Pages 1069, Language: English
Pages 1072-1075, Language: English
Pages 1077-1082, Language: English
Purpose: The objective of this study was to develop a deep convolutional neural network (CNN) that would identify the brand and model of a dental implant from a radiograph.
Materials and Methods: A data augmentation procedure provided a total of 1,206 dental implant radiographic images of three different brands for six models (Nobel Biocare NobelActive [NNA] and Brånemark System [NBS], Straumann Bone Level [SBL] and Tissue Level [STL], and Zimmer Biomet Dental Tapered Screw-Vent [ZTSV] and SwissPlus [ZSP]). They were divided into a test group (n = 241; 19.9%) and a training and validation group (n = 965; 80%). Preprocessing and transfer learning were applied to a pretrained GoogLeNet Inception CNN network. The accuracy, sensitivity, specificity, positive predictive value, negative predictive value, receiver operating characteristic (ROC) curve, and area under the ROC curve (AUC) of the CNN model were evaluated.
Results: The diagnostic accuracy was 93.8% (95% CI: 87.2% to 99.4%), the sensitivity was 93.5% (95% CI: 84.2% to 99.3%), the specificity was 94.2% (95% CI: 83.5% to 99.4%), the positive predictive value was 92% (95% CI: 83.9% to 97.2%), and the negative predictive value was 91.5% (95% CI: 80.2% to 97.1%). The deep CNN algorithm achieved an AUC of 0.918 (95% CI: 0.826 to 0.973) on NNA, 0.922 (95% CI: 0.831 to 0.964) on NBS, 0.909 (95% CI: 0.844 to 0.982) on SBL, 0.890 (95% CI: 0.783 to 0.945) on STL, 0.931 (95% CI: 0.867 to 0.979) on ZTSV, and 0.911 (95% CI: 0.811 to 0.957) on ZSP.
Conclusion: The deep CNN model had a very good performance in identifying a dental implant from a radiograph. A huge and varied database of radiographs would have to be built up to be able to identify any dental implant.
Keywords: artificial intelligence, deep learning, dental implants, dental radiography
Pages 1083-1089, Language: English
Purpose: Intraoral bone blocks from the external oblique are the gold standard for alveolar ridge bone grafting, but the limited amount of available bone limits their use for larger defects. The objective of this study was to compare whether different graft designs of intraoral bone blocks could affect the amount of bone gain.
Materials and Methods: In this in vitro study, 20 pig jaws were used to harvest bone blocks and subsequently augment single-wall bone defects. Each bone graft was first used as a full block, and then the same block was divided lengthwise into two blocks, with one block fixed at a distance as a cortical shell and the second block particulated to fill the gap between graft and bone. Three stereolithographic (STL) files (pre-OP, full block, split block) were generated using an intraoral scanner. All STL files were evaluated for volume gain and horizontal bone dimensions.
Results: A mean volume gain of 0.36 cm2 (SD: 0.09) was achieved for the full block and 0.78 cm2 (SD: 0.14) for the split block using the same block. The difference was statistically significant (P < .0001). A mean horizontal bone gain of 4.37 mm (SD: 0.93) was achieved with a full block and 5.77 mm (SD: 0.85) with the shell technique (P < .0001).
Conclusion: With the same amount of bone removed, first as a full block and then as a split block, the split-block technique achieved a significantly higher bone gain compared with the full-block design.
Keywords: autogenous bone, bone augmentation, bone blocks, bone regeneration, graft design, intraoral bone graft
Pages 1090-1097, Language: English
Purpose: The aim of this study was to evaluate the effect of ultraviolet (UV) photofunctionalization on peri-implant osteogenesis of miniscrews.
Materials and Methods: Titanium orthodontic miniscrews were placed in the maxillary premolar-molar region of 17 patients undergoing fixed orthodontic treatment. This was a split-mouth study wherein the miniscrews on one side were treated with UV photofunctionalization and those on the other side were left untreated. Photofunctionalization was performed by placing the miniscrews in a chamber consisting of UV-A and UV-C lights for 15 minutes immediately prior to implantation. Efficacy of the UV chamber was assessed by examining stereomicroscopic images of a 10-μL droplet of double-distilled water placed on a UV-treated titanium pellet. Retrieved miniscrews were evaluated for bone-miniscrew contact (BMSC) using scanning electron microscopy (SEM) based on a custom-devised 4-point objective scoring system. Surface element deposition of miniscrews was estimated using energy-dispersive x-ray spectrometry (EDX). Ratios of Ca/Ti and Ca/P were calculated for upper, middle, and lower regions of all miniscrews.
Results: Increased spread of the water droplet over the UV-treated pellet showed that photofunctionalization converted the titanium surface from hydrophobic to superhydrophilic. SEM imaging revealed that BMSC was greater in the photofunctionalized group, but only in the lower third of miniscrews, and this was not statistically significant. EDX analysis revealed that Ca/Ti and Ca/P ratios in both groups were similar. Thus, there was no significant difference between peri-implant osteogenesis of UV-treated and untreated miniscrews.
