for discovering novel biologic molecules with the ability of early diagnosis. The goal of this study was to profile the microRNA content of saliva samples collected from patients with titanium-aluminum-vanadium alloy dental implants who experienced peri-implantitis and to find potential diagnostic markers for detection of this disease. Materials and Methods: The microRNA expression profiles of eight saliva samples (four collected from patients with peri-implantitis, four collected from patients who have successful implants) were investigated, and the deregulation of select microRNAs was further confirmed using quantitative polymerase chain reaction. Results: The expressions of 179 microRNAs were found as deregulated in the saliva of peri-implantitis patients in comparison to controls. Then, downregulation of miR-4484 was confirmed in the saliva of peri-implantitis patients in a larger validation cohort. Also, 40% of non-peri-implantitis patients and 78% of peri-implantitis patients had significantly decreased miR-4484 expression in saliva samples collected after 4 to 6 months subsequent to implant placement compared with samples collected before implant placement. Conclusion: Considering these findings, microRNA content of saliva might be proposed as a plausible source for the early diagnosis of peri-implantitis, where miR-4484 might serve as an encouraging early diagnostic biomarker. Keywords: dental implant, microRNAs, miR-4484, noncoding RNAs, peri-implantitis

Purpose: The aim of this retrospective study was to determine if penicillin allergy and/or clindamycin therapy may contribute to a higher incidence of postsurgical infections after bone augmentation. Materials and Methods: This retrospective study analyzed patients between 2014 and 2019 who received bone augmentation procedures (socket grafting [SG]; ridge augmentation [RA]) prior to placement of dental implants. All the grafting procedures were performed under preoperative and postoperative oral antibiotic coverage with either amoxicillin or clindamycin for patients who reported penicillin allergy. Infections associated with the bone augmentation procedures were recorded. Results: In this study, 1,814 patients received 2,961 bone augmentation procedures (2,530 SG, 431 RA). In the 2,530 SG procedures, 270 (10.7%) were associated with a penicillin allergy. Infections occurred in 91 of the 2,530 SG sites (3.6%). However, the infection rate was 10.7% (29 SG sites) for clindamycin and only 2.7% (62 SG sites) for amoxicillin (P < .02). In the 431 RA procedures, 71 (16.5%) were associated with a penicillin allergy. Overall infections occurred in 31 of the 431 sites (7.2%). However, the infection rate was 22.5% (16 RA sites) for clindamycin and only 4.2% for amoxicillin (15 RA sites; P < .01). Penicillin-allergic patients taking clindamycin demonstrated a higher risk of infection with a risk ratio of 6.9 (95% CI) and 4.5 (95% CI) compared with nonallergic patients taking amoxicillin for RA and SG, respectively. Conclusion: Penicillin allergy and the use of clindamycin following SG and RA procedures was associated with a higher rate of infection and may be a risk factor for bone augmentation complications.

Purpose: To present a case series treated by inferior meatal antrostomy as a prophylactic maneuver after the placement of zygomatic implants to decrease the risk of sinusitis. Materials and Methods: All patients undergoing zygomatic implant placement using the lower meatal antrostomy protocol between June 2011 and March 2019 at the Department of Oral and Maxillofacial Surgery, Universidad El Bosque, were included. Patients were evaluated after 12 months of the procedure using clinical and radiologic criteria described by Kuriyama and Reiskin. Results: Forty-eight patients were included, in whom 184 implants were placed. Complications were as follows: paresthesia (6.2%), orosinusal fistula (4.1%), skin infection (2.1%), and loss of the implant (1.6%). There were no cases of sinusitis. Conclusion: This study provides evidence that the technique is effective and should be considered because of its simplicity. The inferior meatal antrostomy has been proven to be a simple, effective, and reliable technique to decrease the risk of sinusitis associated with the placement of zygomatic implants. Keywords: case-control study, implant, oral and maxillofacial, surgery, zygomatic

Purpose: The clinical long-term outcomes of short implants are controversial. The aim of this study was to perform a long-term evaluation of short implants in posterior partially edentulous areas under various conditions. Materials and Methods: This retrospective study was conducted with patients who had received 5- to 8-mm short implants to avoid bone grafts and spare anatomical structures between November 2005 and February 2014. Clinical outcomes (primary and secondary stability, marginal bone loss, and success and survival rates) were analyzed according to predictor variables of surgical procedure (submerged vs nonsubmerged), crown/implant ratio (1.5 and 2.0), type of prosthetic (single vs splinted crown), and arch location (maxilla vs mandible). The success rate was evaluated according to Albrektsson’s criteria, and 5- and 10-year cumulative survival rates were calculated using Kaplan-Meier survival curves. Results: A total of 148 patients (73 men, 75 women, mean age: 59.2 years) and 225 short implants were analyzed in this study. Over an average period of 6.21 ± 3.09 years, marginal bone loss was 0.43 ± 1.01 mm, and overall success and survival rates were 93.33% ± 25.0% and 97.78% ± 14.77%, respectively. Cumulative 5- and 10-year survival rates were 99.05% ± 0.65% and 96.72% ± 1.62%, respectively. Conclusion: Short implants (≤ 8 mm) in posterior edentulous areas showed comparable long-term outcomes of marginal bone loss and success and survival rates with conventional implants regardless of other clinical variables such as surgical procedure, crown/implant ratio, prosthetic type, and arch location. Keywords: alveolar bone loss, dental implant, implant-supported dental prostheses, prognosis, survival rate

