Pages 241-242, Language: English
Pages 244-247, Language: English
DOI: 10.11607/jomi.7811, PubMed ID (PMID): 32142560Pages 249-256, Language: English
Purpose: Raloxifene, an antiresorptive drug, prevents bone loss and promotes bone formation by secondary anabolic action. The purpose of this study was to investigate the effectiveness of raloxifene on the osseointegration of implants in the rat model of the osteoporotic maxilla.
Materials and Methods: Thirty Sprague-Dawley female rats aged 10 weeks were randomly assigned to the following groups: (1) raloxifene (RAL) group (n = 10), (2) ovariectomized (OVX) group (n = 10), and (3) control group (sham-operated, n = 10). Both ovaries were removed to induce osteoporosis, and the maxillary right molar was extracted. After 4 weeks, an implant was placed on the same edentulous area. Raloxifene 1 mg/kg/day was administered to the experimental animals in the RAL group, while those in the ovariectomized group and sham-operated group were given the same amount. All experimental animals were sacrificed at 4 weeks after implants were placed. Histomorphometric measurements of the bone area ratio (BA, %) and bone-to-implant contact ratio (BIC, %) around the implant were performed. Three-dimensional (3D) microcomputed tomographic (micro-CT) analysis of peri-implant bone microarchitecture was also performed and statistically analyzed.
Results: In the histomorphometric analysis, the BA ratio of the implant in the RAL group was higher than that in the OVX group (53.3% ± 7.2% vs 38.2% ± 11.7%, P = .024). BIC around the implant in the RAL group did not show a statistical difference compared with that in the OVX group (42.7% ± 15.0% vs 34.5% ± 16.2%, P > .05). In microstructural analysis, the RAL group showed a significant increase of trabecular thickness compared with the OVX group (0.09 ± 0.02 mm vs 0.06 ± 0.01 mm, P = .013). However, raloxifene did not show convincing differences between the groups in other micro-CT parameters (P > .05).
Conclusion: The results show that raloxifene administration demonstrated enhanced new peri-implant bone formation in the osteoporotic rat maxilla. Further research is needed to reveal the effect of raloxifene on the clinical outcome of patients with poor bone quality who undergo dental implant treatment.
Keywords: histomorphometric analysis, implant, osteoporosis, raloxifene, 3D micro-CT
DOI: 10.11607/jomi.7760, PubMed ID (PMID): 32142561Pages 257-264, Language: English
Purpose: The aim of this study was to evaluate the effect of implant designs with different lengths and diameters on the stress distribution in abutments, implants, and cortical and trabecular bone of the edentulous mandible via three-dimensional finite element analysis.
Materials and Methods: Eight different finite models (cylindrical 3.5 × 6; cylindrical 3.5 × 10.5; cylindrical 4.5 × 6; cylindrical 4.5 × 10.5; triple cylindrical 3.5 × 6; triple cylindrical 3.5 × 10.5; triple cylindrical 4.5 × 6; and triple cylindrical 4.5 × 10.5) were created. Abutments, abutment screws, and metal-retained porcelain crowns were modeled on the implants. A 200-N oblique load was applied on the buccal cusp of the crown. The highest maximum principal (Pmax) and minimum principal (Pmin) stresses were calculated for trabecular and cortical bone, and von Mises stress values were calculated for the implant and abutment.
Results: The triple cylindrical implant abutments showed lower stress values than cylindrical implant abutments. The highest von Mises stress values were observed in the cervical third of the abutments. The stress values on implants were found at the neck of the implants, and cylindrical implants showed higher stress values than triple cylindrical implants. The peak Pmax and Pmin values in cortical bone were detected around the implant neck. For implants with a 3.5-mm diameter, the triple cylindrical implant design showed lower stresses in cortical bone than the cylindrical implant design; however, similar stresses were observed in 4.5-mm implants for both designs. Implant length did not affect the stresses in cortical bone. Implants with a 10.5-mm length showed lower Pmax values than implants with a 6-mm length in trabecular bone. For Pmin values in trabecular bone, the triple cylindrical implant design had lower values than did the cylindrical implant design.
Conclusion: Within the limitations of this study, the triple cylindrical implants, with a new implant design, showed appropriate results in terms of abutment, implant, and bone tissue stress.
Keywords: dental implants, finite element analysis, implant design, stress distribution
DOI: 10.11607/jomi.7742, PubMed ID (PMID): 32142562Pages 265-274, Language: English
Purpose: Peri-implantitis is an important biologic complication that can lead to implant failure. Proper treatment should effectively kill bacteria, not harm the implant surface, and promote regeneration. Recently, photocatalytic coating without antibiotics or external agents was proposed to be an alternative to antibiotic therapy. The aim of this study was to evaluate the photocatalytic antibacterial effect of a new titanium implant coating made from hydroxyapatite-tryptophan complex and gray titania, which was activated by two visible lights.
