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Purpose: The purpose of this 3D finite element analysis was to evaluate the biomechanical effects of different materials used to fabricate occlusal devices to achieve stress distribution in simulated abutment screws, dental implants, and peri‐implant bone tissue in individuals who clench their teeth. Materials and Methods: Eight 3D models simulated a posterior maxillary bone block with three external hexagon implants (Ø4.0 × 7.0 mm) supporting a 3‐unit screw‐retained metal‐ceramic prosthesis with different crown connection (splinting), and the use of an occlusal device (OD). The OD was modeled to be 2‐mm thick. ANSYS 19.2 software was used to generate the finite‐element models in the pre‐and post‐processing phases. Simulated abutment screws and dental implants were evaluated by von Mises stress maps, and simulated bone was evaluated by maximum principal stress and microstrain maps by using a finite element software program. Results: The highest stress values in the dental implants and screws were observed in single crowns without OD (M1). Furthermore, the highest stress values and bone tissue strain were found in single crowns without OD (M1). The simulated material for the OD did not cause many discrepancies in terms of the stress magnitude in the simulated dental implant and abutment screw for both single and splinted crowns; however, more rigid materials exhibited lower stress values. Conclusion: The use of OD was effective in reducing stress in the simulated implants and abutment screws and stress and strain in the simulated bone tissue. The material used to simulate the OD influenced the biomechanical behavior of implant‐supported fixed prostheses, whereas splints with rigid materials such as PEEK and PMMA exhibited better biomechanical behavior. [ABSTRACT FROM AUTHOR]

Objective. To evaluate the influence of screw-tightening methods on the immediate and long-term stability of dental implant screw joints. Methodology. A total of 150 implants of three different implant systems with different diameters were used in this study. Each group was divided into three subgroups (n = 5), according to the tightening methods (A—tightening with recommended torque and retorque after 10 min; B—tightening with recommended torque, then loosening and immediate retorque; C—tightening with recommended torque only once). The operating time of tightening the assemblies was recorded. Ten minutes later, the immediate removal torque (IRT) (Ncm) was measured. After retightening the assemblies, a dynamic load between 20 and 200 N was applied for 105 cycles, and the postloading removal torque (PRT) (Ncm) was measured. Scanning electron microscopy (SEM) was used to observe the surface topography of the screws. Results. For different types of implants, the IRTs were 11.92 ± 1.04–34.12 ± 0.36 Ncm for method A, 11.64 ± 0.57–33.96 ± 0.29 Ncm for method B, and 10.30 ± 0.41–31.62 ± 0.52 Ncm for method C, and the IRTs of methods A and B were 6.28%–21.58% higher than that of method C (P ≤ 0.046). The PRTs were 4.08 ± 0.77–29.86 ± 0.65 Ncm for method A, 4.04 ± 0.40–29.60 ± 0.36 Ncm for method B, and 2.98 ± 0.26–26.38 ± 0.59 Ncm for method C, and the PRTs of methods A and B were 11.77%–44.87% higher than that of method C (P ≤ 0.016). The removal torque loss rates of methods A (12.49% ± 0.99%–65.88% ± 4.83%) and B (12.84% ± 0.96%–65.35% ± 1.95%) were 3.04%–7.74% lower than that of method C (16.58% ± 0.56%–71.10% ± 1.58%) (P ≤ 0.017). The operating time of method A was much longer than those of methods B and C (P < 0.001). The structural integrity disruption of the screw thread was observed according to the SEM results in all postloading groups. Conclusions. Method B (torquing and then loosening and immediate retorquing) increases the screw joint immediate stability by 6.28%–21.58% and the long-term stability by 11.77%–44.87% compared with method C (torquing only once), has comparable screw joint stability compared with method A (retorquing after 10 min), saves time and is recommended in clinical settings. [ABSTRACT FROM AUTHOR]

Key Clinical Message: We used a mixture of particulate bone grafts (xenografts/allografts) with tenting screws to prevent membrane collapse and covered the graft with a resorbable collagen membrane to guide bone regeneration. This strategy can exclude the need for additional procedures, such as non‐resorbable membranes and major block grafting surgeries. Although the initial outcomes are promising, continuous follow‐up is required to examine the stability of the newly regenerated bone and the long‐term success of the implant. This case demonstrates the use of particulate bone grafts covered with a resorbable collagen membrane and supported by tenting screws to correct horizontal alveolar ridge defects. A man in his 40s presented with missing maxillary anterior central and lateral incisors and required a fixed dental prosthesis. One year before, #12, #11, #21, and #22 had been extracted. The area showed horizontal and slight vertical bone loss. We used a mixture of particulate bone grafts (xenografts and allografts) with tenting screws to prevent membrane collapse and covered the graft with a resorbable collagen membrane to guide bone regeneration. After 6 months, complete bone regeneration was achieved, and the dental implants were submerged in the bone. After another 6 months, the patient was administered with a fixed dental prosthesis. This method can be used to correct horizontal alveolar ridge defects and achieve esthetic restoration without the need for more extensive procedures. [ABSTRACT FROM AUTHOR]

This study evaluated the pull-off force between titanium abutments and zirconia crowns that were bonded using four different cements and two abutment heights (AHs). In total, 24 titanium abutments (3-mm AH: n = 12; 5-mm AH: n = 12; taper: 7.5 degrees) and 24 zirconia crowns were designed, manufactured, cemented with one of four dental cements (one temporary, two semi-permanent, one permanent), stored in water for 24 hours, and thermocycled (37,500 cycles, equal to ~4 years in vivo). The pull-off force needed to separate the abutment and crown in each combination was determined eight times per combination of cement type and abutment height. Statistical analysis was conducted at a significance level of P < .05. The permanent self-adhesive composite cement showed a high pull-off force with a risk for crown fracture (mean: 381 N for 3-mm AH; 617 N for 5-mm AH). In contrast, the temporary zinc-oxide cement showed frequent premature decementation after thermocycling (mean: 14 N with 3-mm AH; 28 N with 5-mm AH). Both semi-permanent methacrylate-based cements ranked between the other cements (mean: 31 N/37 N for 3-mm AH; 120 N/72 N for 5-mm AH). Statistically significant differences were found between all cements (ANOVA P < .001). The abutment heights differed significantly for all cements (P < .005) except for the temporary zinc-oxide cement. Methacrylate-based cements were the most reliable cements for semi-permanent mounting of zirconia crowns on titanium abutments. They provide sufficient retention to avoid unintended loosening and are weak enough to remove the crown without causing damage. [ABSTRACT FROM AUTHOR]

