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1.
Nawakamon Suriyan Lertrit Sarinnaphakorn George R. Deeb Sompop Bencharit 《The Journal of prosthetic dentistry》2019,121(3):411-416
Statement of problem
Conventional guided implant surgery promises clinical success through implant placement accuracy; however, it requires multiple drills along with surgical sleeves and sleeve adapters for the horizontal and vertical control of osteotomy drills. This results in cumbersome surgery, problems with patients having limited mouth opening, and restriction to specific drill or implant manufacturers. A protocol for using trephination drills to simplify guided surgery and accommodate multiple implant systems is introduced.Purpose
The purpose of this clinical study was to evaluate the accuracy of implant placement using this novel guided trephine drill protocol with and without a surgical sleeve.Material and methods
Intraoral scanning and preoperative cone beam computed tomography (CBCT) scans were used for implant treatment planning. Surgical guides were fabricated using stereolithography. Implant surgery was performed using the guided trephination protocol with and without a surgical sleeve. Postoperative CBCT scans were used to measure the implant placement deviations rather than the implant planning position. Surgical placement time and patient satisfaction were also documented. One-tailed t test and F-test (P=.01) were used to determine statistical significance.Results
Thirty-five implants in 17 participants were included in this study. With a surgical sleeve, implant positional deviations were 0.51 ±0.13 mm vertically, 0.32 ±0.10 mm facially, 0.11 ±0.11 mm lingually, and 0.38 ±0.13 mm mesially. Without a surgical sleeve, implant positional deviations were 0.58 ±0.27 mm vertically, 0.3 ±0.14 mm facially, 0.39 ±0.16 mm lingually, and 0.41 ±0.12 mm mesially. No statistically significant difference was found between the 2 protocols (P>.01), except that the sleeve group had greater vertical control precision (F-test, P=.006), reduced placement time, and the time variation was reduced (t test, P=.003; F-test, P<.001).Conclusions
This trephination-based, guided implant surgery protocol produces accurate surgical guides that permit guided surgery in limited vertical access and with the same guided surgery protocol for multiple implant systems. Guided sleeves, although not always necessary, improve depth control and reduce surgical time in implant placement. 相似文献2.
Alexander R. Edelmann Devang Patel Riley K. Allen Chad J. Gibson Al M. Best Sompop Bencharit 《The Journal of prosthetic dentistry》2019,121(3):404-410
Statement of problem
The design of porous tantalum trabecular metal–enhanced titanium (TM) dental implants promises improved osseointegration, especially when grafting materials such as demineralized bone matrix are used; however, studies are lacking.Purpose
The purpose of this retrospective study was to compare TM implants with conventional titanium alloy (Ti) implants with and without demineralized bone matrix in terms of peri-implant bone remodeling in the first year after implant loading.Material and methods
A chart review was used for all patients receiving Tapered Screw-Vent Ti and TM implants. Implants were placed and restored by a single provider between 2011 and 2015. Peri-implant bone remodeling was compared by using a paired t test (α=.05).Results
A total of 82 patients received 205 implants, 44 TM and 161 Ti implants (control). No implants failed in the TM group (survival rate of 100%), and 3 implants in total, 1 immediate, failed in the Ti groups (survival rate of 98.1%). TM implants exhibited a 0.28-mm bone gain on average, whereas the control group demonstrated 0.20 mm of marginal bone loss after the first year of implant loading. Multivariate logistic regression analysis demonstrated that the odds of having bone loss was 64% less (odds ratio: 0.36; 95% confidence interval: 0.14-0.94) in the TM group than in the Ti group after controlling for bone grafting, implant location, immediate placement, bone type, and pretreatment bone level.Conclusions
TM implants exhibited less peri-implant bone loss than the control Ti implants. 相似文献3.