Materials and Methods: Titanium alloy substrate was plasma sprayed with hydroxyapatite (80 wt%) and dititanium trioxide (20 wt%) and then pressed with tryptophan. Three bacteria related to peri-implantitis, Porphyromonas gingivalis, Tannerella forsythia, and Aggregatibacter actinomycetemcomitans, were used in this study. Six conditions were tested: (1) control group (only bacteria), (2) photocatalytic sample in darkness (bacteria and coated sample in darkness), (3) red laser for 15 minutes (bacteria irradiated with photoactivated disinfection [PAD] light, 650-nm wavelength), (4) broadband light-emitting diode (LED) for 15 minutes (bacteria irradiated with broadband LED, peak wavelength at 470 nm), (5) photocatalysis by red laser for 15 minutes (bacteria and coated sample irradiated with PAD light), and (6) photocatalysis by broadband LED for 15 minutes (bacteria and coated sample irradiated with broadband LED). After 15 minutes of irradiation, photocatalytic antibacterial effects were evaluated by total viable bacterial count, adenosine triphosphate (ATP) assay, and LIVE/DEAD assay.
Results: The number of all bacteria tested was significantly decreased by the photocatalytic effect of both visible light sources (P < .05). For P gingivalis, viable bacteria of lethal photosensitization groups were also significantly decreased (P < .05), especially when using the broadband LED. However, the coating material itself did not have antibacterial properties without light activation. There was no significant difference in ATP among groups (P > .05). LIVE/DEAD staining showed that red fluorescent bacterial cells were present in photocatalytic groups from the two light sources.
Conclusion: Photoactivated hydroxyapatite-tryptophan complex and gray titania as a photocatalytic coating has antibacterial effects on bacteria associated with periimplantitis.
Keywords: antibacterial, gray titania, hydroxyapatite, implant coating, photocatalytic, peri-implantitis
DOI: 10.11607/jomi.7913, PubMed ID (PMID): 32142563Pages 275-280, Language: English
Purpose: Platelet concentrates are used for regenerative periodontal and implant therapy. Up to now, no study has reported the influence of smoking on platelet-rich fibrin membranes. Hence, this crosssectional in vitro study aimed to analyze the influence of cigarette smoking on platelet morphology and fiber characteristics of both leukocyte- and platelet-rich fibrin and advanced platelet-rich fibrin membranes.
Materials and Methods: Sixty blood samples from both smokers (n = 34) and nonsmokers (n = 26) based on power analysis were collected and subjected for complete blood count and platelet morphology indices (mean platelet volume, platelet distribution width, platelet–large cell ratio, and plateletcrit). Leukocyte- and platelet-rich fibrin membrane (2,700 revolutions per minute for 12 minutes) and advanced platelet-rich fibrin membrane (1,500 revolutions per minute for 14 minutes) were prepared using a standard protocol. Thirtytwo platelet-rich fibrin membranes from 16 individuals were selected randomly from the two groups and were subjected to morphologic examination using a scanning electron microscope.
Results: Both of the groups were matched for age. Red cell counts and white cell counts showed no statistical difference between the groups. Platelet indices of smokers did show slightly higher values than the nonsmoking group. Scanning electron microscopic analysis showed variations in the fiber width and pattern among smokers in both the leukocyte- and platelet-rich fibrin and advanced platelet-rich fibrin membranes. Platelet cell morphology of the smoking group demonstrated spiky architecture, suggesting an active state, while in the nonsmoking group, the platelet cells were seen in clusters, suggesting a resting state.
Conclusion: Scanning electron microscopic results show that long-term cigarette smoking does affect the thickness and arrangement of fiber architecture in both leukocyte- and platelet-rich fibrin and advanced platelet-rich fibrin membranes and also could have an impact on activation of platelets.
Keywords: fibrin networks, growth factor, in vitro study, morphology, platelet-rich fibrin, platelets, smoking
DOI: 10.11607/jomi.7673, PubMed ID (PMID): 32142564Pages 281-288, Language: English
Purpose: The purpose of this study was to investigate the resistance against rotation of a two-piece abutment with or without the presence of a positioning hex in tapered internal connection implant systems.
Materials and Methods: A tapered internal connection implant with an 11-degree internal oblique angle was placed into a constructed three-dimensional (3D) bone model. Two types of abutments were compared: hex-type abutments with a positioning hex and two-piece round-type nonhex abutments. Vertical compressions equivalent to the screw tightening torque of 30 Ncm and 40 Ncm were applied to the abutment screws. A horizontal load of 150 N was applied to the superstructure to create moments. The contact area between the implant and abutment was compared and analyzed. The rotational displacement of the abutments was investigated as well.
Results: When a preload equivalent to 40 Ncm of tightening torque was applied, the round-type abutment exhibited a larger contact area than the hex-type abutment by approximately 2.5% to 3.5% in contrast to the internal surface area of the implant. When the screw tightening torque of 30 Ncm was applied, the rotational displacement of the hex-type abutment was approximately 0.54 degrees and the round-type was approximately 1.16 degrees under clockwise moment loading.
Conclusion: Within the limitations of this study, it can be assumed that the hexagonal design of the abutment acts as rotational resistance against moments.