Purpose: To test the push-out force and marginal leakage of different screw hole-sealing methods in monolithic zirconia implant crowns.Materials and Methods: Ninety monolithic zirconia (Prettau, Zirkonzahn) specimens were milled with two different screw access hole designs: conventional smooth hole or threaded screw hole (for group PMMA-SC), and divided into five groups (n = 18) according to filling method: unbonded composite (UBC); bonded composite (BC); airborne-particle abrasion of screw hole and unbonded composite (ABR-UBC); airborne-particle abrasion of screw hole and bonded composite (ABR-BC); and PMMA screw plugs (PMMA-SC). Twelve specimens per group were subjected to static push-out force with a universal testing machine. Before testing, 6 specimens per group were stored in dry conditions, and 6 were kept in water storage (+37°C) for 7 days. For the remaining specimens (n = 6), cotton pellets were placed under the screw access hole fillings, and the specimens were immersed in 0.5% basic fuchsin solution for 2 weeks. Dye in cotton pellets was dissolved in 2 mL of water, and absorbances of the solutions were measured with a spectrophotometer at 465 nm. Data are reported as mean and SD. Statistical analysis was made using a generalized linear model with logarithmic transformation.Results: PMMA-SC specimens showed the highest push-out forces (P < .0001) and lowest fuchsin penetration (P = .009). Airborne-particle abrasion increased the push-out force and decreased the microleakage in composite groups. The storage conditions affected the results of both unbonded groups.Conclusion: The design and sealing method of the screw access hole affect push-out force and microleakage. [ABSTRACT FROM AUTHOR]

Copyright of Firat Universitesi Sağlik Bilimleri Tip Dergisi is the property of Firat Universitesiu, Saglik Bilimleri Enstitusu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background. As dental implants become a more popular treatment option for restoring missing teeth, it is significant for a dentist to understand patients' level of knowledge toward implants, to avoid potential miscommunication and unrealistic expectations. Objectives. To determine the knowledge level regarding dental implants among patients applying for prosthetic treatment. Materials and methods. The study was conducted among patients from the Department of Prosthetic Dentistry at Wroclaw Medical University, Poland. A questionnaire composed of 11 questions was distributed to 232 patients, of which 225 were qualified for the study. The chi-square test of independence (χ2) was used to analyze the association between parameters of interest and groups of patients. The strength of studied relationships was measured with Cramer's V. Results. Patients showed limited knowledge of implants. Of the respondents, 75.6% heard about dental implants; however, 40% considered the dental implant as a set of a screw with a fixed crown. The major concern was the high cost (69.4%), followed by the need for surgery (31.2%). The Internet was the most popular source of information. The source of treatment financing has a strong correlation to the willingness to undergo treatment. Conclusions. The study group demonstrated not a satisfactory extent of knowledge regarding dental implants. Dental professionals should make an effort to provide sufficient information to patients to avoid misunderstandings about the treatment. Measures should be taken to reduce the cost of the procedure and thus increase its availability. [ABSTRACT FROM AUTHOR]

Objective: The objective of this study was to evaluate the peri‐implant soft tissue and marginal bone loss (MBL) around implants with platform‐switching and internal conical connection placed at crestal and subcrestal levels in posterior areas. Materials and methods: Nineteen partially edentulous patients with at least two adjacent missing teeth in posterior areas unilaterally or bilaterally were included. Forty‐two implants were placed randomly at the crestal or subcrestal (1 mm) level in a split‐mouth design. Implant‐supported fixed dental prostheses with screw retention were delivered after 4 months of healing. Clinical and radiological measurements were performed at implant placement (T0), restoration delivery (T1), and 1‐year follow‐up after loading (T2). MBL was calculated as the change in distance from the implant‐abutment interface to the first radiographically visible bone‐implant contact. A repeated‐measures mixed ANOVA followed by a paired Student's t‐test with the Bonferroni correction was used for statistical analysis. p < 0.05 was considered statistically significant. Results: Eighteen patients with thirty‐eight implants completed the study at T2. The MBL was lower in the subcrestal group than in the crestal group (0.04 ± 0.08 vs. 0.17 ± 0.17 mm, p = 0.004). The peri‐implant probing depth (PD) was 2.31 ± 0.48 mm in the subcrestal group and 1.92 ± 0.43 mm in the crestal group; this difference was statistically significant (p = 0.002). Intragroup comparison showed no significant differences in MBL, or PD around the crestal group and subcrestal group from T1 to T2. Conclusion: After 1 year of functional loading, subcrestal placement of implants with platform‐switching and internal conical connection showed lower MBL and was associated with greater PD and peri‐implant soft tissue height than implants placed at the crestal level. [ABSTRACT FROM AUTHOR]

The key for the long-term success of dental implants is the mechanical stability of the implant and the abutment anchored in it. The conical connection between screwed dental implants and abutments has good mechanical stability. However, with long-term use of the dental restoration fixed on a dental implant in the oral cavity, mechanical deformation of the assembled abutment in the implant and loosening of the fixing screw often occur, which affects long-term functionality. To study these processes, static compression loading tests were performed with various conical angle connections (35°, 55°, 75° and 90°) using Grade 4 and 5 titanium implant materials. After loading the implant and abutment assemblies with up to 500 N, the resulting deformations in length and diameter as well as the reverse-torque of the fixing screw were measured. No significant differences were observed between the results when the tested implant and abutment material was either Grade 4 or 5. Additionally, dynamic compression tests were performed on Grade 4 samples with different conical angles (30°, 45° and 60°). The relative changes in length (strain) of the assembly were determined over 30,000 cycles due to force varying periodically between 100 and 400 N. The reverse torques were also measured after the dynamic loading. The static and dynamic compression tests showed the same trend for different cone angles. Impression of the abutment into the dental implant was observed for lower conical angle connections. On the other hand, lower strain values were observed at larger conical angles. The reverse torque values of the fixing screws were only the half of the forward torque in case of lower conical angles, while high stability was observed with the larger conical angle connections (~ 20-30% reduction in torque). In summary, it is recommended to use a higher angle of the conical connection in order to avoid larger deformations in the lengths and diameters of the assembled implant and abutment system, as well as a significant reduction in the torque of the fixing screw. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the feasibility and effectiveness of using a suture-free titanium screw in repositioning anterior disc displacement without reduction (ADDwoR) of the temporomandibular joint (TMJ). Methods: A consecutive sample of twelve patients (fifteen joints) was included in this study. All patients were diagnosed with ADDwoR and showed limited mouth opening or temporomandibular joint pain symptoms. Suture-free titanium screw was placed in the condyle directly following the disc repositioning. Pre- and postoperative evaluation parameters include operation time, the visual analogue scale for pain (VAS), lateral excursion movements (LEM), maximum interincisal opening (MIO), and disc length and position on MRI. In addition, the mandibular condyle height was also measured. Statistical significance was considered when p < 0.05. Results: The unilateral operation time was 58.54 ± 5.43 min; during the 6-month period after the operation, the VAS values decreased from 87 ± 6.34 to 14.08 ± 6.65. The MIO increased from 30.07 ± 4.73 to 39.89 ± 1.69 mm (p = 0.01). The TMJ disc length was prolonged from 8.23 ± 1.12 to 11.51 ± 1.29 mm. The condyles showed significant remodeling, and the height of the condyle increased from 18.24 ± 4.12 increase to 19.6 ± 4.31 mm. The LEM was increased from 5.27 ± 0.51 to 6.36 ± 0.62 mm. The MRI images showed the stability of the disc in position during the opening and closing of the mouth. The TMJ disc position was stable during the follow-up period. Conclusion: Anteriorly displaced articular disc can be repositioned by a suture-free titanium screw strategy. This technique is an alternative method to address ADDwoR. [ABSTRACT FROM AUTHOR]