Conclusion: These results suggest that UV photofunctionalization did not enhance the biologic potential of titanium orthodontic miniscrews in clinical application.
Keywords: miniscrews, osteogenesis, photofunctionalization, stability, superhydrophilic, ultraviolet
Pages 1099-1111, Language: English
PURPOSE: The purpose of this meta-analysis was to evaluate the short- and long-term outcomes for marginal bone level changes around implants that benefit from one of three commercially available implant surface preparations: Astra Tech OsseoSpeed (ATO), Straumann SLA/SLActive (SLA), and Nobel Biocare TiUnite (NBT).
MATERIALS AND METHODS: A MEDLINE (full text) search was conducted in July 2019 using the search terms "dental implant," "prospective," "bone level," and either implant surface/brand "TiUnite," "Nobel," "Nobel Biocare" (Nobel Biocare); or "OsseoSpeed," "Astra Tech" (Astra Tech); "Dentsply" or "SLA"; "SLActive" or "Straumann," in different combinations. Additionally, searches in Google Scholar, Elsevier, and Wiley publisher homepages were made. The abstracts were screened for eligibility, according to predefined inclusion and exclusion criteria. Initial screening resulted in 588, 813, and 616 publications for ATO, SLA, and NBT, respectively. The principal outcome measure was change in marginal bone levels at the 1- and 5-year follow-ups. A weighted mean value for the marginal bone level changes (MBLC(w)) based on the number of implants analyzed in each of the studies and a standard error mean for the MBLC(w) were calculated (SEM(w)). A test of the null hypotheses that the MBLC was equal in each pair of the three groups was carried out for all data available at the implant level, using both the Student t test and Wilcoxon rank sum test. A P value below 5% was considered statistically significant.
RESULTS: After a full-text analysis and screening, a total of 37 ATO, 23 SLA, and 53 NBT publications qualified for inclusion in the meta-analysis for both the 1- and 5-year data. At the 1-year follow-up, data were available for 2,586 implants for ATO, compared with 1,490 and 3,948 implants for SLA and NBT, respectively. A weighted analysis revealed that mean MBLC(w) was -0.29 mm (SEM(w): 0.0005 mm, SD: ± 0.42 mm) for ATO, compared with -0.83 mm (SEM(w): 0.0025 mm, SD: ± 0.36 mm) for SLA and -0.87 mm (SEM(w): 0.0006 mm, SD: ± 0.56 mm) for NBT. There was a statistically significant difference between ATO vs SLA (P < .0001), ATO vs NBT (P = .0012), and SLA vs NBT (P = .0488). Data at the 5-year follow-up were available for 1,168, 202, and 1,683 implants from the ATO, SLA, and NBT groups, respectively. Analysis revealed that mean MBLC(w) was -0.35 mm (SEM(w): 0.0038 mm, SD: ± 0.66 mm) for ATO compared with -0.74 mm (SEM(w): 0.0154 mm, SD: ± 0.45 mm) for SLA and -1.19 mm (SEM(w): 0.0107 mm, SD: ± 0.61 mm) for NBT. There was a statistically significant difference between ATO vs SLA (P = .0024) and ATO vs NBT (P = .0240). The difference between SLA and NBT did not reach statistical significance (P = .0769).
CONCLUSION: Based on the current meta-analysis, the null hypotheses could be rejected, and even if all groups demonstrated only a small mean amount of change in marginal bone levels at the 1- and 5-year follow-ups, there was a statistically significant difference between the three implant surface preparations, with the ATO surface showing superior marginal bone maintenance.
Keywords: dental implants, marginal bone level change, meta-analysis, OsseoSpeed, SLA, SLActive, TiUnite
Pages 1113-1121, Language: English
Purpose: To assess different microstructured surfaces created by sandblasting and acid etching in an effort to optimize the osseointegration performance of dental zirconia implants with an optimized surface.
Materials and Methods: Sixty CAD/CAM zirconia implants were divided into four groups. The control group had no surface treatment after sintering. The other groups had three different types of surface modifications: sandblasting; sandblasting and etching with hydrofluoric acid; and sandblasting and etching with an experimental hot etching solution composed of methanol, 37% hydrochloric acid, and ferric chloride, heated to 100°C and applied for 60 minutes. Commercially available titanium implants with sandblasted and etched surfaces and identical dimensions were employed as a positive control. Surface micromorphologies of implants from the five groups were evaluated. The osseointegration performance of all the implants was assessed in adult New Zealand rabbits based on microcomputed tomography (micro-CT) and histologic analysis.
Results: Sandblasting and acid etching with hot etching solution or hydrofluoric acid exhibited moderately rough surfaces with microstructures in both microscale and nanoscale. The sandblasting and etching with hydrofluoric acid group showed the highest surface roughness. Micro-CT revealed a significantly lower mean bone volume/total volume for the control group compared with the other four groups (P < .05). Among the groups, the sandblasting and hydrofluoric acid etching group was the highest, significantly higher than the titanium implant and sandblasting groups (P < .05). The sandblasting and etching with hot etching solution (P = .006) group also showed a significantly higher bone volume/total volume value than the titanium implant group. Histologic analysis revealed significantly higher boneto- implant contact for implants with modified surfaces compared with a sintered surface (P < .05), and no significant difference was found with respect to the sandblasted and etched titanium implants.