Keywords: 3D finite element model, implant rotation, positioning hex, tapered internal implant, von Mises stress
DOI: 10.11607/jomi.7763, PubMed ID (PMID): 32142565Pages 289-296c, Language: English
Purpose: To evaluate the interobserver and intraobserver agreement between prosthodontists when measuring interproximal peri-implant bone levels from digital periapical radiographs and to introduce a radiographic quality index for periapical imaging assessment.
Materials and Methods: Periapical radiographs of 122 single implants in the anterior and posterior regions with two categories of imaging quality (ie, optimal and suboptimal) were assessed. Six prosthodontists were asked to linearly measure the distance from the first bone-to-implant contact to the implant platform/shoulder (DIB) using an image processing program (ImageJ 1.48u4, NIH). The procedure was repeated after 3 to 4 weeks. Interobserver and intraobserver agreements were evaluated by intraclass correlation coefficient and kappa. A radiographic quality index developed for periapical imaging assessment has been introduced in this study. Each implant was classified into two categories according to the implant type and the quality of the radiographic image.
Results: There were significant interobserver differences (P < .001). Most of the discrepancies between repeated measures were below 0.5 mm (range: 0.37 [SD ± 0.76] to 0.55 [SD ± 0.68]). The interobserver and intraobserver agreements on the bone-level values were "fair to moderate" regardless of the implant type and radiographic quality. With optimal image quality in tissue-level images, "substantial agreement" could be achieved. There was no significant effect of the implant level type (P = .973).
Conclusion: Image quality, as well as the interpreter, influenced the measurements' reproducibility by prosthodontists. Bone height assessments at bone-level implants seem to be slightly more variable compared with tissue-level assessments; however, there were no significant differences. Specific guidelines on how to estimate DIB for calibration purposes in the case of suboptimal radiographic image quality and how to obtain optimal images need to be developed. The radiographic quality index for periapical imaging assessment is expected to be adopted in future studies.
Keywords: bone height assessment, bone level, bone loss, dental implants, intraoral radiographs, radiographic image enhancement, radiography, reproducibility of results
DOI: 10.11607/jomi.7554, PubMed ID (PMID): 32142566Pages 297-304, Language: English
Purpose: The goal of this study was to compare bone graft materials in mandibular third molar extraction sockets and to monitor bone remodeling and complications.
Materials and Methods: Patients with bilateral, impacted mandibular third molars were involved. Twenty-four patients were planned to be randomly assigned to three possible treatments: (1) the control sockets were left empty; (2) the socket was filled with bovine xenograft (Bio-Oss); or (3) the socket was filled with albumin-impregnated bone allograft (BoneAlbumin). Postoperative pain during the first week was determined with the visual analog scale. Cone beam computed tomography (CBCT) images were taken at 6 and 12 weeks and 1 year postoperatively for micromorphologic analysis and measurement of pocket depth at the second molar. Patients and image analyses were blinded toward the treatment group (randomized double-blind split-mouth design).
Results: Postoperative pain was lowest in the allograft group (control: 5.06 ± 0.53; xenograft: 5.85 ± 0.42; allograft: 3.94 ± 0.52; P < .05). At weeks 6 and 12, early signs of remodeling were observed in the allograft group and the controls, while bone xenograft was still demarcated from the host bone. The 1-year CBCT images showed complete remodeling and integration of allograft with natural trabecular structure, while the xenograft particles were still visible. Support for the second molar was significantly better, as evidenced by less deep and prevalent pockets in the allograft-filled group compared with the controls (P = .017).
Conclusion: Filling an extraction socket with albumin-integrated allografts provides superior bone regeneration compared to either native bone buildup or xenograft application or socket regeneration without bone grafting.
Keywords: 3D, albumin, biomaterials, bone graft
DOI: 10.11607/jomi.7419, PubMed ID (PMID): 32142567Pages 305-312, Language: English
Purpose: To analyze the impact of microthreads on the stresses generated in peri-implant bone surrounding reduced-diameter zirconia and titanium implants under loading.
Materials and Methods: Two custommade zirconia implants, microthreaded or smooth neck, and two titanium replicas were made. Strains were recorded in the peri-implant region under 200-N vertical load. Two three-dimensional finite element models were created. Zirconia and titanium implants were tested under 200-N vertical load and 150-N oblique load at 30, 45, and 60 degrees.
Results: The lowest peri-implant strain (40 ± 6 με) under vertical load was related to the microthreaded zirconia implant. Oblique load showed higher von Mises stress on bone in comparison with vertical load. The von Mises stress increased by increasing the load angle by approximately 2 MPa per degree. Under oblique load, implants showed more stress in peri-implant bone and the implant itself. On the other hand, total strains were within physiologic limits in all tested cases.
Conclusion: Stresses within the peri-implant cortical bone around the reduced-diameter implant with microthreads appeared to be superior compared with the smooth-neck one. Reduced-diameter zirconia implants induced less stress on bone in comparison with the titanium implants, suggesting that zirconia is a feasible alternative for titanium.
Keywords: finite element model, implant, reduced-diameter, single-piece, strain gauge
DOI: 10.11607/jomi.7694, PubMed ID (PMID): 32142568Pages 313-319, Language: English
Purpose: Bone regeneration procedures are often evaluated based on biologic aspects only. As regenerated bone also has to ensure primary implant stability, the goal of this study was to determine the mechanical quality of regenerated bone.