Lisa A. Lang Sarah E. Hansen Norma Olvera Sorin Teich 《The Journal of prosthetic dentistry》2019,121(4):611-617
Statement of problem
Identifying factors that affect the clinical outcomes of implant therapy is important.Purpose
The purpose of this retrospective study was to determine whether implant location was a factor affecting the complication and failure rates of single-tooth implant-supported restorations in a predoctoral setting.Material and methods
The charts of 431 patients treated with a surgically placed dental implant and restored with a single crown in the predoctoral clinic were analyzed. Data on implant location, type of complication (surgical or prosthetic), and type of failure were collected and analyzed according to implant location using the Fisher Exact Test and Mantel-Haenszel Exact Chi Square Test analysis (α=.05).Results
The charts revealed 158 complications (68 surgical and 90 prosthetic) in 110 patients, and 3.9% of the implants failed. No statistically significant difference was found between the number of surgical complications or prosthetic complications in the maxilla and the mandible (P=.469).Conclusions
Jaw location (maxilla compared with mandible) of the implant had no statistically significant impact on the incidence of surgically or prosthetically related complications. No statistically significant difference was found in overall implant failures, surgical failures, and prosthetic failures between maxillary and mandibular implants. 相似文献4.
Björn Gjelvold Deyar Jallal Hadi Mahmood Ann Wennerberg 《The Journal of prosthetic dentistry》2019,121(3):498-503
Statement of problem
Different factors influence the degree of deviation in dental implant position after computed tomography–guided surgery. The surgical guide–manufacturing process with desktop 3D printers is such a factor, but its accuracy has not been fully evaluated.Purpose
The purpose of this in vitro study was to evaluate the deviation in final dental implant position after the use of surgical guides fabricated from 2 different desktop 3D printers using a digital workflow.Material and methods
Twenty 3D-printed resin models were prepared with missing maxillary premolar. After preoperative planning, 10 surgical guides were produced with a stereolithography printer and 10 with a digital light-processing (DLP) printer. A guided surgery was performed; 20 dental implants (3.8×12 mm) were installed, and a digital scan of the dental implants was made. Deviations between the planned and final position of the dental implants were evaluated for both the groups.Results
A statistically significant difference between stereolithography and DLP were found for deviation at entry point (P=.023) and the vertical implant position (P=.009). Overall lower deviations were found for the guides from the DLP printer, with the exception of deviation in horizontal implant position.Conclusions
The tested desktop 3D printers were able to produce surgical guides with similar deviations with regard to the final dental implant position, but the DLP printer proved more accurate concerning deviations at entry point and vertical implant position. 相似文献5.
Carlo Maiorana Pier Paolo Poli Anna Mascellaro Susanna Ferrario Mario Beretta 《Journal of cranio-maxillo-facial surgery》2019,47(5):805-814
Purpose
To evaluate the long-term outcome of dental implants placed with a staged procedure in resorbed alveolar ridges reconstructed with iliac crest autogenous onlay grafts.Materials and methods
All consecutive patients treated with iliac crest onlay bone grafts and dental implants were retrospectively evaluated. During the appointment, clinical and radiological examinations were conducted to assess implant survival. A survived implant was defined as an implant still stable and in function at the follow-up visit. Implant survival was estimated at the implant level using Kaplan-Meier analyses. The cumulative survival rate was estimated using a life-table analysis. Subgroup analyses were performed for age, position, and type of retention using the log-rank test. A p-value of <0.05 was considered statistically significant.Results
The cohort consisted of 21 female subjects receiving a total of 140 rough-surface titanium implants. Of them, 128 survived and 12 failed, yielding a cumulative survival rate of 91.1% over a median survival time of 312 months. Implants supporting cement-retained prostheses exhibithed lower survival rate compared to screw-retained restorations (p = 0.001).Conclusion
Implants placed in bone augmented with iliac crest onlay grafts showed high long-term survival rates. Cement-retained restorations were more prone to develop implant failures. 相似文献6.