Conclusion: The microstructured surfaces created by sandblasting and acid etching show osseointegration comparable to that of commonly used titanium implants.
Keywords: dental implants, microstructure, osseointegration, surface topography, zirconia
Pages 1122-1131, Language: English
Purpose: The aim of this study was to evaluate and compare bone growth and implant integration in circumferential defects with two commercially available bone substitutes (demineralized bovine bone mineral [DBBM]).
Materials and Methods: Circumferential defects were created in the mandibles of minipigs (n = 10), and Bone Level Tapered implants (Straumann Roxolid with SLActive surface) were placed. The defects (4-mm-deep circumferential defect, 2 mm around each implant) were augmented with either sintered bovine bone mineral (test, cerabone) or natural bovine bone mineral (control, Bio-Oss). Bone formation and tissue composition in augmented sites were histomorphometrically assessed after 8 and 12 weeks of healing time (n = 5 each), respectively, in terms of the percentage of area of newly formed bone to total area, bone-to-implant contact (BIC), and crestal bone height relative to the implant shoulder (first bone-to-implant contact [fBIC]).
Results: Bone formation in all defect sites was adequate and equivalent for both groups at individual healing time points. The amount of residual graft material was comparable in both groups after 8 and 12 weeks, with no significant resorption in either group. The mean newly formed bone area in the test group amounted to 46.7% ± 5.1% and 48.7% ± 4.0% after 8 and 12 weeks vs 47.0% ± 4.8% and 47.8% ± 7.3% in the control group, respectively. BIC and fBIC as individually assessed for the lingual and buccal aspects were comparable at both healing time points without any statistically significant differences between the groups. A slightly greater variability of fBIC was observed within the test group.
Conclusion: The results of this study indicate that test and control materials both represent viable bovine bone graft material that equivalently support the formation of new and stable bone volume specifically when used for simultaneous augmentation around implants.
Keywords: Bio-Oss, bone formation, bone-to-implant contact, cerabone, circumferential defect, demineralized bovine bone
Pages 1132-1140, Language: English
Purpose: To evaluate and compare the effects of two restorative materials with different stiffness on peri-implant bone microstrain and implant micromovements during occlusal loading in implant-supported single and adjacent splinted crowns.
Materials and Methods: Two 3 × 10-mm implants were inserted into the tibia of four rabbits. During the osseointegration process, prosthetic restorations were performed. Before suturing the flap, each implant’s position and direction were obtained by fastening two splinted transfer abutments, onto which implant analogs were placed and fastened; the splinted transfer abutments were subsequently unfastened. Splinted transfer abutment/analog complexes were cast using type IV plaster to obtain eight different working models. Two single mandibular premolar crowns of monolithic zirconia and acrylate polymer composite were generated using CAD/CAM technology, and 16 adjacent splinted crowns (eight of each material) with the same design were also generated. After 6 weeks of implant osseointegration, the animals were sacrificed. Tibial sections with the implants were extracted, and prosthetic restorations (performed during implant osseointegration) were fastened to the implants. Static loading tests were performed with 100-N force application and an inclination of 6 degrees over the central fossa of the premolars. Implant micromovement was measured using an image analysis technique. Bone microstrain was quantified using two strain gauges placed on the crestal bone around the implants. Data were analyzed using two-way analysis of variance.
Results: The mean implant micromovement values were lower for monolithic zirconia single and splinted crowns (61.5 ± 26.3 μm and 57.7 ± 8.8 μm, respectively) than for acrylate polymer composite-based single and splinted crowns (78.9 ± 37.3 μm and 59.61 ± 11.5 μm, respectively). No significant differences between the materials were noted. Bone microstrain around the implants was lower for splinted crowns (303.7 ± 281.3 με for acrylate polymer composite; 312.4 ± 226.8 με for monolithic zirconia) than for single crowns (539.7 ± 8.8 με for acrylate polymer composite; 574.6 ± 271.9 με for monolithic zirconia).
Conclusion: Using restorative materials of different stiffness did not significantly affect the micromovement of already-osseointegrated implants supporting single or splinted crowns. Independent of material stiffness, single crowns transfer significantly more microstrain than splinted crowns.
Keywords: acrylate polymer, dental implants, dental prosthesis, implant-supported, zirconia
Pages 1141-1148, Language: English
Purpose: The purpose of this study was to determine the minimum torque required to attach the transducer to the implant to measure the implant stability quotient (ISQ) with two different devices and to estimate if finger-generated torque would be reliable for this purpose.