Copyright of Clinical Orthodontics is the property of Dental Press International and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: This study aimed to analyze the clinical outcome and complications of narrow-diameter dental implants (NDIs) (diameter ≤3.5 mm). Methods: The 274 NDIs that met the selection criteria from 2013 to 2018 were included in the retrospective study, and the survival rates (SVR) were compared. Mechanical complications included screw loosening and fractures of the implant components, such as the implant fixture, abutment, and prosthesis. In addition, marginal bone loss (MBL) was measured immediately after surgery and 1 year after loading. Results: The 3-year cumulative SVR was 92.4%. Nineteen fixtures failed during the follow-up. The failure rate was significantly higher (OR=4.573, p<0.05) in smokers and was significantly higher in osteoporosis patients (OR=3.420, p<0.05). The vertical and horizontal values of MBL were 0.33±0.32 mm and 0.18±0.17 mm, respectively. Mechanical complications included screw loosening (5.5%) and porcelain fracture (2.2%), but no fractures of the fixture or components were observed. The choice of titanium and zirconium (TiZr) alloy implant was significantly more frequent in the posterior region. Bone graft was significantly more frequently done in the anterior region. Conclusions: According to the high SVR and stability of NDIs, the findings of the study suggest that NDIs may be a replacement for regular diameter dental implants (RDIs) and the use of TiZr alloy could extend the indication of NDIs. In the esthetic area, contour augmentation may be a reason for increasing the frequency of bone grafts. [ABSTRACT FROM AUTHOR]

The placement of dental screw implants typically involves the use of rotary techniques and drills to create a bone bed. This study explores the potential benefits of combining this method with an Er:YAG laser. Split osteotomies were performed on 10 jaws of euthanized domestic pigs (Sus scrofa domestica), with 12 mandibular implant osteotomies in each jaw, divided into 4 groups. In order to make a comprehensive assessment of the effect of Er:YAG lasers, histomorphological techniques were used to measure the reduction in amorphous layer thickness after Er:YAG laser treatment, both with and without the placement of dental screw implants from different manufacturers. Following bone decalcification and staining, the thickness of the amorphous layer was measured in four groups: Group A—osteotomy performed without Er:YAG laser treatment—had amorphous layer thicknesses ranging from 21.813 to 222.13 µm; Group B—osteotomy performed with Er:YAG laser treatment—had amorphous layer thicknesses ranging from 6.08 to 64.64 µm; Group C—an implant placed in the bone without laser treatment—had amorphous layer thicknesses of 5.90 to 54.52 µm; and Group D—an implant placed after bone treatment with Er:YAG laser—had amorphous layer thicknesses of 1.29 to 7.98 µm. The examination and photomicrodocumentation was performed using a LEICA DM1000 LED microscope (Germany) and LAS V 4.8 software (Leica Application Suite V4, Leica Microsystems, Germany). When comparing group A to group B and group C to D, statistically significant differences were indicated (p-value = 0.000, p < 0.05). The study demonstrates the synergistic effects and the possibility of integrating lasers into the conventional implantation protocol. By applying our own method of biomodification, the smear layer formed during rotary osteotomy can be reduced using Er:YAG lasers. This reduction leads to a narrower peri-implant space and improved bone-to-implant contact, facilitating accelerated osseointegration. [ABSTRACT FROM AUTHOR]

Purpose: To examine the effect of tightening and loosening the dental implant screw on implant osseointegration in an elderly rat model.Materials and Methods: Titanium dental implants were inserted in the bilateral tibiae of 34 elderly Wistar rats (1 year and 3 months old). Rats were randomly divided into five groups: control (no loading); immediate loading (IL) (vertical load [3 Hz for 15 minutes/day] immediately after implantation); early loading (EL) (load started on postoperative day 7); five times abutment removal (R5) (tightening and loosening of the abutment screw once per day for 5 days each week); and two times abutment screw removal (R2) (tightening and loosening of the abutment screw once per day for 2 days each week). After 4 weeks, the rats were euthanized, and the bone structure surrounding the dental implants was evaluated using microcomputed tomography analysis.Results: Osseointegration failed more frequently in the EL, R2, and R5 groups than in the control and IL groups (P = .06). The EL, R2, and R5 groups also tended to have lower relative gray values than the control and IL groups.Conclusion: Tightening and loosening the abutment screw might negatively affect dental implant osseointegration in the early healing stage in older adults. [ABSTRACT FROM AUTHOR]

Purpose: To assess the success rates of cone beam computed tomography (CBCT) in identifying the locations and directions of abutment screw access holes (ASAHs) in metal-ceramic and all-ceramic implant restorations.Materials and Methods: Thirty-two implants were inserted into four clear acrylic casts. Metal-ceramic and all-ceramic crowns were placed on the inserted implants in two successive tasks. A maxillofacial radiologist determined the locations and angles of the ASAHs based on the CBCT images that were taken from the casts. Locations obtained from the CBCT images were carefully transferred to the crowns as access points. A prosthodontist pierced the crowns along the proposed access points and in the direction determined based on the CBCT images. Proper crown removal was considered to be the mark of success of CBCT in detecting ASAH location and direction. Fisher exact and chi-square tests were used to compare the results between the two types of restoration.Results: Success rates of CBCT for defining ASAH location and direction were, respectively, 96.9% and 93.8% in metal-ceramic restorations and 78.1% and 59.4% in all-ceramic restorations. There were no significant differences between the two restoration types regarding the detection of location in either molar (P = .333) or premolar (P = .226) crowns. Abutment angle did not affect the success rate of CBCT in determining ASAH location or direction in metal-ceramic restorations.Conclusion: CBCT images define the locations and directions of ASAHs in metal-ceramic restorations more reliably than in all-ceramic restorations. In contrast to the metal-ceramic crowns, the success rate of CBCT in all-ceramic crowns is more dependent on abutment angle and crown morphology. [ABSTRACT FROM AUTHOR]