Sameh Attia Jörg Wiltfang Philipp Streckbein Jan-Falco Wilbrand Thaqif El Khassawna Katharina Mausbach Hans-Peter Howaldt Heidrun Schaaf 《Journal of cranio-maxillo-facial surgery》2019,47(5):786-791
Purpose
Microvascular fibula flap surgery is a reliable and effective procedure for reconstructing the jaws after tumour surgery. This procedure allows the placement of dental implants after bone consolidation. This study was designed to evaluate the oral, functional, and aesthetic rehabilitation of tumour patients with immediate fibula transfer and dental implants and included assessment of diet, speech, and aesthetics.Materials and methods
The study included 34 patients who underwent ablative tumour surgery and immediate jaw reconstruction using a fibula free flap with consecutive rehabilitation by dental implants. In total, 134 implants were inserted into the transferred fibula. The functional and aesthetic results were assessed using a questionnaire. Implant loss and oral excursion were compared with diet type, speech ability, functionality, and patient satisfaction.Results
Of the 34 patients included in this study, 33 completed the questionnaire. Twenty-six patients (76%) could eat normally without the limitation of a hard or soft diet, 73% could speak intelligibly, and 31 rated the aesthetic result from good to excellent.Conclusion
The fibula flap with the early application of endosseous implants allowed primary immediate reconstruction of the jaw, significantly leading to functional and aesthetic satisfaction in patients who underwent ablative tumour surgery. 相似文献7.
Paul Weigl Georgia Trimpou Jonas Lorenz Georg-Hubertus Nentwig Hans-Christoph Lauer 《The Journal of prosthetic dentistry》2019,121(4):618-622
Statement of problem
Nonrigid retainer systems for removable implant superstructures are associated with negative effects such as rocking and increased load on the denture base. Rigid retainer systems such as telescopic crowns reduce these negative effects, but their fabrication demands highly skilled dental technicians and is therefore expensive. Whether a protocol with prefabricated retainers will reduce production time is unclear.Purpose
The purpose of this prospective clinical trial was to evaluate a prefabricated telescopic retainer and a treatment protocol including the intraoral luting of a framework.Material and methods
A total of 23 participants (15 women and 8 men with a mean age of 61.6 ±2.9 years) were included. After 3 dropouts, 21 removable dentures (9 mandibular and 12 maxillary) retained by 91 delayed loaded Ankylos implants were investigated. All implants were restored with prefabricated conically shaped abutments (SynCone-abutment). The prefabricated corresponding cone matrix was assembled intraorally into a metal frame with autopolymerizing resin. After a loading period of 3 years, a follow-up examination investigated the fit of the framework, the prosthetic aftercare, the technical failures, and the retention force. A questionnaire was used to evaluate participant satisfaction. In addition, laboratory fabrication time and costs were compared with those of individually fabricated restorations.Results
One mandibular implant was lost after 25 months (survival rate, 98.9%). The removable dentures showed no apparent rocking and minimal prosthetic maintenance during the 36-month trial. No dentures required relining. The retention force was scored as good in 17 participants and high (with 6 implants in the maxilla) and low (with 2 implants in the mandible) in 2 participants each. No technical failures occurred. An assessment of laboratory fabrication time and costs revealed reduced time and costs. Patient satisfaction was significantly increased (P<.001) over the entire observation time.Conclusions
The SynCone retainer presented a time- and cost-efficient treatment option with sufficient long-term retention for removable dentures and high patient satisfaction. Mandibular prostheses restored with 2 implants had limited success. 相似文献8.
Adrien Naveau Christophe Rignon-Bret Claudine Wulfman 《The Journal of prosthetic dentistry》2019,121(5):775-781.e1
Statement of problem
The success of single, anterior, implant-supported restorations relies on mechanical and esthetic outcomes. Titanium has been the most commonly used material for abutments, but zirconia is increasingly chosen for its appearance despite its unclear mechanical performance. Today, manufacturers market prefabricated, computer-aided design and computer-aided manufacturing (CAD-CAM) custom and zirconia abutments with titanium connections.Purpose
The purpose of this study was to systematically review the mechanical and esthetic outcomes of implant zirconia abutments used in the anterior region, considering the design changes of the past 5 years.Material and methods
An electronic search was conducted in Medline (PubMed) for studies on zirconia abutments. All clinical studies with at least a 1-year follow-up and case series (>5 abutments) published after 2013 were included. Mechanical and esthetic outcomes were collected.Results
Of the 231 retrieved studies, 20 remained for quantitative analysis. Twelve described mechanical outcomes, and 15 focused on esthetics, using mainly the pink esthetic score. Five articles reported abutment fractures and no chipping. No difference was found between prefabricated and custom abutments or internal and external implant connections regarding fractures or screw loosening. All authors reported “good to excellent” esthetic integration in terms of restorations and soft-tissue color and the presence and height of papillae. The most difficult esthetic parameters to achieve were root convexity, soft-tissue color, and texture and level of mucosa.Conclusions
Esthetics remain the major advantage of zirconia abutment when compared with titanium, despite reservations concerning the risk of mechanical complications. Data are lacking for zirconia abutments with titanium inserts, although the prospects for this design are promising. 相似文献9.