Materials and Methods: One hundred implants were inserted into a uniform polyurethane block. The implants were distributed into 10 groups, with 10 implants each. The transducers were manually attached by a female operator (G female) and by a male operator (G male) using the standard connector provided by the manufacturers. For the remaining groups, the transducers were placed using a connector adapted to a digital torque wrench with different torque settings: 3 Ncm (G 3Ncm), 4 Ncm (G 4Ncm), 5 Ncm (G 5Ncm), 6 Ncm (G 6Ncm), 10 Ncm (G 10Ncm), 13 Ncm (G 13Ncm), 17 Ncm (G 17Ncm), and 20 Ncm (G 20Ncm). The stability was measured for all groups using both the Osstell and the Penguin resonance frequency analyzers. The minimum, medium, and maximum finger grip torque were accessed on 100 volunteers.
Results: For Osstell, the conjugated confidence intervals were homogenous for four groups (G 10Ncm, G 13Ncm, G 17Ncm, and G 20Ncm), and for Penguin, they were homogenous for six groups (G 5Ncm, G 6Ncm, G 10Ncm, G 13Ncm, G 17Ncm, and G 20Ncm). The minimum finger-generated force was 2.18 ± 1.05 Ncm, the medium force was 4.25 ± 1.57 Ncm, and the maximum force was 7.51 ± 2.52 Ncm, measuring with a digital torque meter.
Conclusion: For an accurate measurement of ISQ, the minimum torque necessary to insert the transducer into the implant for Osstell was 10 Ncm, while for Penguin, it was 5 Ncm. Therefore, when using Osstell to assess implant stability, the authors suggest the use of a torque wrench to ensure 10 Ncm of force is applied when tightening the transducer into the implant to obtain accurate stability measurements. When using Penguin, the maximum finger-generated tightening force is enough.
Keywords: dental implants, implant stability quotient, in vitro technique, primary implant stability, resonance frequency analysis, transducer
Pages 1149-1158, Language: English
Purpose: This systematic review aimed to assess the effect of chlorhexidine (CHX) in preventing complications after extractive, implant, and periodontal surgery.
Materials and Methods: The PICO question set for this systematic review was: “Is the use of chlorhexidine formulations able to prevent complications (safety) in patients undergoing procedures of either oral surgery, dental implantology, or periodontology compared to treatment procedures in patients without a chlorhexidine prescription?” Once inclusion and exclusion criteria were established, a search was carried out independently by two researchers on PubMed/MEDLINE, Scopus, and Web of Science. The primary outcomes investigated were the rate of alveolar osteitis and bacteremia after surgical procedures in oral surgery. Meta-analysis and trial sequential analysis (TSA) were performed in order to evaluate the findings.
Results: After the selection, the 32 studies that fully met the eligibility criteria were considered in this systematic review. A meta-analysis was only possible for data obtained from studies related to extractive surgery. Meta-analysis and TSA showed a statistically significant decrease in the rate of alveolar osteitis after tooth extraction when CHX was employed compared with placebo treatments or treatments not using CHX (RR = 0.49; 95% CI: [0.40, 0.60], P < .001; I2 = 8%). Focusing on the rate of bacteremia, meta-analysis and TSA showed how the employment of CHX (RR = 0.87; 95% CI: [0.79, 0.96], P = .004; I2 = 4%) decreases the rate of bacteremia after extractive surgery. Data from the literature seem to lack in the evaluation of CHX use for the reduction of complications in periodontology and implant dentistry.
Conclusion: This systematic review showed with a good power of evidence that CHX employment reduces alveolar osteitis and bacteremia rates after dental extractions.
Keywords: chlorhexidine, complication, efficacy, prevention, systematic review, TSA
Pages 1159-1169a, Language: English
Purpose: To compare the accuracy of different modalities of implant placement—static fully guided, static half-guided, and freehand surgery—through meta-analysis.
Materials and Methods: A thorough electronic and manual systematic search was conducted to identify applicable randomized clinical trials (RCTs) for evaluating the implant positioning accuracy between different static implant navigation surgeries. The coronal and apical horizontal deviation, vertical deviation, apical angle, and chair time were estimated as the weighted mean differences and standard deviation with confidence intervals. A P value of .05 was set for statistical significance.
Results: Based on the 10 RCTs that met the inclusion criteria for the quantitative analyses, results from the meta-analyses demonstrated the following: (1) a coronal deviation significant difference favoring the fully guided approach compared with the half-guided (weighted mean difference of –0.51 mm) and freehand approaches (weighted mean difference of –1.18 mm); (2) a significant weighted mean difference between the fully guided and half-guided approaches in relation to the apical deviation (weighted mean difference of –0.75 mm); (3) the vertical comparison did not yield significant weighted mean differences between the fully guided and half-guided techniques (–0.23 mm) and lacked statistically significant difference between the fully guided and freehand techniques (weighted mean difference of –0.17 mm); (4) the apical angle deviation demonstrated a significant weighted mean difference in favor of the fully guided approach compared with the half-guided group (weighted mean difference of –3.63 degrees); and (5) the comparison of chair time between the investigated groups did not exhibit a significant difference in any of the techniques.
Conclusion: Static fully guided implant navigation surgery has the highest accuracy for transmitting the presurgical positioning planning to the patient, followed by static half-guided surgery, while the freehand implant placement provides the least accuracy.