Materials and Methods: Six adult minipigs were allocated for this experiment with four mandibular study sites each established following tooth removal. Two different types of bovine bone mineral as well as autogenous bone were used for augmenting three-walled defects, while native bone served as the control. Implants were placed after 12, 18, and 24 weeks of healing, and bone quality was determined using intraoperative compressive testing (BoneProbe), insertion torque measurements, and resonance frequency analysis. The mandibles were then harvested for determining bone mineral density (BMD) and bone-to-implant contact (BIC). Statistical analysis was based on two-way analysis of variance of aligned rank transformed data and Spearman's rank correlation tests (α = .05).
Results: The effects of the factors healing time and material on the parameters tested were too small to be significant (P ranging from .34 to .98). Weak correlations were observed for implant insertion torque with BoneProbe measurements in the cortical (0.481; P = .032) and in the trabecular area (0.639; P = .002). BoneProbe measurements in the trabecular part and in the cortical part also correlated with each other (0.477; P = .035).
Conclusion: While differences may exist between bone regenerated using different biomaterials with respect to biologic behavior, differences in the mechanical properties determining primary implant stability seem to be minor. Implant insertion torque measurements appear to be a reliable tool for determining bone quality if only one specific implant type is considered.
Keywords: bone augmentation, bone mineral density, bone-to-implant contact, compressive testing, mechanical bone quality
DOI: 10.11607/jomi.7606, PubMed ID (PMID): 32142569Pages 320-329, Language: English
Purpose: The aim of this study was to compare how two innovative laser titanium surfaces and sandblasted and acid-etched surfaces influence human osteoblast behavior during osteogenesis and the initial phases of bone deposition.
Materials and Methods: Human osteoblasts from human adipose stem cells were sorted by flow cytometric analysis and induced to differentiate. After 40 days, the osteogenic differentiation was detected by alizarin red staining, and the alkaline phosphatase (ALP) was evaluated with western blot (WB) and real-time reverse transcriptase-polymerase chain reaction (RT-PcR) analysis. After confluence, human osteoblasts were cultured onto two different innovative laser-obtained titanium surfaces (L1 and L2) and compared with one sandblasted and acid-etched (SBAE) surface as the control. At different times, human osteoblast behavior was evaluated with cell proliferation viability assay (MTT), scanning electron microscopy (SEM), energy-dispersive x-rays (EDAX), osteogenic markers with RT-PcR, and WB analysis of matrix extracellular phosphoglycoprotein (MEPE), ALP, and osteocalcin (OCN).
Results: After cell sorting, the human osteoblasts from human adipose stem cells showed increasing values of ALP mRNA and protein expression. The osteogenic differentiation was confirmed by quantitative alizarin red staining assay. Profilometric and SEM analysis showed relevant differences between SBAE, L1, and L2 specimens. After 20 days of culture onto titanium samples, SEM evaluation showed a small number of human osteoblasts and isolated sites of bone matrix deposition in SBAE specimens. At the same time, on L1 surfaces, only an osteoblast mono-layer with initial bone deposition was found, while on L2 specimens, there was a thick network with flattened large stellate cells, many cellular interconnections with strong titanium adhesion, and a large complex mineralized structure of crystal bone. After 20 days, for all titanium samples, human osteoblasts culturing EDAX analysis showed the absence of impurities and a higher bone matrix deposition in L2 specimens compared with L1 and SBAE samples.
Conclusion: The innovative microtopography and nanotopography laser-induced surface showed high biocompatibility with primary human osteoblast cultures and the absence of impurities. The innovative laser texture was capable of influencing the osteogenic process, confirming the critical role of titanium surface characteristics in the cell adhesion and bone deposition during the early phases of osseointegration. The association of human adipose stem cells and titanium surfaces laser-induced with an innovative procedure could generate promising improvements and developments in orthopedics, maxillofacial, and dental implant surgery.
Keywords: bone, human osteoblasts, laser titanium surface, osseointegration, titanium dental implant
DOI: 10.11607/jomi.7541, PubMed ID (PMID): 32142570Pages 330-341, Language: English
Purpose: To evaluate the factors affecting peri-implant marginal bone level of single platform-switched implants with a smooth neck placed at gingival level (tissue level) using a flapless technique.
Materials and Methods: Consecutive healthy patients requiring dental implant rehabilitations were enrolled in this study. Titanium implants with a zirconium-oxide–blasted surface and a platform-switch neck tulip configuration were used. Loading was performed 3 months after insertion with a provisional resin crown and after approximately 15 days with a definitive ceramic crown. Peri-implant marginal bone level (MBL) was measured on periapical radiographs at 1, 3, 6, 12, 24, 36, and 48 months by a blinded assessor. The following parameters were evaluated: location (maxillary/mandibular), position (anterior/posterior), sex (male/female), smoke (yes/no), implant placement timing (immediate, early, delayed), gingival thickness (thin/thick), endodontically treated adjacent teeth (yes/no), and diameter (3.8/4.25/5.0 mm). Multilevel analyses exploring factors associated with MBL at 36 and 48 months were performed.