Purpose: To evaluate the clinical and radiographic outcomes of endoscope-assisted maxillary sinus floor elevation with platelet-rich fibrin grafting and simultaneous implant placement (PESS) in atrophic maxillae. Materials and Methods: Twenty-three implants were placed to rehabilitate atrophic maxillae. Patient satisfaction was measured with a visual analog scale (VASpain). CBCT was taken to assess the bone changes for the elevated sites. Results: Twenty-two of 23 implants fulfilling the survival criteria represented a 1-year survival rate of 95.65%. The VASpain score decreased with time. The residual bone height was 4.45 ± 1.44 mm. The elevation height was 6.72 ± 1.84 mm. The definitive restoration was completed in the 4th month postsurgery. The peri-implant bone level value was 6.04 ± 2.30 mm, 6.32 ± 2.25 mm, and 6.71 ± 1.97 mm at the 3rd, 9th, and 15th month postsurgery. The crestal bone level value decreased by 0.22 ± 0.56 mm from the 3rd month to the 15th month postsurgery (P > .05). Bone mineral density increased with time at the neck, middle, and root site of implant. Conclusion: PESS in the maxilla resulted in predictable peri-implant bone formation. This strategy is a relatively safe and effective approach with less invasion, which provides new insights into the choice of implant treatment plans. Keywords: growth factors, sinus floor elevation, surgical techniques

Purpose: This study aimed to assess the radiographic, esthetic, and periodontal outcomes after 1 year of implant placement in compromised fresh extraction sockets in the esthetic zone using vestibular socket therapy. Materials and Methods: Implants were placed in type 2 sockets using vestibular socket therapy, which includes immediate implant placement, vestibular incision, and cortical bone shield stabilization, along with filling the socket gap with particulate bone graft, then sealing the socket orifice with a customized healing abutment in one visit. A 6-day protocol of antimicrobial therapy for treating sockets with active infection was also described. Assessment included measuring bone height and labial plate thickness at three levels at baseline and after 1 year, in addition to pink esthetic score and periodontal parameters (modified sulcus Bleeding Index and peri-implant probing depth) after 1 year. SPSS was used to calculate descriptive statistics of outcome measures. Results: All 16 implants used in the study showed success. There was a significant increase of bone height and bone thickness at the middle and crestal thirds (mean [SD] gain = 6.08 [3.07], 1.65 [0.91], and 1.18 [1.51]). The mean (SD) pink esthetic score was 12.63 (1.71), the mean (SD) modified sulcus Bleeding Index was 1.19 (0.40), and the mean (SD) peri-implant probing depth was 1.97 (0.46) mm. Conclusion: Vestibular socket therapy was successfully used in compromised sockets with optimum radiographic, esthetic, and periodontal outcomes in addition to minimizing treatment time and number of surgical interventions. The 6-day protocol was able to eliminate infection and prepare sockets for implant placement. Keywords: active infection, defective socket, esthetic zone, immediate implant, labial bone plate, midfacial recession

Purpose: Using panoramic radiograph and CBCT to compare the measurement errors of the residual bone height in the same site before implant placement in the posterior maxilla and endo-sinus bone gain after osteotome sinus floor elevation without grafting, and to evaluate endo-sinus bone augmentation before stage-two surgery with CBCT. Also, some related factors of new bone formation in the sinus were analyzed, such as small bone block elevated by osteotome at the implant apex intraoperatively. Materials and Methods: Patients were enrolled in the retrospective study; dental implants were placed in the maxillary posterior region using osteotome sinus floor elevation without grafting. The panoramic radiograph and CBCT were taken preoperatively, immediate postoperatively, and before the stage-two surgery. Endo-sinus bone augmentation was evaluated. A generalized linear model was made to explore the related factors of endo-sinus bone gain. Also, some clinical indexes, such as sinus membrane perforation rate, implant success, and failure criteria were assessed. Results: One hundred two dental implants were inserted in 91 patients. Preoperatively, the mean residual bone height was 8.53 ± 1.76 mm and 7.87 ± 1.45 mm measured using a panoramic radiograph and CBCT, respectively, with significant statistical differences (P < .05). Endo-sinus bone gains of 1.31 ± 1.05 mm by panoramic radiograph and 1.80 ± 1.72 mm by CBCT were observed, with statistically significant differences (P < .05). The final endosinus bone gain was positively correlated with the implant protrusion length at baseline without any other relevant factors, such as elevated small bone block. Conclusion: Measurement errors could be relatively minimized when using CBCT. Using the osteotome sinus floor elevation technique without grafting, approximately 2 mm of endo-sinus bone could be acquired. The final endo-sinus bone gain was positively correlated with implant protrusion length at baseline. Small bone block elevated intraoperatively did not gain more endo-sinus bone. Keywords: cone beam computed tomography, dental implant, endo-sinus bone gain, sinus floor augmentation