Purpose: To assess the effect of extraoral polishing of the crown-abutment interface on the marginal fit of implant-supported screw- and cement-retained prostheses (SCRPs).Materials and Methods: In 31 patients, the marginal gap of an SCRP was measured using a stereomicroscope before and after polishing of the crown-abutment interface, and the paired data were compared.Results: The marginal gap was significantly decreased after surface polishing regardless of the prosthesis material (P < .001).Conclusion: Extraoral polishing of the crown-abutment interface could improve the marginal fit of SCRPs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 (t2 = 0.40, I2 = 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. [ABSTRACT FROM AUTHOR]

This in vitro study evaluated the effectiveness of a sealing agent on vertical misfit of the implant-abutment interface in an external hexagon implant system before and after mechanical cyclic loading. Effects on preload maintenance of retaining screws after mechanical cycling were also assessed. Materials and Methods: External hexagon implant systems were divided into two groups (n = 12) according to the presence of an anaerobic sealing gel (control group—no sealing gel; experimental group—sealing gel applied). A prefabricated UCLA abutment was attached to the external hexagon implant with a digital torque wrench in accordance with the recommendations of the manufacturer. Specimens were tested through mechanical cyclic loading (1 × 106 cycles, 2 Hz, and 130 N). Vertical misfit of the implant-abutment interface was analyzed using a stereomicroscope, and reverse torque values were obtained using a digital wrench. Misfit and reverse torque data were measured and analyzed via analysis of variance (ANOVA) and the Tukey least significant difference test (α = .05). Results: The sealing gel promoted lower vertical misfit values in the test group after mechanical cycling compared with before cycling (P = .009). The control group showed lower reverse torque values for retaining screws compared with the initial torque after mechanical cyclic loading (P < .0001). However, sealing gel application promoted higher reverse torque values in the test group postcycling (P = .0003). Conclusion: Anaerobic sealing agent application improved vertical misfit of the implant-abutment interface and preload maintenance of screw-retained implant-supported prostheses post–mechanical cycling. [ABSTRACT FROM AUTHOR]

To evaluate the resistance to fracture in cantilevered fixed dental prostheses (cFDPs) of single implant-supported zirconia cantilevers in the anterior region. Materials and Methods: Thirty-two cemented and solely screw-retained cFDPs consisting of an implant-supported crown replacing the central incisor and an attached cantilever unit in the position of the lateral incisor in the maxilla were constructed by computer-aided design (CAD) and machined by computer-aided manufacturing (CAM). For the cemented solution, a cFDP was designed on top of a customized abutment luted to an adhesive base. For screw-retained cFDPs, abutment, cement gap, and restoration of the cementable design were combined. All cFDPs were veneered manually on the facial side. Half of the samples underwent artificial aging (thermocycling and chewing simulation) before fracture tests were conducted with loads applied to the pontic either parallel to the implant axis (axial loading on the pontic) or tilted lingually by α = 45 degrees (oblique loading on the pontic). Thus, there were eight groups differing in cFDP design, artificial aging, and load application (n = 8/group). If fracture (Fu,total) occurred within the implant components, the adhesive base was replaced by a cast CoCr base, and the cFDP’s fracture resistance (Fu,cFDP) was also determined. Using statistical analyses (SPSS 24, IBM), factors affecting fracture resistance were identified. Results: Fu,total was mainly correlated to screw fractures and therefore not affected by cFDP design. Oblique loading on the pontic (Fu,total = 231 N – 352 N), however, led to a significant (P < .001) decrease in ultimate load compared with axial loading on the pontic (Fu,total = 611 N – 815 N). In relation to Fu,total, Fu,cFDP was approximately twice as high for both loading conditions. Conclusion: When relating the results to maximum occlusal forces exerted in the maxillary anterior region, single implant-supported cFDPs can be a viable restorative treatment option. [ABSTRACT FROM AUTHOR]

Purpose: To apply finite element analysis (FEA) to investigate the stress distribution in a 4-mm-high ultrashort implant when supporting crowns of different heights in order to test the possibility of using this implant unitarily in the posterior edentulous mandible.Materials and Methods: Three models of atrophic mandibles were created (M1, M2, and M3). Each model contained a 4-mm-length implant of a titanium-zirconium alloy, screw-type with internal connection, supporting nonsplinted screwed-in crowns of 10, 12.5, and 15 mm in height. Axial and oblique loads were simulated in the three model crowns.Results: In an oblique load, the stress tended to be concentrated in the lingual region. In the qualitative results of the axial load, peaks of tension occurred in the lower angle between the inner groove and the inner conical portion of the implant. Regarding the differences in crown height, the 15-mm height produced a higher stress peak due to the lever effect of the crown under an oblique load.Conclusion: Within the limits of this study, the results suggest the possibility of using single crowns of proposed heights with unitary ultrashort implants installed in the posterior edentulous mandible, so long as there is no oblique load on the crown. [ABSTRACT FROM AUTHOR]

Background and Objective: Loosening of abutment screws in dental implants is a mechanical complication that affects prosthetic treatments and hence, patient satisfaction. Blood contamination of abutment screws may play a role in this phenomenon. However, only limited research attention has been given to this issue. In the present study, we determined the effect of blood contamination and decontamination protocol on the reverse torque value (RTV) of abutment screws. Materials and Methods: A questionnaire-based survey was sent to 210 implantologists requesting feedback on their attitude to the blood contamination issue and the decontamination protocols used. The survey responses were used in a selection of the decontamination solutions that were used in the subsequent in vitro study on the effects of blood decontamination protocol on the RTV of abutment screws. Thus, three study groups were used (n = 20 abutment screws in each group): Group 1 (control group; blood-contaminated screws); Group 2 (screws decontaminated with 5.25% sodium hypochlorite (NaOCl) solution); and Group 3 (screws decontaminated with normal saline solution (0.9%)). Then, each of the connections were subjected to thermocycling, and RTVs of the screw were measured using a digital torque meter. Intragroup and intergroup RTVs were analyzed for significance using analysis of variance (ANOVA) and Tukey's honestly significant difference (HSD) tests. Results: 48% of the implantologists responded to the survey; 80% of them were concerned with blood contamination in the implant connection, especially before abutment loading and 85% of them used either chlorhexidine solution or normal saline solution as the decontamination agent. The mean RTV for Group 2 screws (30.27 ± 2.8 N.cm) was significantly greater than that for Group 3 screws (26.02 ± 1.99 N.cm) which, in turn, was significantly greater than that for Group 1 screws (23.64 ± 1.84 N.cm). Conclusion: Decontamination of blood-covered connections using 5.25% NaOCl solution or normal saline solution restores the RTV of abutment screws. This finding may have clinical relevance in that the decontaminated screws may contribute to the low incidence of screw loosening and, ultimately, improved patient satisfaction. [ABSTRACT FROM AUTHOR]