Oral Cenk Aktas Wolfgang Metzger Ayman Haidar Yahya Açil Aydin Gülses Jörg Wiltfang Catharina Marques Sacramento Frank Philipp Nothdurft 《Journal of cranio-maxillo-facial surgery》2019,47(4):661-667
Background
Promoting the directional attachment of gingiva to the dental implant leads to the formation of tight connective tissue which acts as a seal against the penetration of oral bacteria. Such a directional growth is mostly governed by the surface texture.Material and methods
In this study, three different methods, mechanical structuring, chemical etching and laser treatment, have been explored for their applicability in promoting cellular attachment and alignment of human primary gingival fibroblasts (HGFIBs).Results
The effectiveness of mechanical structuring was shown as a simple and a cost-effective method to create patterns to align HGIFIBs.Conclusion
Combining mechanical structuring with chemical etching enhanced both cellular attachment and the cellular alignment. 相似文献10.
Nynke Lie Hans-Albert Merten Kensuke Yamauchi Jörg Wiltfang Peter Kessler 《Journal of cranio-maxillo-facial surgery》2019,47(3):454-460
Introduction
In edentulous patients the form and size of the maxillary sinus vary greatly. Therefore sinus floor augmentation is a standard procedure for implantological purposes. As the sinus membrane cannot be characterized as periosteum, various augmentation materials are used.Hypothesis
an artificially generated space underneath the sinus membrane in the floor of the sinus will lead to spontaneous callus forming and a stable bony consolidation without augmentation material.Methods
Ten edentulous patients with highly atrophic maxillae were selected. Augmentation of the sinus floor was carried out in a split-mouth study design: On one side a combination of autogenous and xenogenous bone was used, and on the contralateral side a sinus membrane elevation was performed without using any substitutes. After a 6-month interval bone specimens from the test regions were harvested during implant placement.Results
Clear histological evidence of new bone formation was found in all human bone specimens. An active de-novo bone formation process could be proven by the presence of Haversian systems (osteons) displaying osteoblastic and osteoclastic activity.Conclusion
In the maxillary sinus of edentulous patients a spontaneous callus-derived de-novo bone formation is possible by elevating the sinus membrane without using augmentation materials. 相似文献11.
Bruna M. Vetromilla Lucas P. Brondani Tatiana Pereira-Cenci César D. Bergoli 《The Journal of prosthetic dentistry》2019,121(3):398-403.e3
Statement of problem
A consensus regarding which implant-abutment connection type would perform best in the anterior maxilla is lacking.Purpose
The purpose of this systematic review was to determine the best implant-abutment connection type for anterior single-tooth implants considering esthetics, success, and survival rates.Material and methods
An electronic search was conducted in MEDLINE, Scopus, Embase, and the Cochrane Library databases to identify clinical studies on single-tooth implants with external and internal hexagon, and/or Morse taper connections. These studies needed to describe at least one of the following outcomes: esthetic score, survival/success rate, or marginal bone loss. The included studies and reports were assessed for bias using the Cochrane risk of bias tool.Results
Of the 891 articles identified, 29 were selected and analyzed. The most common technical complications were abutment screw loosening and crown-cement loosening, while dehiscence and recession were the most common biological complications. The most frequent complications were dehiscence for external hexagon, crown-cement loosening for the internal hexagon, and ceramic fracture for the Morse taper. Esthetics were favorable for all connections, but the internal hexagon performed better. However, better results for marginal bone loss, success, and survival were found for the Morse taper. The global annual failure rate was 0.90% and 0.2% for Morse taper, 0.3% for external hexagon, and 2.2% for internal hexagon.Conclusions
This review suggests that Morse taper performs better for survival, success, and marginal bone loss. Internal hexagon performed better for esthetic parameters. Additional controlled studies are needed to provide stronger evidence because the evidence generated in this study was considered low. 相似文献12.