Results: A total of 76 patients (42 women, 34 men; mean age: 55.6 ± 10.7 years) received 128 implant rehabilitations. The survival rate was 98.4%. MBL displayed an initial increase during the first months from insertion (preload period). Cumulative mean MBL at T48 was 0.99 ± 0.68, which was not statistically significant from the values at T24 to T36 (P > .05). Mandibular location, delayed implants, and presence of adjacent endodontically treated teeth showed higher bone loss at 36 months (P < .05). Interestingly, at 48 months, only implant placement timing showed statistically significant differences. Delayed implants showed increased bone loss compared with both early and immediate groups (P < .05). Multilevel analysis confirmed the statistical significance of implant location (P = .031; 95% CI: 0.031 to 0.659), endodontically treated adjacent teeth (P = .001; 95% CI: –1.228 to 0.859), and implant placement (P = .045; 95% CI: 0.003 to 0.337) as factors affecting MBL at 36 months. All the investigated parameters, with the only exception being the implant placement group (P = .020; 95% CI: 0.334 to 1.432), were not statistically significant at 48 months (P > .05).
Conclusion: Platform-switched implants placed nonsubmerged with a flapless approach showed a reduced bone loss progression in the first 4 years, as MBL remained stable at longer times (36 and 48 months). Implants placed with early and immediate timing showed reduced bone loss compared with delayed implants.
Keywords: best clinical practice, dental implants, flapless surgery, MBL, platform-switch
DOI: 10.11607/jomi.7784, PubMed ID (PMID): 32142571Pages 342-349, Language: English
Purpose: To evaluate the effect of continuous tooth eruption on the outcomes of single-implant–supported restorations in the anterior maxilla of adults.
Materials and Methods: Seventy-six patients (age: 21 to 78 years) treated with single-implant–supported restorations in the esthetic zone were included. Radiographs obtained at crown placement and follow-up examinations from 1 to 15 years postloading were analyzed with regard to vertical incisal plane changes of the implant-supported crown relative to adjacent teeth.
Results: Infraocclusion increased over time by 0.08 ± 0.02 mm/year. Infraocclusion was more pronounced (P = .04) for delayed (0.09 mm/year) versus immediate implant placement (0.06 mm/year) and for younger versus older adults (0.0013 mm/year per additional year of age; P = .014). No statistically significant association between infraocclusion and sex, ethnicity, implant site, timing of implant temporization, surgical protocol, and type of restoration was found.
Conclusion: Infraocclusion of single-implant–supported maxillary anterior restorations may result in esthetic concerns over time. Greater infraocclusion occurs in delayed implant placement and in younger individuals.
Keywords: complication, esthetics, infraocclusion, infraposition, tooth eruption
DOI: 10.11607/jomi.7843, PubMed ID (PMID): 32142572Pages 350-356, Language: English
Purpose: To evaluate the dimensional variations after elevation of the maxillary sinus floor and the healing of the antrostomy left unprotected or protected by a collagen membrane.
Materials and Methods: Twenty patients were included in the study. After the elevation of the sinus mucosa, natural bovine bone was grafted into the elevated space. In 10 randomly selected patients, a native collagen membrane made of porcine corium was placed on the antrostomy (membrane group). In the other 10 patients, the antrostomy was left uncovered (no-membrane group). Cone beam computed tomography (CBCT) images were taken for all patients before surgery (T0), 1 week after sinus floor augmentation (T1), and after 9 months of healing (T2), and evaluations of dimensional variations over time of soft and hard tissues were performed.
Results: At T1, the elevation of the sinus floor in the middle aspect was 12.5 ± 3.8 mm and 11.9 ± 3.6 mm in the membrane and no-membrane groups, respectively. At T2, the reduction in height of the elevated space was 0.6 ± 0.9 mm and 0.8 ± 0.8 mm in the membrane and no-membrane groups, respectively. The elevated area decreased between ~10% and 11% in the membrane group and between ~15% to 20% in the no-membrane group. However, no statistically significant differences were found.
Conclusion: The use of a collagen membrane to cover the antrostomy after sinus floor elevation did not produce significant clinical effects on dimensional variations over time.
Keywords: antrostomy, biomaterials, CBCT, randomized controlled clinical trial, surgery
DOI: 10.11607/jomi.7731, PubMed ID (PMID): 32142573Pages 357-365, Language: English
Purpose: Different titanium bases for implant-supported prostheses can present different mechanical behavior. The goal of this study was to evaluate the torque before and after fatigue, the load to failure, and stress concentration of zirconia restorations cemented or notched to a titanium base.
Materials and Methods: Forty implants were included in polyurethane cylinders and divided into two groups: zirconia restoration cemented on a titanium base and zirconia restoration notched on a titanium base. The specimens had their torque loosening and vertical misfit evaluated before and after cyclic fatigue (200 N/2 Hz/2 × 106 cycles/37°C). Load to failure was evaluated in a universal testing machine (1 mm/min, 1,000 kgf). Failures were evaluated by scanning electron microscopy. Three-dimensional models were created, and the stress concentration was calculated using the finite element method. Data from the in vitro tests were submitted to two-way analysis of variance and Tukey test (α = .5).