Robotic assistance can help in physically guiding the drilling trajectory during zygomatic implant positioning. A new robot-assisted strategy for a flapless zygomatic implant placement protocol is reported here. In this protocol, a preoperative computed tomography scan is used to plan the surgical path. After surface registration, the ROSA robot (Zimmer Biomet Robotics) guides several steps, which are performed with shared control. The surgeon performs the drilling and tapping, guided by the robotic arm, which is positioned according to the planned trajectory. Placement of the zygomatic implant is done manually. Immediate intraoperative 3D verification is performed by cone beam computed tomography (flat-panel detector, Medtronic O-arm II). Four zygomatic implants were placed in the case patient according to the flapless protocol, with a mean vector error of 1.78 mm (range 0.52–4.70 mm). A screw-retained temporary prosthesis was placed on the same day. No significant complications were observed. The application of this robot-assisted surgical protocol, which guarantees a very high degree of precision, may reduce inaccuracies in the positioning of zygomatic implants that could deviate from the surgeon's plan. This appears to be a potentially safe flapless surgery technique. Drill slipping on the crest or on the maxillary wall is the main source of error in this procedure, emphasizing the usefulness of the assisted surgical guidance with haptic feedback. [ABSTRACT FROM AUTHOR]

Aim and Objective: The aim of the study was to compare the full-depth bone thickness and the cortical bone thickness in the infrazygomatic crest (IZC) region above the mesiobuccal (MB) root of maxillary first molar and second molar and thus find the ideal site for the placement of IZC screw. Materials and Methods: Pretreatment cone-beam computed tomography images of 30 orthodontic patients were collected and IZC bone thickness and cortical bone thickness were measured above the MB root of maxillary first and second molar at an angle of 70° to the molar occlusal plane. Measurements were done on both right and left sides. Independent sample t test was done to compare the bone thickness between the right and left sides and also to compare the bone thickness above the first and the second molar. Results: Mean bone thickness at the IZC region of 5.48 ± 2.2 mm and 7.78 ± 2.35 mm and a cortical bone thickness of 2.24 ± 0.46 mm and 2.13 ± 0.46 mm was obtained above the MB root of maxillary first molar and second molar, respectively. IZC bone thickness was significantly higher above the second molar than above the first molar (P <.001), whereas there was no significant difference in the cortical bone thickness measured on both the sites (P =.22). Conclusion: Significantly higher IZC bone thickness was noted above the MB root of the maxillary second molar, which may ensure better stability and safety of the miniscrew. [ABSTRACT FROM AUTHOR]

Introduction: Management of mutilated cases is challenging, and adult patients often require orthodontic correction of occlusion before prosthetic replacement of missing teeth. Objective: To highlight the novel, simple, hygienic, and efficient miniscrew-supported Beta titanium molybdenum alloy (TMA) cantilever spring for uprighting severe mesially tipped molars for interdisciplinary treatment. Diagnosis and Treatment: A 23-year-old male patient presented with skeletal Class I relation, average growth pattern, Class II Division 1 malocclusion with dentoalveolar collapse, crowding, multiple missing, supraerupted teeth, and severe mesially tipped mandibular third molars. MBT appliance with 0.022˝ slot was used to achieve the objectives. 38 and 48 were uprighted and protracted with miniscrew implant-supported TMA cantilever springs to substitute 37 and 47. Mild intrusion of maxillary posterior teeth was done with acrylic bite blocks and transpalatal arch (TPA), followed by prosthetic replacement of missing teeth. Results: The patient had a consonant smile arc and a pleasing soft tissue profile. 38 and 48 were uprighted and protracted with good vertical control, and the mesial pockets were eliminated. 17 and 27 were intruded, and group function occlusion was established. Class I canine relationship, normal overjet, and overbite were achieved. Conclusion: Miniscrew supported TMA cantilevers are efficient for uprighting of severely tipped 38 and 48 without extrusion, unlike the conventional mechanics. 18, 28, 38 and 48 with good root forms can be protracted and substituted as 17, 27, 37 and 47 respectively to minimize or eliminate prosthetic rehabilitation. [ABSTRACT FROM AUTHOR]

The implementation of CAD-CAM systems in dentistry has significantly influenced the evolution of dental implantology and implant-supported prosthetics within the past three decades. Implant-supported prostheses are comfortable and aesthetic. The prosthetic abutment has also faced a rapid design evolution, from the individualization of standard stock abutments offered by various manufacturers to a modern customization process using CAD-CAM technology. This paper presents a comparative study between 20 dental custom CAD-CAM implant abutments and 20 dental implant stock abutments, based on a set of measurements performed on the digital casts obtained from 24 cases of prosthetic rehabilitation on implants. The statistical analysis (Mann–Whitney U test) revealed significant differences between these two types of abutments: the incisal margin line diameter dimensions for custom abutments were significantly improved compared to standard abutments at the cervical level (U = 343.00, z = 3.868, p < 0.0005) and the incisal/occlusal level (U = 352.00, z = 4.112, p < 0.0005), while the inclination angle of the custom abutments relative to the 0-axis was significantly smaller than that of standard abutments (U = 115.50, z = −2.286, p = 0.022). The use of custom abutments leads to an increase in the final size of the abutment, an improvement in the retention of the prosthetic work, and reduces the angulation of the abutment in relation to the implant axis, thus decreasing the risk of unscrewing or fracturing the dental screw. [ABSTRACT FROM AUTHOR]

Background: Tracheobronchial foreign body is uncommon in adults. Among foreign body aspirations, tooth and dental prosthesis aspiration is a very rare condition. In the literature, dental aspiration is generally found as a case report and there is no single-center case series. In this study, we aimed to present our clinical experience in 15 cases with tooth and dental prosthesis aspiration. Methods: Data from 693 patients who presented to our hospital for foreign body aspiration between the years 2006 and 2022 were analyzed retrospectively. Fifteen cases who aspirated tooth and dental prostheses as foreign bodies were included in our study. Results: Foreign bodies were removed by rigid bronchoscopy in 12 (80%) cases and fiberoptic bronchoscopy in 2 (13.3%) cases. In one of our cases, foreign body was expected with cough.When evaluated in terms of foreign body, partial upper anterior tooth prosthesis in 5 (33.3%) cases, partial anterior lower tooth prosthesis in 2 (13.3%) cases, dental implant screw in 2 (13.3%) cases, lower molar crown in 1 (6.6%) case, lower jaw bridge prosthesis in 1(6.6%) case, upper jaw bridge prosthesis in 1(6.6%) case, broken tooth fragment in 1(6.6%) case, upper molar tooth crown coating in 1(6.6%) case and upper lateral incisor tooth in 1(6.6%) case were observed. Conclusion: Dental aspirations can also occur in healthy adults. Anamnesis is the most important factor in diagnosis and diagnostic bronchoscopic procedures should be performed in cases where adequate anamnesis cannot be obtained. [ABSTRACT FROM AUTHOR]