Hendrik Naujokat Sönke Harder Lara Yasemin Schulz Jörg Wiltfang Christian Flörke Yahya Açil 《Journal of cranio-maxillo-facial surgery》2019,47(3):484-490
Purpose
Successful implant therapy is based on fast, safe, and predictable osseointegration. Several surface modifications have been introduced to improve the bone-to-implant interaction. This in vivo study evaluates the impact of plasma surface conditioning on early wound healing and osseointegration.Materials and methods
A total of 16 dental implants with a sand-blasted and acid-etched surface were conditioned with cold atmospheric plasma prior to insertion in the frontal bone of four miniature pigs. Sequential fluorescence labeling was administered to label bone metabolism, and after 8 weeks, bone blocks were harvested for radiological, histological, and histomorphometrical evaluation.Results
The plasma conditioning had no impact on the morphology of the implant surface. The bone-to-implant contact ratio was 90.4% and 86.5%, the interthread bone density 72.5% and 63.4%, and the periimplant bone density 60.5% and 61.1%, in the plasma conditioned group and control group, respectively. Concentric bands of fluorescence enrichment indicated a chronological and homogenous mineralization of newly formed bone. No unwanted periimplant side effects were detected.Conclusion
The increased parameters for osseointegration in this in vivo study merit further investigation in prospective clinical trials. 相似文献13.
S.E.C.M. van de Vijfeijken R. Schreurs L. Dubois A.G. Becking 《Journal of cranio-maxillo-facial surgery》2019,47(4):542-547
Purpose
The aim of this study was to evaluate the accuracy of resection templates in cranioplasties in order to facilitate a one-stage resection and cranial reconstruction. Patients and methods: In three cases, cranial resections were combined with direct reconstructions using the principles of computer-aided design, manufacturing, and surgery. The precision of the resection template was evaluated through a distance map, comparing the planned and final result.Results
The mean absolute difference between the planned and actual reconstructed contour was less than 1.0 mm. After 3 years, no clinical signs of infection or rejection of the implants were present. The computed tomography scans showed no irregularities, and the aesthetic results remained satisfactory.Conclusion
One-stage resection and cranial reconstruction using a resection template, control template, and a prefabricated patient-specific implant of poly(ether-ether-ketone) (PEEK) proved to be a viable and safe method. 相似文献14.
Statement of problem
Short implants have been increasingly used in the aging society. However, studies which explain the difference of stress distribution according to different connections in short implant treatment are scarce.Purpose
The purpose of this finite element (FE) analysis was to evaluate the stress and strain distribution of short implants and surrounding bone under static and cyclic loading conditions with 4 different connections.Material and methods
Three-dimensional models of 4 types of implant systems were considered: internal tissue level, internal tissue level wide, internal bone level (IB), and external bone level. Each system had different types of abutment, implant, and screw with the resorbed mandibular segment of the bone block. Static FE analysis was performed under external loads of 200 N (vertical or 30-degree oblique) to each cusp tip. The strain distributions of the peri-implant bone and von Mises stress fields in the abutment, implant, and screw were evaluated. Based on the static FE results, a computational fatigue analysis was performed to predict the risk of fracture caused by fatigue accumulation of repetitive mastication.Results
Bone tissues in fatigue failure level (greater than 4000 με) were observed in the alveolar ridge and the plateaus close to the implant apex in all situations. Under the oblique loading condition, the total volume of the bone tissue in hypertrophy and fatigue failure levels (greater than 2500 με) was the largest at IB and the smallest at external bone level. Among the 4 situations, the highest stress occurred in the abutment (506.9 MPa) and implant (311 MPa) of IB. In fatigue analysis, fracture was only predicted in the IB abutment model (588?301 cycles), and cracking occurred in the lingual direction, where stress concentration occurred when the oblique load was applied.Conclusions
The abutment of IB showed the highest stress of the implant component, and internal tissue level model showed the highest strain of bone. In all groups, the bone strain values mostly appeared within physiologic capacity (under 4000 με). Various mechanical situations should be considered when using internal bone-level connections in short implants for replacing posterior teeth. 相似文献15.