Results: The cemented restorations presented less torque loosening (19.79 to 15.95 Ncm), lower vertical misfit (3.7 to 10.5 μm), lower stress concentration in the restoration (88.2 to 99.8 MPa), and higher fracture load (451.3 to 390.8 N) than notched restorations.
Conclusion: The presence of a cement layer between the restoration and titanium base reduced the susceptibility to abutment screw loosening, improved the resistance to compressive load, and reduced the stress concentration in the restoration.
Keywords: 3D, biomechanics, CAD/CAM, finite element analysis, prosthodontics
DOI: 10.11607/jomi.7488, PubMed ID (PMID): 32142574Pages 366-378, Language: English
Zygomatic-related implant rehabilitation differs from traditional implant treatment in biomechanics, clinical procedures, outcomes, and eventual complications such as soft tissue incompetence or recession that may lead to recurrent sinus/soft tissue complications. The extreme maxillary atrophy that indicates the use of zygomatic implants prevents use of conventional criteria to describe implant success/failure. Currently, results and complications of zygomatic implants reported in the literature are inconsistent and lack a standardized systematic review. Moreover, protocols for the rehabilitation of the atrophic maxilla using zygomatic implants have been in continuous evolution. The current zygomatic approach is relatively new, especially if the head of the zygomatic implant is located in an extramaxillary area with interrupted alveolar bone around its perimeter. Specific criteria to describe success/survival of zygomatic implants are necessary, both to write and to read scientific literature related to zygomatic implant–based oral rehabilitations. The aim of this article was to review the criteria of success used for traditional and zygomatic implants and to propose a revisited Zygomatic Success Code describing specific criteria to score the outcome of a rehabilitation anchored on zygomatic implants. The ORIS acronym is used to name four specific criteria to systematically describe the outcome of zygomatic implant rehabilitation: offset measurement as evaluation of prosthetic positioning; rhino-sinus status report based on a comparison of presurgical and postsurgical cone beam computed tomography in addition to a clinical questionnaire; infection permanence as evaluation of soft tissue status; and stability report, accepting as success some mobility until dis-osseointegration signs appear. Based on these criteria, the assessment of five possible conditions when evaluating zygomatic implants is possible.
Keywords: criteria of success, ORIS, review (narrative), ZAGA, zygomatic implants, zygomatic success code
DOI: 10.11607/jomi.7245, PubMed ID (PMID): 32142575Pages 379-385, Language: English
Purpose: To assess longitudinal volumetric changes during immediate implant placement with simultaneous intentional retention of the buccal aspect of the root.
Materials and Methods: This study assessed 10 cases drawn from a previously reported cohort that had study casts available pretreatment and at least 2 years after periodontal ligament (PDL)–mediated immediate implant placement. Gypsum casts were scanned using a laser scanner and converted into digital three-dimensional rendered files. The digital casts were superimposed, and semi-automated subtractive assessment was performed via specialized software.
Results: Data from 10 patients with a minimum of 3 years follow-up (median follow-up time: 42 months) were analyzed. Each person contributed one implant site in this study. All implants successfully maintained osseointegration during the follow-up period and demonstrated optimal soft tissue stability. Changes during the observation period ranged from 0.19 mm (95% confidence interval [95% CI]: 0.10 to 0.28) in the midfacial region 6 mm apical to the mucosal zenith to –0.06 mm (95% CI: –0.14 to 0.02) at 5 mm apical to the base of the distal papilla. All changes were noninferior to pre-extraction baseline measurements based on a 0.5-mm noninferiority margin.
Conclusion: The intentional retention of the buccal aspect of the root with its periodontal apparatus during immediate implant placement led to optimal soft tissue dimensional stability in the esthetic zone. This technique holds promise for clinical application, and further controlled clinical studies are warranted to determine the comparative clinical benefit from the use of this procedure.
Keywords: flapless procedure, immediate placement, PDL-mediated implant placement, surgical procedure
DOI: 10.11607/jomi.7776, PubMed ID (PMID): 32142576Pages 386-394, Language: English
Purpose: Patients who have a vertical growth pattern are more prone to complete alveolar bone growth later and run a higher risk for inhibition of growth and infraposition after implants have been placed. Moreover, it has been suggested for the same category of patients that craniofacial height may influence the alveolar bone morphology of the anterior maxilla during growth. Hence, it is important to identify such patients early when considering implant treatment in young patients. The purpose of this study was to investigate the height and width of the alveolar bone in the anterior maxilla in subjects with different craniofacial heights to assess if there is a relation between craniofacial height and the dimensions of the alveolar bone in the anterior part of the maxilla.
Materials and Methods: Measurements on cephalograms and cone beam computed tomography (CBCT) images of the maxilla from 180 fully dentate subjects were analyzed and categorized into three angle groups based on the craniofacial height: low-, normal-, and high-angle groups. Measurements of the alveolar bone were taken interradicular, at six reference points distributed between the first premolar regions in the maxilla. The height and width of the alveolar bone were measured with a standardized technique at 3, 6, 9, and 12 mm from the top of the alveolar process.