The objective assigned to this study is to develop an antiseptic solution based on the ethanolic extract of the leaves of walnut (Juglans regia L.) and to evaluate the antibiofilm potential in vitro growth strains of staphylococci implicated in osteoarticular infections on the material (OAMI) in postoperative orthopedic surgery. The ethanolic extract of Juglans regia L. has been incorporated as an antimicrobial active principle in the formulation of the antiseptic solution 2%. Fourteen strains of Staphylococcus aureus were collected from the pus of postoperative wounds, from subjects suffering from a bone fracture, benefiting from a prosthesis and/or osteosynthesis material (external fixator, screw, nail, plate screwed). The Microtiter plate method was used to assess the ability of the pathogenic strains collected to produce the biofilm. The antibiofilm potential of the antiseptic solution 2% was achieved by the liquid dilution technique for the determination of the minimum inhibitory concentration of biofilm (CMIB). CMIB demonstrated a remarkable antibiofilm effect. A CMIB measured at 6.25% (v/v) showed a degree of antibiofilm sensitivity effective in vitro on 92.86% of strains. Faced with the effectiveness of the antiseptic solution 2% on the germs incriminated in OAMI, its use as a natural product without adverse effects for local care and postsurgical skin disinfection seems promising in the fight against infections. [ABSTRACT FROM AUTHOR]

Background. Tightening and loosening of the prosthetic components of the implant are carried out with various screw designs. This study compared the rate of deformation of the abutment screw in two hexagonal and star screw head designs after consecutive tightening and loosening. Methods. In this study, two fixtures were mounted vertically in die stone blocks using a surveyor. Then the corresponding abutment (with a diameter of 4.5 mm and a gingival height of 2 mm; Dio-SM and Dio-UF system) was mounted on each fixture. In each fixture, six abutment screws from each manufacturer were used (12 abutment screws in total). The abutment screw head of the Dio-UF system is hexagonal, and the abutment screw head of the Dio-SM system is star-shaped. The samples were examined under a stereomicroscope (Nikon C-DS) at a magnification of × 50. The image of each abutment screw head (6 abutment screws in each group) was prepared before the procedural steps and after 5, 10, and 15 times of tightening and loosening with 25-Ncm torque using a stereomicroscope. Then the differences in the surface areas of consecutive specimens (0, 5, 10, and 15 consecutive tightening and loosening rounds) between hexagonal and star-shaped abutment screws were calculated. The study results were reported via descriptive statistical methods (mean ± standard deviation). Statistical analysis was performed using SPSS 24, and the significance level was defined at P < 0.05. Results. Increasing the number of tightening and loosening rounds increased the screw head surface area in both hexagonal and star shapes. At all stages, the changes in the star-shaped screw head were greater than in the hexagonal screw. These changes were statistically significant at all stages (P < 0.05). In addition, there was a statistically significant difference between the area values and the number of tightening and loosening rounds separately in both screw types (P < 0.001). Also, the surface areas of the head of both screws in all tightening and loosening rounds were significantly different (P < 0.001). Conclusion. Increasing the number of tightening and loosening rounds increased the screw head surface area in both hexagonal and star-shaped geometrical forms. Also, the extent of area changes at all stages in star-shaped screw heads was greater than in hexagonal screws. [ABSTRACT FROM AUTHOR]

Purpose: To assess the influence of a screw access hole (SAH) and mechanical cycling on the fracture load of implant-supported crowns (ISCs) manufactured with screw-retained (s) or cement-retained (c) abutments with either metal (M) or zirconia (Z) infrastructure.Materials and Methods: Six groups of restorations were made based on type of infrastructure (M or Z), fixation (s or c), and whether they underwent aging (a) with mechanical cycling: Zc, Zs, Zsa, Mc, Ms, and Msa. All ISCs were porcelain veneered and tested for compression to failure in distilled water (37°C) using a universal testing machine. ISCs from groups Zsa and Msa were mechanically cycled (106 cycles; 2 Hz, 100 N) in distilled water before compressive testing. Fractographic principles were followed to assess the fracture surfaces. The fracture load data were statistically analyzed using one-way analysis of variance and Tukey test (α = .05). The relationships between experimental group and failure mode were analyzed using chi-square test (α = .05).Results: Regardless of the infrastructure material, cement-retained ISCs (Zc and Mc) showed higher fracture load values than screw-retained ISCs (Zs, Zsa, Ms, and Msa) (P < .001), which were statistically similar to each other (P > .05). Aging had no effect on the fracture load of ISCs. There was a significant relationship between failure mode and experimental group (P < .001). Catastrophic fractures were found only in Zc and Zs. All metal-based ISCs failed from chipping reaching the metal infrastructure.Conclusion: Cement-retained ISCs showed higher fracture resistance than screw-retained prostheses. No catastrophic failures were found for metal-based ISCs. Aging did not affect the fracture load, but did affect the failure mode of ISCs. [ABSTRACT FROM AUTHOR]

The computer-assisted design/computer-assisted manufactured compound prosthesis involves designing and milling a cement-retained prosthesis over milled titanium bars. In the presented clinical case report, a diagnostic wax pattern was made to assess esthetics, contours, and occlusion. A total of eight maxillary root-form implants were restored by following the combined prosthesis design concept. The mandibular arch was restored with a screwretained implant-supported zirconia fixed prosthesis. A milled polymethyl methacrylate (PMMA) maxillary interim prosthesis was fabricated to intraorally confirm the diagnostic wax pattern. The interim PMMA prosthesis was then scanned, and three screw-retained titanium milled bars were designed that provided the substructure of the definitive restoration. A cement-retained milled zirconia prosthesis was then designed and fabricated. The zirconia prosthesis provided the superstructure of the definitive complete-arch restoration. After confirming esthetics, phonetics, occlusion, and accessibility for oral hygiene, the superstructure was cemented with temporary cement to enable retrievability. [ABSTRACT FROM AUTHOR]

Titanium implants in the head have been used widely for decades. Dental implants as well as titanium plates, screws, and mesh have been an integral part of dental and maxillofacial surgery. In the nose, titanium implants were started in 2003. Their purpose is to increase structure and stiffness to nasal cartilages widening the airway. This overview describes the use of titanium implants in the various locations in the nose. We concentrate on three locations: Breathe Implants on the upper lateral cartilage to widen the internal nasal valve, modified breathe implants in the lower lateral nasal wall fixed to the piriform aperture as batten grafts to widen the external nasal valve, and flattened breathe implants as titanium septum plates to straighten and strengthen the nasal septum. [ABSTRACT FROM AUTHOR]