Ankur Dahiya Nadim Z. Baba Mathew T. Kattadiyil Charles J. Goodacre Akshita Mann 《The Journal of prosthetic dentistry》2019,121(3):504-509
Statement of problem
Excess cement around dental implants is a significant cause of peri-implant inflammation. Research has focused on approaches to cement removal, the type of cement used, and the different instruments used for cement removal with titanium abutments. However, data comparing zirconia with titanium abutments are lacking.Purpose
The purpose of this in vitro study was to compare the effectiveness of excess cement removal from zirconia and titanium custom abutments using an explorer and to compare the effects of cement removal on the abutment surfaces.Material and methods
Implant analogs were placed in a cast in the position of the 2 maxillary central incisors. After creating similar emergence profiles for both the implant abutments, 18 zirconia and titanium custom abutments were fabricated with 1-mm subgingival finish lines on the facial and interproximal areas and an equigingival finish line on the palatal side. The crowns were cemented with zinc oxide-eugenol cement, and a steel explorer was used to remove the excess cement. All abutments were analyzed under a scanning electron microscope for cement remnants and scratches.Results
The mean surface area of cement remnants on the zirconia abutments was 778 ±113 μm2, and for titanium abutments, it was 1123 ±252 μm2, which in terms of the mean percentage area was 3.27% of the total surface area of zirconia and 4.71% of titanium abutments. Only a few abutments from each group showed scratches, and no deep scratches or gouges were observed.Conclusions
Zirconia and titanium abutments had statistically similar cement remnants. Scratches were observed on only a few specimens. 相似文献16.
Paulo Valdeci Worm Guilherme Finger Tobias Ludwig do Nascimento Carla Bittencourt Rynkowski Marcus Vinicius Martins Collares 《Journal of cranio-maxillo-facial surgery》2019,47(5):715-719
Objective
To evaluate the quality of life in patients with moderate or large cranial bone defects before and after late cranioplasty.Methods
Authors performed a prospective clinical trial including all consecutive patients that filled inclusion criteria during a period of 1 year. All patients answered the quality of life SF-36 questionnaire in 5 different times. Besides authors gathered information about the primary trauma and demographic characteristics.Results
A total of 70 consecutive patients were admitted to the hospital during the study period, and 62 were included in the project. Cranioplasty statistically improved patients' quality of life in all 8 domains after a 24 months follow-up.Conclusion
Cranioplasty has a significant impact over the quality of life in brain trauma victims who survived the primary trauma and harbor a large cranial bone defect. 相似文献17.
Jéssica Marcela de Luna Gomes Cleidiel Aparecido Araújo Lemos Joel Ferreira Santiago Junior Sandra Lúcia Dantas de Moraes Marcelo Coelho Goiato Eduardo Piza Pellizzer 《The Journal of prosthetic dentistry》2019,121(5):766-774.e3
Statement of problem
Consensus is lacking regarding the optimal number of implants for supporting complete-arch prostheses with good survival rates and lower prosthetic complications and marginal bone loss.Purpose
The purpose of this systematic review was to evaluate the influence of the number of implants used for complete-arch prostheses with at least 5 years of follow-up.Material and methods
A search was performed in the PubMed/MEDLINE, Scopus, and Cochrane Library databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria and was registered in The International Prospective Register of Systematic Reviews (CRD42016048468). The following was the population, intervention, comparison, outcome (PICO) question: Does the number of implants influence the longevity of complete-arch prostheses?Results
Nineteen studies including 1006 patients with a mean age of 61.44 years were selected for evaluation. The number of implants per jaw ranged between 2 and 9 in the maxilla, mandible, or both jaws. For implant survival rate in complete-arch prostheses with fewer than 5 implants per jaw, the pooled weighted event rate was 1.4% (I2=25.26%; P=.211) and 4.2% (I2=81.35%; P<.001) for complete arches with more than 4 implants per jaw. For the prosthesis survival rate, the pooled weighted event rate for a complete-arch with fewer than 5 implants per jaw was 1.5% (I2=0%; P=.677) and 9% (I2=17.33%; P=.304) for complete arches with more than 4 implants per jaw. For prosthesis complications for complete arches with fewer than 5 implants per jaw, the pooled weighted event rate was 19.9% (I2=93.5%; P<.001) and 24.5% (I2=88.89; P<.001) for complete arches with more than 4 implants per jaw. The mean marginal bone loss for complete arches with fewer than 5 implants per jaw was 1.22 ±0.49 mm (I2=99.46; P<.001) and 1.46 ±0.46 mm (I2=99.6; P <.001) for more than 4 implants per jaw.Conclusions
The current systematic review indicated no relationship of the number of implants used to support a complete-arch prosthesis with implant survival rate, prosthesis survival rate, prosthesis complications, or marginal bone loss in studies with follow-up periods of between 5 and 15 years. 相似文献18.