Purpose: This study sought to define the tissue responses at different implant-abutment interfaces by studying bone and peri-implant mucosal changes using a 5-year prospective randomized clinical trial design study. The conus interface was compared with the flat-to-flat interface and platform-switched implant-abutment systems. Materials and Methods: One hundred forty-one subjects were recruited and randomized to the three treatment groups according to defined inclusion and exclusion criteria. Following implant placement and immediate provisionalization in healed alveolar ridges, clinical, photographic, and radiographic parameters were measured at 6 months and annually for 5 years. The calculated changes in marginal bone levels, peri-implant mucosal zenith location, papillae lengths, and peri-implant Plaque Index and bleeding on probing were statistically compared. Results: Forty-eight conus interface implants, 49 flat-to-flat interface implants, and 44 platform-switched implants were placed in 141 subjects. Six platform-switched interface and eight flatto- flat interface implants failed, most of them within 3 months. After 5 years, 33 conical interface, 28 flat-to-flat interface, and 27 platform-switched interface implants remained for evaluation. Calculation of marginal bone level change showed a mean marginal bone loss of –0.16 ± 0.45 (–1.55 to 0.65), –0.92 ± 0.70 (–2.90 to 0.20), and –0.81 ± 1.06 (–3.35 to 1.35) mm for conical interface, flat-to-flat interface, and platform-switched interface implants, respectively (P < .0005). The peri-implant mucosal zenith changes were minimal for all three interface designs (0.10 mm and +0.08 mm, P > .60). Only 16% to 19% of the surfaces had presence of bleeding on probing, with no significant differences (P > .81) between groups. Interproximal tissue changes were positive and similar among the implant interface designs. Conclusion: Over 5 years, the immediate provisionalization protocol resulted in stable peri-implant mucosal responses for all three interfaces. Compared with the flat-to-flat and platform-switched interfaces, the conical interface implants demonstrated significantly less early marginal bone loss. The relationship of marginal bone responses and mucosal responses requires further experimental consideration. Keywords: esthetics, immediate loading, marginal bone levels, peri-implant mucosa, randomized controlled clinical trial

Purpose: Abutment screw loosening is a frequently encountered prosthetic complication in implant dentistry. Due to the detection of preload loss soon after initial torque application, abutment screw retightening 10 minutes after initial tightening has been recommended. The aim of this clinical study was to assess preload maintenance in the abutment screws of single posterior implants after 1 month of use by employing screw-cement-retained prostheses and a clinical assessing method, with the ultimate goal of helping to improve the clinical workflow of implant-based restorations. Materials and Methods: In total, 158 patients treated using three implant systems were divided randomly into two groups in which abutment screws were and were not retightened, respectively, approximately 10 minutes after initial torque application. Screw-cement-retained prostheses, which permitted the assessment of abutment screw preload maintenance and screw retightening after 1 month of use, were used. Preload loss at 1 month was defined as the failure to achieve the torque recommended for the abutment screws after 90-degree clockwise rotation of the screwdriver. The data were analyzed using binary logistic regression, with a significance level of P ≤ .05. Results: No preload loss was detected 10 minutes after initial screw tightening. Preload loss was detected in 16 (10.13%) cases at 1 month after initial tightening, with no significant difference according to the implant system used, the presence or absence of retightening at 10 minutes after initial tightening, or implant position (premolar or molar). Conclusion: Under the experimental conditions of this study, abutment screws in some bone-level, internal tapered–connection, platform-switching implant systems showed preload loss at 1 month after abutment placement for single posterior implant-based restorations, regardless of implant system or whether abutment screws had been retightened 10 minutes after abutment placement, or implant position (premolar or molar). It is necessary to retorque the abutment screws 1 month after initial torque. The screw-cement-retained prostheses used in this study permit abutment screw retightening at that time and have advantages over traditional methods. Keywords: dental implant, dental prosthesis, preload, settling effect, torque

This case report demonstrates the use of dynamic navigation guidance for bone reduction. Information about smile line position incorporated in a virtual plan and accurate transfer to the surgical field enhances the predictability of the treatment. A virtual wax-up was made, and implant positions along with bone reduction were planned accordingly. Residual teeth in the maxilla were extracted, and bone reduction and zygomatic implant placement were assisted by surgical navigation, while conventional implants were placed using the surgical template, followed by immediate loading. When surgical navigation is used for implant placement, navigated bone reduction can easily be incorporated in the workflow. The accuracy of bone reduction was evaluated together with the accuracy of two zygomatic implants assisted by a navigation system and four conventional implants assisted by a static template. The mean deviation between planned and performed bone reduction was 1.3 ± 0.39 mm (range: 0.8 to 1.7 mm). The accuracy of this procedure corresponds to the accuracy of guided implant placement and can be considered reliable after confirmation through clinical trials. Keywords: accuracy, bone reduction, dynamic navigation, full-arch rehabilitation, immediate loading, zygomatic implant