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The objective of this study was to present a novel procedure for cortical bone repositioning (CBR) that maintains a secure space under the periosteum by replacement of the lateral cortex via fixation, employing titanium screws. Seven systemically healthy patients presenting with horizontal alveolar bone defects in radiographs and CT images were enrolled for CBR technique for horizontal alveolar bone augmentation. A lateral cortical bone block was cut in the defects and freed from the original bony surface. A screw was inserted into the block, and the block was placed laterally to allow fixation. The block was checked for adequate stability, and the flap was closed after creation of periosteal releasing incisions to ensure tension-free closure. There were no complications, and 16 implants were placed uneventfully. Preoperative bone width in the defect area was 3.28 mm; the postoperative 4-month bone width in the same area was 6.46 mm. The mean implant stability quotient (ISQ) at placement was 68. At the secondary operation for changing to a healing abutment, the mean ISQ was 72. All patients were functionally and esthetically rehabilitated with implant-supported dentures. CBR technique is a simple procedure without the use of any biomaterials or devices. The main advantage of this technique in comparison to autogenous grafts is the lack of donor site issues. This technique has the possibility of inducing the patient's regenerative ability for bone healing. [ABSTRACT FROM AUTHOR]

The aim of this study was to document the performance of a novel technique (OnlyOne), involving immediate restoration of postextraction implants supporting a partial or full-arch restoration. A retrospective analysis of patients with at least 3 years of follow-up was performed. Implants were tilted mesiodistally and vestibulopalatally according to the available bone. Prosthetically guided definitive abutments were connected at surgery and never disconnected. Anorganic bovine bone grafting was done to preserve the buccal bone and the ridge contour. Patients received a screw-retained provisional prosthesis within 24 hours of surgery and a final screw-retained prosthesis within 1 year. Prostheses emerged from natural soft tissue. Clinical and radiographic evaluation was routinely performed. A total of 70 patients received 153 implants in fresh extraction sockets. The mean follow-up was 38.0 ± 3.0 months (range 36 to 51 months). One implant failed at the 3-year follow-up. Implant survival was 99.3%. Marginal bone level change averaged -0.68 ± 1.2 mm at the last radiographic control. Immediate placement and restoration of implants designed for high primary stability with a definitive abutment placed at surgery and final screw-retained prosthesis with no artificial gingiva is a viable procedure with excellent medium-term outcomes. [ABSTRACT FROM AUTHOR]

Purpose: To compare the clinical outcomes of screw-retained vs cemented single crowns supported by customized zirconia abutments on implants.Materials and Methods: Thirty-two patients received implant-supported (Regular Neck, Tissue-Level, Straumann AG), single-tooth restorations with customized zirconia abutments in the anterior areas. Participants were randomly assigned to the screw-retained (full-crown abutment [FCA]) group or the cemented (zirconia crown [ZrC]) group and followed up over a 10-year period. Prosthetic and biologic complications, marginal bone level (MBL), mucosal recession, and pink and white esthetic scores (PES and WES, respectively) were evaluated.Results and Conclusion: There were no implant failures during the study period; after 10 years, 94% of crowns were functional. Prosthetic complications were recorded in both groups (three FCA and two ZrC), and no significant difference was found (P = .65). Two cases of mucositis were recorded, one in each group. Esthetic outcomes were assessed using PES and WES scores. MBL was 0.95 mm in the ZrC group and 0.82 mm in the FCA group, with no significant difference between groups. These encouraging preliminary results need to be confirmed with long-term follow-up on larger study samples. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effectiveness of precise threedimensional hydroxyapatite printed micro- and macrochannel devices for alveolar ridge augmentation in a canine model. All grafts induced minimal inflammatory and fibrotic reactions. Examination of undecalcified sections revealed that both types of grafts demonstrated bone ingrowth. The majority of the bone growth into the block graft was into the channels, though a portion grew directly into the construct in the form of small bony spicules. In conclusion, bone ingrowth was readily demonstrated in the middle of the implanted printed devices. [ABSTRACT FROM AUTHOR]

Purpose: To describe the restorative treatment profiles of long-span (> three units), implant-supported dental prostheses (LIDPs) prescribed in 27 private practices in the state of Victoria, Australia, during the period from January 1, 2005, to December 31, 2009. The restorative treatment profiles of these prostheses refer to the framework/veneering materials, number of prosthetic units/supporting implants, location in the oral cavity, retention methods, and cantilever designs. LIDPs refer to implant-supported prostheses of fixed or removable design; namely, fixed partial dentures (IFPDs), fixed complete dentures (IFCDs), removable partial dentures (IRPDs), and complete overdentures (IODs).Materials and Methods: Private dental practitioners providing implant treatment in Victoria, Australia, were invited to enroll in this study, which was conducted through a dental practice-based research network (the eviDent Foundation). The enrolled practitioners' clinical records of the implant treatments provided during the specified period were accessed for data collection. Descriptive statistics, cross-tabulations, and linear mixed models were conducted for data analyses.Results: During the study period, 627 LIDPs were prescribed to 556 patients by 18 general dentists and 5 prosthodontists. LIDPs were more common in the maxilla than in the mandible except in the case of IODs. Of the fixed prostheses, 60% replaced missing teeth in more than one sextant, 33% in the anterior sextant, and 7% in the posterior sextant. The average number of prosthetic units per implant was higher in mandibular compared to maxillary IFPDs/IFCDs (2.5 vs 1.9, respectively, P < .001). Cantilever pontic(s) were present in 68% of IFCDs (more often in the mandible than in the maxilla) compared to 28% of IFPDs (use of cantilever pontics was about the same in the maxilla and mandible). Screw retention was the most commonly reported retention method in IFPDs/IFCDs (95%). Locator attachment was used for the majority of IRPDs/IODs (83%).Conclusion: The clinicians enrolled in this study preferred fixed over removable LIDPs for partially dentate and maxillary edentulous cases. For mandibular edentulous patients, IODs were prescribed more often than IFCDs. A retrievable retention design was favored for IFPDs/IFCDs. IFPDs were predominantly metal-ceramic, and metal-acrylic designs were more popular for IFCDs. [ABSTRACT FROM AUTHOR]

Purpose: To study the force used for tightening tapered one-piece prosthetic abutments and their influence on the removal torque value and stress level of the prosthetic abutment after cyclic loading. Materials and Methods: Fourteen implants and prosthetic abutments were divided into two groups (n = 7): G1, 20 Ncm; and G2, 32 Ncm (manufacturer recommended). A 20-mm T-shaped horizontal bar was adapted to the abutments. A 12-Hz cyclic loading was applied to the specimens in an electrodynamic testing system with the maximum number of cycles set to 106. Specimens were inclined by 15 degrees from the vertical axis, and a 5-mm off-center vertical load was applied to generate a combination of bending and torquing moments on the tapered connections. Progressive loads (from 164.85 to 362.85 N) were applied when the previous sample survived 106 cycles. The paired t test compared the screw removal torque with the initial tightening torque for each group (α = .05). A finite element analysis (FEA) of the mechanical testing analyzed the regions of stress concentration. Results: No specimens failed after 106 cyclic loadings. The mean screw removal torque for both groups was similar to the initial abutment torque value applied for each group (G1, 20.36 ± 8.73 Ncm; and G2, 35.61 ± 6.99 Ncm) (P > .05). FEA showed similar stress behavior for both groups in the study despite the different simulated screw preloads (G1: 200 N; G2: 320 N). The coronal region of the implant body presented the highest strain values in both groups. Conclusion: Tightening tapered one-piece prosthetic abutments at 20 and 32 Ncm maintains a stable connection after cyclic loading. The stresses generated by the different tightening forces during cyclic loading are highest at the coronal level of the connection. [ABSTRACT FROM AUTHOR]