Keywords: accuracy, computer-aided surgery, computer-assisted, meta-analysis, systematic review
Pages 1170-1176, Language: English
Purpose: Premature loss of a tooth element causes extensive local bone atrophy. Block biomaterials are used in patients with an atrophic maxilla to reshape the premaxilla bone. This study aimed to evaluate the responses to xenogeneic bone blocks at cellular and tissue levels.
Materials and Methods: Viability of human periodontal ligament stem cells (hPDLSCs) submitted to culture medium–containing substances leached from a xenogeneic block biomaterial (Orthogen) was assessed by the MTT assay. Cells grown in a fresh medium were used as the control. Cell viability was measured at 24, 48, and 72 hours. The results were statistically compared (α ≤ .05). Tissue response to the biomaterial was evaluated by the placement of xenogeneic blocks anchored with miniscrews in six patients with atrophic maxillae and a remaining cortical bone tissue thickness of 2.0 to 3.0 mm. After 8 months, specimens were collected from the grafted areas and analyzed under a light microscope for evaluating the types of collagen fibers and amount of newly formed bone tissue, using the Image-Pro Plus software program.
Results: The number of viable cells was similar in both groups. The histologic sections revealed remaining biomaterial in 10.12% of the patients and newly formed bone in 21.57%.
Conclusion: The xenogeneic block biomaterial tested proved to be biocompatible in vitro, and the porosity of the block favored the in vivo formation of new bone matrix deposits.
Keywords: block biomaterials, bone atrophies, cell viability, histology, periodontal ligament stem cells, xenogeneic graft
Pages 1177-1186, Language: English
Purpose: To carry out a retrospective analysis of the placement of zygomatic implants in atrophic maxillae and to assess the outcomes in terms of survival rate and biologic complication incidence, with a follow-up of at least 1 year and in 13% of cases, longer than 5 years.
Materials and Methods: The study included all patients rehabilitated through zygomatic implant surgery from 2006 to 2017 and excluded those treated in 2018 to guarantee a minimum follow-up of 1 year. Depending on the specific case, one, two, or three zygomatic implants were placed in combination with conventional implants, or four zygomatic implants were placed alone (zygoma quad). All implants were placed by the same surgeon in a private clinic through an anatomy-guided surgical approach and were immediately loaded with screwed provisional prostheses up to the end of the osseointegration phase. Patients who did not undergo any or the last follow-up visits were not included in order to assess the real conditions of implants, soft tissues, and maxillary sinuses in the last year of follow-up (2018).
Results: A total of 206 zygomatic implants were placed in 102 patients. There were only two failures due to a lack of osseointegration (0.97%): in one case, 3 months after placement and in the other one, 2 years after placement. There were five cases of sinusitis (2.42%), two of which also presented oroantral communication (0.97%); in three cases, antibiotic and conservative treatments alone were not effective, so the removal of the zygomatic implant was necessary. Finally, two cases of mucosal recession (0.97%) appeared in two anterior zygomatic implants. The global survival rate was 97.57%, and all biologic complications are currently stable.
Conclusion: In this study, the rehabilitation of atrophic maxillae through zygomatic implants was shown to be a predictable treatment, which allows a graftless approach and makes it possible to carry out immediate loading protocols, with enormous psychologic advantages for patients. Survival rates are high, and complication incidence is low. Thus, at present, zygomatic implants may be considered a reliable treatment option in the case of severe atrophic maxillae.
Keywords: atrophic maxilla, complications, immediate loading, survival rate, zygomatic implants
Pages 1187-1194, Language: English
Purpose: Dental implant treatment is one of the most successful methods to replace lost teeth. However, several factors play a role in the early failure of implants, which could occur prior to the insertion of the restorative component. This study aimed to investigate the rate of early implant failure in the maxillary posterior area with and without sinus augmentation and other related risk factors.
Materials and Methods: Data were collected from the records of patients who received implant treatment in the posterior maxilla (premolars and molars). The information included whether the sinus was augmented or not, method of augmentation, sex, age, smoking, and medical history. In addition, length and diameter of the implant, whether the sinus membrane was perforated or not, implant sites, patients who received implants both with and without sinus augmentation, and manufacturers of the implants were also recorded.
Results: A total of 1,343 patients who received 2,323 implants were included with a failure rate equal to 4.4%. Logistic regression showed that failure rate was significantly associated with smoking (odds ratio [OR]: 7.843), diabetes (OR: 3.190), older age groups (OR: 1.027), and long implants (OR: 1.177). Failure rate significantly decreased with the lateral augmentation procedure (OR: 0.345).
Conclusion: The results suggested that the lateral augmentation procedure was negatively associated with failure rate. Yet, old age, smoking, diabetes, and longer implants showed a positive association with the increased rate.
Keywords: implant, implant survival, sinus augmentation, survival rate
Pages 1195-1202, Language: English
Purpose: This retrospective study compared the long-term outcomes of dental implants according to type of connection and surface.