Results: Significant differences were found regarding the height of the alveolar bone in all the subgroups and regarding the width in the 9- and 12-mm subgroups, and between low-/normal- and low-/high-angle groups, where the high-angle group represented the thinnest alveolar bone. A significant difference was found between male and female patients concerning all dimensions of the alveolar bone.
Conclusion: There is a relation between craniofacial height and the dimensions of the alveolar bone in the anterior part of the maxilla. Craniofacial height is an important factor to analyze when implant treatment is considered in the maxillary anterior region. This identification can preferably be carried out early in young patients who are still growing when various treatment options can still be considered.
Keywords: 3D, alveolar bone height, alveolar bone width, craniofacial height, growth, radiology
DOI: 10.11607/jomi.7833, PubMed ID (PMID): 32142577Pages 395-405j, Language: English
Purpose: To provide a long-term comparison of metal-acrylic and zirconia implant-supported fixed complete dental prostheses.
Materials and Methods: Patients treated with a metal-acrylic or zirconia fixed implant prosthesis with a minimum 5-year follow-up were included. All complications were registered, along with events such as peri-implantitis and implant failure. Survival and all costs associated with the prostheses were assessed to provide an overall evaluation of each type of fixed implant prosthesis protocol.
Results: Seventy-four rehabilitated arches (43 metal-acrylic, 31 zirconia, mean follow-up: 8.7 ± 3.37 years) were included. Delayed complications accompanied the metal-acrylic prostheses more frequently. In both groups, single tooth chipping/fracture was the most prominent minor complication, and incidence of multiple teeth and framework fracture was the most frequent major complication. Zirconia fixed implant prostheses demonstrated higher prosthetic survival rates than the metal-acrylic prostheses (93.7% ± 5.5% at 5 years vs 83.0% ± 11.1%). No difference was observed for peri-implantitis or implant failure. The initial cost for zirconia prosthesis fabrication was significantly higher than metal-acrylic hybrids (an estimated difference of $7,829 [P < .001]); however, due to reduced complication rates for the zirconia fixed implant prosthesis, maintenance and treatment for complications did not greatly differ between groups.
Conclusion: Within the limitations, zirconia fixed implant prostheses presented higher initial costs than metal-acrylic hybrids, however, with satisfactory outcomes, reduction of overall complications, and superior survival rates.
Keywords: CAD/CAM, ceramics, dental implants, fixed implant prostheses, zirconia
DOI: 10.11607/jomi.7751, PubMed ID (PMID): 32142578Pages 406-414, Language: English
Purpose: When encountering a buccal bone defect during implant placement, guided bone regeneration (GBR) is a well-accepted method for bone reconstruction. However, it is still unclear if the esthetic and patient-reported outcomes are comparable to implants placed in native bone. The purpose of this prospective trial was to compare implants placed with a GBR procedure for a small (≤ 4 mm) buccal defect with implants placed completely in native bone (control).
Materials and Methods: Patients were allocated to the GBR group or control group during implant placement in the esthetic zone. Implants were placed after at least 12 weeks of healing of the extraction sockets. A buccal bone defect of ≤ 4 mm resulted in allocation to the GBR group. Follow-up was performed until 12 months after loading. Outcome measurements were as follows: esthetic scores, patient-reported outcome measurements, implant survival and complications, clinical indices, and radiographic measurements.
Results: In total, 45 patients were included, of which 23 underwent a GBR procedure after implant placement, and in 22 patients no GBR was necessary. No significant differences in esthetic outcomes were seen between the two groups. At the final follow-up, a mean pink esthetic score (PES) of 7.8 (SD: 1.5) was seen for the GBR group and 8.4 (SD: 1.4) for the control group. Regarding the white esthetic score (WES), a mean of 9.1 (SD: 1.0) was found for both groups. Patients of both groups were equally satisfied with their mucosa and crown. A mean visual analog score (VAS) for the soft tissues of 8.6 (SD: 1.0) in the GBR group and 8.8 (SD: 0.9) for the control group was noted. A mean VAS of 9.2 (SD: 0.8) was noted for the crown in the GBR group and 8.6 (SD: 2.0) in the control group. Implant survival was 100%, and there were no significant differences in complications, plaque/bleeding/ gingiva indices, width of attached mucosa, and marginal bone loss.
Conclusion: Implants placed in the esthetic zone with GBR or complete native bone coverage showed successful esthetic outcomes and satisfied patients with predictable clinical and radiographic parameters after more than 1 year of loading. Within the limits of this study, GBR for a small buccal bone defect seems to be a reliable technique with good esthetics and patientreported outcomes.
Keywords: esthetics, guided bone regeneration, patient-reported outcomes, prospective controlled clinical trial
DOI: 10.11607/jomi.7950, PubMed ID (PMID): 32142579Pages 415-422, Language: English
Purpose: The aim of this study was to assess the radiographic and clinical outcomes of extra-short implants either alone or in conjunction with osteotome sinus floor elevation and to compare these with regularsized implants in the posterior atrophic maxilla.