Yuehong Fan Gerald N. Glickman Mikhail Umorin Madhu K. Nair Poorya Jalali 《Journal of endodontics》2019,45(5):606-610
Introduction
This study aimed to introduce a novel method using cone-beam computed tomographic (CBCT) imaging and prefabricated grids to guide apical access during endodontic microsurgery and to compare its accuracy with that of the nonguided method.Methods
Forty-two roots from human cadaver jaws were selected. Twenty-one were randomly assigned to the experimental group (grid based) and their contralateral counterparts to the control group (nonguided). Preoperative CBCT images were used to design a drill path that intended to reach the palatal/lingual aspect of the roots without attempting to complete the osteotomy or to resect the entire root end. In the experimental group, prefabricated metal grids used during imaging and surgery acted as a reference in the design and drilling. Postoperative CBCT volumes were superimposed on the preoperative volumes, and the distances between the actual drill paths and the target points were measured. A dichotomized outcome of success versus failure was also recorded and compared. Statistical analysis was performed using the paired t test and Fisher exact test.Results
The mean deviation of the drill paths from the target points was 0.66 mm ± 0.54 mm (mean ± standard deviation) for grid-based drilling and 1.92 mm ± 1.05 mm (mean ± standard deviation) for nonguided drilling (P < .001). Grid-based drilling was on average 1.27 mm (95% confidence interval, 0.81–1.72 mm) closer to the target point than nonguided drilling. The probability of successful drilling was also significantly higher with grids than without grids (P = .02).Conclusions
The proposed method of guided osteotomy and root-end resection using prefabricated grids was more accurate than the nonguided method. 相似文献19.
Guilherme Berger Luiz Felipe de Oliveira Pereira Evelise Machado de Souza Rodrigo Nunes Rached 《The Journal of prosthetic dentistry》2019,121(5):865.e1-865.e7
Statement of problem
Evidence regarding the effect of different glass fiber reinforcement designs on the biomechanical behavior of implant-supported overdentures is lacking.Purpose
The purpose of this finite element analysis was to analyze the stress distribution in an implant-supported overdenture reinforced with a cast metal reinforcement bar and 4 different designs of unidirectional glass fiber to minimize the risk of denture base fracture.Material and methods
A 3D edentulous mandible incorporating an implant-supported overdenture model without reinforcement (control, CT) or reinforced with 1 cast metal bar reinforcement (CM) was placed over the top of the implants and 4 unidirectional glass fiber reinforcements. The glass fiber bundle was placed over the top of the implants (GF), or 2 bundled halves were placed over the top (GO) of, between (GB), or distal (GD) to implants. Three patterns of occlusal loading were simulated: L1, all artificial teeth loaded in the long axis; L2, all left-side teeth loaded in the long axis; and L3, posterior left-side teeth loaded obliquely (45 degrees).Results
Under L1 and L3, the tensile stresses were higher for CT, GD, and GO and lower for GF and CM. Under L2, no differences were seen between groups. Stresses were concentrated on the periphery of the O-ring connector, on the basal area, and on the middle-lingual region of the overdenture.Conclusions
Reinforcements placed in the middle region and over the top of the implants provided better load distribution. Unidirectional glass fiber behaved as cast metal when used to reinforce the implant-supported overdenture. 相似文献20.
Kaidiliya Yalikun Manabu Kanazawa Mariko Tanoue Shunsuke Minakuchi 《The Journal of prosthetic dentistry》2019,121(3):492-497