Materials and Methods: Multiunit restorations were classified as follows: an external connection with a turned surface, an external connection with an anodized surface, or an internal connection with a fluoride-modified surface. Patients who were followed up for longer than 7 years after implant loading were included in the study. Cumulative implant survival rates and the amounts of marginal bone loss were calculated by reviewing dental records and radiographs. Only implants that survived until the last follow-up visit were included in the analysis of marginal bone loss. Statistical analyses were performed to detect between-group differences at the significance level of .05.
Results: Sixty-nine patients with 261 bone-level implants were included. The average follow-up duration was 15.2 years in the external turned group, 10.6 years in the external anodized group, and 9.9 years in the internal fluoride-modified group. There was no significant between-group difference in the cumulative survival rate (P = .439) despite eight implant failures (six in the external turned group and two in the internal fluoride-modified group). The mean (SD) marginal bone loss values at the last follow-up were 0.47 mm (0.67), 0.87 mm (1.07), and 0.23 mm (0.58) in the external turned, external anodized, and internal fluoride-modified groups, respectively. After adjusting for follow-up duration, there was significantly less marginal bone loss in the external turned group than in the external anodized group (P < .001) and in the internal fluoride-modified group than in the external anodized group (P < .001). No significant difference in marginal bone loss was found between the external turned and internal fluoride-modified groups (P = .44).
Conclusion: The implant-abutment connection structure is an important contributor to the maintenance of the level of marginal bone surrounding the implant. Implant surface characteristics are another contributor to marginal bone resorption.
Keywords: bone resorption, dental implant-abutment design, dental implants, retrospective studies, surface properties
Pages 1203-1208, Language: English
Sinus floor elevation with the lateral window approach has proven to be an effective treatment modality for vertical bone augmentation in the posterior region of the maxilla. The simultaneous implant placement during the procedure can be achieved if enough remaining bone height is available to obtain implant primary stability. However, the proper identification of the maxillary sinus boundaries for the window demarcation along with membrane protection for simultaneous implant placement can be challenging. This clinical report demonstrates a novel technique for sinus floor augmentation using a 3D modified implant-osseous-membrane surgical template to assist in the lateral window demarcation, membrane stabilization and protection, and guided implant placement in a partially edentulous patient who was eligible for one-stage sinus floor elevation. The surgical procedure for the sinus demarcation is simplified, the membrane stabilization and protection are effective, and the guided implant placement provided a predictable surgical positioning of the implants.
Keywords: CAD/CAM, guided implant surgery, guided sinus floor elevation, sinus floor elevation, 3D printing
Pages 1209-1217, Language: English
Purpose: The aim of this study was to inspect the mechanical fatigue behavior of an implant-supported restorative system using polyether ether ketone (PEEK) and yttria partially stabilized zirconia polycrystals (YZ) as materials for customized definitive implant-supported hybrid abutments, supporting two types of all-ceramic restorations: translucent zirconia (TZ) and lithium disilicate (LD) monolithic crowns.
Materials and Methods: Forty Morse taper implants were included in epoxy resin. Titanium intermediary abutments were placed, and the specimens were randomly allocated into four groups (n = 10) according to the customized hybrid abutment material (PEEK or YZ) and the monolithic crowns (TZ or LD) representing a maxillary central incisor crown. The specimens were subjected to a mechanical fatigue test (step-stress analysis) by means of an initial 200-N load for 5,000 cycles and subsequent increase of 50 N (step-size) at each 10,000 cycles, until failure occurred. The load at failure and number of cycles until failure were recorded; survival probabilities and specimen displacement were calculated for each step. The failure pattern was evaluated, and the Weibull modulus was obtained for each condition.
Results: Fatigue of both types of crowns was not influenced by the abutment material (LD-PEEK = LD-YZ; TZ-PEEK = TZ-YZ). In the PEEK abutment, the values obtained in the LD and TZ crowns showed no statistical difference; however, in the YZ abutment, the TZ crown presented a load at failure value that was statistically higher than that for LD. Failure pattern analysis revealed a higher prevalence of crown fracture for LD groups, while screw/implant platform fractures were shown for TZ groups.
Conclusion: YZ and PEEK hybrid abutments promoted similar fatigue levels regardless of the crown materials, TZ crowns promoted a higher fatigue level than LD ones when associated with YZ abutments, and LD crowns promoted a similar fatigue level to TZ ones when associated with PEEK custom abutments. Higher prevalence of crown fractures was shown for LD and screw/implant platform fractures for TZ groups.
Keywords: dental implants, lithium disilicate, mechanical cycling, single crowns, yttria-stabilized tetragonal zirconia, zirconium oxide
Pages 1218-1228, Language: English
Purpose: The purpose of this prospective clinical study was to evaluate the efficiency of alveolar ridge reconstruction with the lateral border of scapula (LBS) prior to implant placement and to assess onlay graft retention and bone resorption during a short term of function.
Materials and Methods: A total of 25 partially or fully edentulous patients with severe alveolar bone atrophy received ridge reconstruction with grafts harvested from the LBS. Histologic analysis of bone grafts was performed. Six months after augmentation, patients underwent CBCT and received dental implants. After another 3 months, healing abutments and implant-supported dentures were placed. Patients were followed for an average of 24 months.