Materials and Methods: Systemically healthy, nonsmoker individuals having at least one tooth gap in the posterior maxilla were included in the study. When the residual bone height was < 4 mm, an extra-short implant (4 to 6 mm) in conjunction with osteotome sinus floor elevation was placed; when the residual bone height was between 4 and 7 mm, an extra-short implant alone was placed; and when it was ≥ 8 mm, a regular implant (8 to 10 mm) was placed. The implants were uncovered at 4 months, and porcelain-fused-to-metal crowns were fabricated. Crestal bone level, change in the crestal bone level, crown-to-implant ratio, and residual bone height were measured at baseline and 6 and 18 months postloading.
Results: Thirty patients (15 men, 15 women, age range: 30 to 73 years) received 80 implants. One implant in the extra-short implant (n = 27 implants) and regular implant (n = 24 implants) groups and two implants in the extra-short implant with osteotome sinus floor elevation group (n = 29 implants) failed before loading. Crestal bone level was significantly higher in the regular implant group compared with the extra-short implant with osteotome sinus floor elevation group at 18 months (P < .028). Crestal bone level change between 6 and 18 months was significantly lower in the extra-short implant + osteotome sinus floor elevation group compared with the regular implant group (P = .003). There was no correlation between the crestal bone level, crestal bone level change, and prosthetic and implant characteristics (P > .05).
Conclusion: Extra-short implants placed either in native bone or in conjunction with osteotome sinus floor elevation may provide similar clinical and radiographic outcomes that are comparable to those obtained with regular implants. Both extra-short implant placement methods can be promising noninvasive treatment options for the posterior maxilla, and implant dimension, crown length, crown-to-implant ratio, and residual bone height may not affect the crestal bone level change, at least in the short term.
Keywords: dental implants, maxillary sinus floor augmentation, minimally invasive surgery
DOI: 10.11607/jomi.7869, PubMed ID (PMID): 32142580Pages 423-431, Language: English
Purpose: The aim of this crossover study was to evaluate patient satisfaction and oral health related– quality of life (OHRQoL) with different connectors used for implant-retained overdentures in subjects with resorbed mandibles.
Materials and Methods: Eighteen edentulous patients with atrophied mandibular bone received traditional maxillary and mandibular dentures (control). After 3 months, two implants were inserted in the canine regions. Three months later, each patient received the following overdentures using a crossover design: (1) bar overdentures, (2) telescopic overdentures, and (3) stud overdentures. Patient satisfaction (primary outcome) was measured by visual analog scale (VAS). OHRQoL (secondary outcome) was measured by oral health impact profile (OHIP-14). Questions of VAS and OHIP-14 were evaluated after 3 months of using conventional dentures, bar overdentures, telescopic overdentures, and stud overdentures.
Results: For all questionnaires, conventional dentures recorded significantly lower satisfaction than implant overdentures. Stud overdentures showed significantly higher satisfaction with maxillary denture comfort, selfconsciousness, and feeling that the prosthesis is a part of the patient compared with other attachments. Bar and telescopic overdentures showed higher satisfaction during biting of hard and soft foods, while telescopic and stud overdentures showed higher satisfaction with oral hygiene. No significant differences between attachments regarding other VAS and OHIP-14 questions were noted.
Conclusion: Implant overdentures for subjects with mandibular bone resorption improved patient satisfaction and OHRQoL compared with traditional dentures regardless of the form of attachments. However, studs are more advantageous in terms of comfort with maxillary overdentures, self-consciousness, and feeling that the prosthesis is a part of the patient. Bar and telescopic attachments had more satisfaction during biting of soft and hard foods, while telescopic and stud attachments had more satisfaction with oral hygiene.
Keywords: attachments, bar, locator, OHRQoL, overdenture, satisfaction, telescopic
Online OnlyDOI: 10.11607/jomi.8065, PubMed ID (PMID): 32142581Pages e21-e26, Language: English
Different surgical approaches including the slot and the extrasinus techniques have been described to overcome disadvantages of the original Brånemark technique for the placement of zygomatic implants. A new concern associated with zygomatic implants placed externally to the maxillary wall is the possibility of disturbing buccal soft tissues, ending up with a dehiscence and a potential infective problem. Recently, a new methodology known as the Zygoma Anatomy-Guided Approach (ZAGA) has been described based on the concept of delivering specific therapy for each patient. ZAGA involves a variety of possibilities of implant trajectory from the intrasinus to an eventual extrasinus passage according to variations in patient anatomy. ZAGA methodology includes a rationale of how to prevent most of the reported complications of zygomatic implants. The objective of this technical note is to introduce the "Scarf Graft" as a part of the ZAGA protocol intended to prevent soft tissue dehiscence around extramaxillary zygomatic implants. A pediculated connective tissue graft is placed around the neck of the extramaxillary zygomatic implants. The increased connective tissue thickness consistently gives stable gingival tissue for prevention of recession. Currently, the treatment of soft tissue dehiscence around zygomatic implants does not have predictable results. Protocols for its prevention, such as the proposed ZAGA Scarf Graft, should be incorporated if an eventual dehiscence is foreseen.
Keywords: extramaxillary implants, Scarf Graft, soft tissue dehiscence, soft tissue recession, ZAGA, zygomatic implants