Results: Thirteen patients received primary bone grafting from LBS. Twelve patients experienced unsuccessful ridge reconstruction with other grafts before and were secondarily augmented with LBS. The average dimensions of LBS grafts were 6.3 × 2.3 × 1.2 cm. Histologic analysis confirmed the cortical nature of the graft. No donor-site complications occurred, and arm movements were restored within 2 weeks. Following augmentation, two patients had sutures disrupted that healed uneventfully after revision. The average resorption of LBS grafts after 6 months was 12.2% ± 3.0%. At the time of implant placement, the dimension of the ridge was 12.3 ± 2.0 mm and 6.9 ± 1.6 mm in height and width, respectively. The survival rate of the 174 implants placed was 98.3%.
Conclusion: LBS can be used as an alternative extraoral grafting site for extensive ridge reconstruction prior to implant placement.
Keywords: autologous bone grafts, lateral border of scapula, ridge reconstruction, severe bone atrophy
Pages 1229-1238, Language: English
Purpose: Narrow dental implants are commonly used to restore narrow alveolar ridges. Although the good performance of narrow dental implants supporting multiple prostheses has been repeatedly demonstrated, there are few studies analyzing their performance in a long-term follow-up together with the influence of the loading protocol. Thus, the objective was to assess the influence of implant loading protocol (immediate vs delayed) on the long-term outcomes of 3.0-mm-diameter dental implants supporting fixed multiple prostheses.
Materials and Methods: This retrospective cohort study included 202 3.0-mm-diameter dental implants supporting multiple prostheses placed between January 2006 and April 2009. Immediate loading was performed when the implants were inserted in bone types I, II, and III and achieved an insertion torque ≥ 25 Ncm; otherwise, delayed loading was performed. The survival of the dental implants was recorded together with clinical and demographic information of the participants. The prosthetic complications (ceramic chipping, screw loosening, screw fracture, decementation, prosthesis failure) were also recorded. The marginal bone loss since insertion and the marginal bone loss since loading were calculated.
Results: Delayed implant loading was performed in 131 implants and immediate loading in 71 implants. The follow-up time was 106 ± 40 months and 117 ± 38 months in the delayed and immediately loaded implants, respectively. The implant loading protocol (delayed vs immediate) showed no influence on the implant survival rate (96.2% vs 97.2%) and the marginal bone loss since insertion (1.2 ± 1.0 mm vs 1.2 ± 1.0 mm).
Conclusion: The implant loading protocol (immediate vs delayed) did not influence the long-term outcomes (survival and marginal bone loss) of 3.0-mm-diameter dental implants supporting fixed multiple prostheses. These results are in favor of considering immediately loaded narrow dental implants as a viable treatment alternative for horizontally resorbed ridges. Nevertheless, future randomized clinical trials are needed to confirm these observations.
Keywords: bone atrophy, immediate loading, implantology, long-term survival, narrow dental implants
Pages 1239-1247, Language: English
Purpose: Advances in surface technology and the understanding of the capabilities of osseointegrating implants have led to the use of shorter implants in a variety of clinical situations. Such implant use offers a number of potential advantages in the posterior maxilla and mandible. The purpose of this retrospective study was to examine the success rates of shorter, tissue-level implants in function for at least 60 months.
Materials and Methods: A retrospective study was conducted of all patients treated between January 1, 1998, and December 31, 2012, who received tissue-level endosseous implants 8 mm or less in length, which were restored with abutments and single crowns. Patient age, sex, location of implants, and diameter of implants were examined. Time in function and stability of peri-implant crestal bone were assessed.
Results: The retrospective analysis identified 4,251 tissue-level implants that were restored with single abutments and crowns. These implants were followed for up to 228 months in function, with a mean time in function of 127.2 months. Implant success was assessed using commonly utilized metrics combined with bone sounding on the midbuccal and midlingual/ palatal aspects of the implants. The cumulative success rate was 99.5% for all implants. In the posterior mandible, the success rate for regular-neck implants was 99.3% (n = 680, mean time in function: 136.5 months) and was 99.7% for wideneck implants (n = 2,320, mean time in function: 124.5 months). In the posterior maxilla, the success rate for regular-neck implants was 97.8% (n = 211, mean time in function: 169.1 months), and for wide-neck implants, it was 99.2% (n = 1,040, mean time in function: 127.8 months).
Conclusion: The use of shorter (8 mm or less in length) tissue-level implants in the maxilla and mandible, restored with single abutments and crowns, offers a viable treatment option, assuming specific criteria and protocols are followed. These criteria and protocols are discussed.
Keywords: implant success, osseointegrating implants, short implants
Pages 1248-1256, Language: English
Purpose: To evaluate the 5-year results of the clinical and radiographic outcomes of three types of early loaded implants.
Materials and Methods: Seventy-five implants were placed in the posterior mandible or maxilla in 30 patients. Three types of implants (Straumann SLActive, Astra OsseoSpeed, and Thommen Implant System) were used. Definitive restorations were made after 8 weeks of implant placement. The radiographs were taken at the placement of the prosthesis, at 6 months, and at 1- and 5-year follow-ups. Clinical and radiologic data were evaluated for all types of implants. The Wilcoxon signed rank test, least significant differences, and Mann-Whitney U were used to test for statistically significant differences (P < .005).
Results: Twenty-four patients and 62 implants were evaluated after 5 years. The mean marginal bone loss was 0.20 ± 0.40 mm, 0.21 ± 0.05 mm, and 0.25 ± 0.36 mm after 1 year and 0.32 ± 0.22 mm, 0.31 ± 0.26 mm, and 0.42 ± 0.36 mm after 5 years for the Straumann, Astra, and Thommen groups, respectively. After 5 years, the mean peri-implant probing depth level was 1.75 ± 0.49 mm, 1.87 ± 0.48 mm, and 1.92 ± 0.57 mm for the Straumann, Astra, and Thommen groups, respectively. No peri-implantitis was detected after 5 years of loading.
Conclusion: All groups of implants showed a stable peri-implant probing depth and marginal bone level. The survival rate was high and bone loss was low at 5 years; thus, early loading may be a useful procedure that allows reduction in treatment time.
Keywords: early loading, implant stability, marginal bone loss
Online OnlyPages 91-97, Language: English
Purpose: Placement of dental implants adjacent to teeth with inflammation, such as periapical lesions, may have implications on the implant prognosis. The aim of this study was to systematically collect the available evidence regarding the influence of endodontic status of adjacent teeth on dental implant prognosis.
Materials and Methods: A systematic electronic search was conducted using the MEDLINE (PubMed), Embase, EBSCO, CINHAL, COCHRANE, and SCOPUS databases in August 2019. The search was further supplemented with a hand-search citation mining process. All types of studies that addressed the endodontic condition of the adjacent tooth and evaluated dental implant success or survival were analyzed and evaluated according to the PRISMA and NOS guidelines.
Results: Overall, seven human studies were included in the final analysis. Those included a total of 1,914 implants placed adjacent to teeth with periapical lesions or root canal treatments. Four studies included implants placed adjacent to teeth with periapical lesions (1,634 implants), and three studies included implants placed adjacent to teeth with root canal treatments (280 implants). Lower success rates of dental implants placed adjacent to teeth with periapical lesions or to endodontically treated teeth were reported; however, the results were inconsistent.
Conclusion: There is some evidence to support an association between the endodontic condition of the adjacent tooth and the success of dental implants, but it is not enough to support a causative relationship. Nevertheless, clinicians should treat any active sources of infection and inflammation in adjacent teeth prior to insertion of dental implants.
Keywords: bacteria, bone loss, complications, inflammation, prognosis, survival
Online OnlyPages 99-108, Language: English
PURPOSE: To investigate the odds of developing open proximal contact (OPC) between implant-supported fixed prostheses and adjacent teeth compared with that between tooth-supported fixed prostheses and adjacent teeth.
MATERIALS AND METHODS: A search was conducted in the Ovid MEDLINE, Embase, and Web of Science databases for clinical studies on OPC developed with implant-supported prostheses or tooth-supported prostheses. A meta-analysis was performed using statistical software to estimate the odds of developing OPC with implant-supported prostheses compared with tooth-supported prostheses, with a 95% confidence interval (CI). The statistical significance was defined as P < .05.
RESULTS: The odds ratio (OR) of developing OPC with implant-supported prostheses was 2.46 compared with tooth-supported prostheses (95% CI [1.21 to 5.01]; P = .013]. However, the data were highly heterogenous (τ(2) = 0.40, I(2) = 95.67%). The total estimates of developing OPC were 41% (95% CI [30% to 54%]) with implant-supported prostheses and 22% (95% CI [18% to 26%]) with tooth-supported prostheses. OPC was more prevalent at the mesial side than at the distal side of implant-supported prostheses (OR = 2.38, 95% CI [0.94 to 6]; P = .066), whereas OPC was more prevalent at the distal side than at the mesial side of tooth-supported prostheses (OR = 1.94, 95% CI [1.09 to 3.45]; P = .024). There was no statistically significant difference in developing OPC with covariates of sex, age, arch, splinting of implants or adjacent teeth, region, and vitality of adjacent teeth, retention type, opposing dentition, occlusal force, parafunctional activities, and follow-up time. OPC was found to increase 9% per year with implant-supported prostheses (OR = 1.09). The estimate of interproximal gap next to implant-supported prostheses was 245.8 μm (95% CI [86.4 to 405.3 μm]).
CONCLUSION: Within the limitations of this systematic review and meta-analysis, the odds of developing OPC were significantly higher with implant-supported prostheses than with tooth-supported prostheses. However, the data were highly heterogenous, and thus, a well-designed randomized clinical study needs to be conducted to validate the results of this systematic review.
Keywords: growth, implant-supported fixed prosthesis, interproximal gap, occlusal force, open proximal contact, toothsupported fixed prosthesis