Purpose: Screw-retained zirconia implant crowns with an internal titanium base have favorable mechanical properties compared with single-piece zirconia implant crowns; however, the screw-retained implant crowns require adequate bonding between the zirconia crown and the titanium base. This study measured the retention between a titanium base and a full-contour zirconia implant crown following different surface treatments of their bonded surfaces. Materials and Methods: Full-contour screw-retained zirconia implant crowns were fabricated to fit a titanium base. The crowns were bonded to the titanium bases following one of four treatment protocols (n = 15 per protocol group): no surface treatment (Control), 10-methacryloyloxydecyl dihydrogen phosphate (MDP) primer on the intaglio of crown and exterior of base (MDP), alumina airborne-particle abrasion of the intaglio of crown and exterior of base (Alu), and alumina airborne-particle abrasion and an MDP primer on the intaglio of crown and exterior of base (Alu+MDP). All crowns were bonded to the base with resin cement. Specimens were stored in water for 24 hours at 37°C and then thermocycled in water, with a temperature range of 5°C to 55°C, for 15,000 cycles with a 15-second dwell time. Crowns were separated from the titanium bases using a universal testing machine. The four treatment protocols were compared using one-way analysis of variance (ANOVA), followed by Tukey post hoc tests (P < .05). Sectioned specimens were examined with scanning electron microscopy (SEM). Results: Retention forces for Control (737.8 ± 148.9 N) and MDP (804.1 ± 114.5 N) were significantly greater than Alu+MDP (595.5 ± 122.2 N), which was significantly greater than Alu (428.2 ± 93.8 N). Visual inspection of the debonded specimens showed that the majority of the cement remnants were seen on the external surface of the titanium bases. Microscopic examination of the interface between the crown and the unaltered base shows that the cement gap is approximately 13 μm at the crest of the microgrooves and 50 μm within the channel of the microgrooves. After airborne-particle abrasion, the microgrooves became significantly dulled, and the cement gap increased to 27 to 40 μm at the crest and 55 to 58 μm in the channels. Conclusion: Airborne-particle abrasion of titanium bases that contain retentive microgrooves prior to bonding is contraindicated. Application of an MDP primer demonstrated limited improvement in the retention of the zirconia implant crowns. [ABSTRACT FROM AUTHOR]

Purpose: This review aimed to compile and enumerate all the factors described in the literature that may affect the decision to use either cemented or screw-retained restorations and to determine the relative weights of each factor by type of retention and prosthesis.Materials and Methods: The literature was reviewed, and the factors were classified as either determining (present in a clinical situation in which one of the retention mechanisms was clearly more suitable than the other) or conditioning (present in clinical situations in which one type of restoration was not clearly more advantageous than the other).Results: Three determining factors (esthetic outcome, retention, and biologic risk) and five conditioning factors (passive fit, fracture strength, occlusal area, complications, and retrievability) were identified.Conclusion: Although there is not a clearly better alternative for all clinical situations, determining factors in certain scenarios can render one of the two approaches more recommendable. For esthetic reasons, when the implant angle cannot be corrected to conceal the access hole, cementation is more suitable; however, screw retention is the better option when the occlusal space is under 6 mm or margins cannot be located supra- or equigingivally. In the absence of determining factors, the decision should be based on conditioning factors, which carry different weights depending on the type of prosthesis. [ABSTRACT FROM AUTHOR]

Bone resorption around implants is quite common, and the maturity and popularization of computer-aided design and computer-aided manufacturing (CAD/CAM) technology have made the use of aftermarket abutment screws more widespread. This study aimed to explore the biomechanical influence of these two common factors on the internal stress of an implant system using three-dimensional finite element analysis (3D FEA). The FEA results indicated that under the same loading conditions, the use of an aftermarket screw had the greatest impact on the screw itself among the three components of the implant system, while the maximum stress increased by 6.3% and 10.5% in the bone integrity and bone loss models, respectively. Moreover, the marginal bone loss models had the greatest impact on the implant fixture, with a maximum stress increase of 51.8% on average. Evidently, the influence of bone loss might be far greater than that of the aftermarket screw; however, any factor could be enough to cause clinical failure. Therefore, we should pay more attention to the maintenance of the long-term peri-implant marginal bone integrity. [ABSTRACT FROM AUTHOR]

For patients with existing implants in need of additional implant placement, the use of the existing implants for guide fixation seems to be a logical alternative. Current options for the fabrication of surgical guides involve creating surgical guides that are mucosa‐borne and/or retained by fixation pins. Since these existing techniques involve inherent inaccuracies, the fabrication of surgical guides that are screw‐retained at the implant‐ or abutment‐level would eliminate the introduction of those same fundamental inaccuracies. The purpose of the present technical report is to illustrate a step‐by‐step digitally planned guided implant placement protocol for terminal dentition patients with salvageable existing implants requiring full‐arch implant rehabilitation. The advantages of this protocol include enhancing the accuracy of guided implant placement with screw‐retention versus the traditional mucosa‐ or fixation pin support. Thus, this simplifies the transition from failing teeth to implants by ensuring that fixed provisionalization serves both functional and esthetic requirements. This protocol can also predictably reduce chairside time and adjustments at the surgical implant placement appointment. [ABSTRACT FROM AUTHOR]

Longevity of implant-supported fixed partial dentures (ISFPDs) may be associated with multiple clinical complications, irrespective of whether retention is achieved via screws or cement. While use of screws ensures ease of prosthesis retrievability and elimination of the inherently risky cementation process, more mechanical strains are induced in this design. A combined screw-retrievable and cement-retained ISFPD is designed to achieve the best passive fit and strain reduction while allowing complete excess cement removal and maintaining ease of retrievability. Moreover, this approach suggests better protection of the cement layer from oral environment degradation and offers scope for an alternative retention protocol. This paper outlines aspects of the clinical indications and fabrication of a screw-retrievable, cement-retained ISFPD. A diagnostic assessment method that provides tactile resistance guidance for selection is also proposed. [ABSTRACT FROM AUTHOR]

Objectives: To compare screw‐retained and cemented all‐ceramic implant‐supported single crowns regarding biological and technical outcomes over a 5‐year observation period. Materials and methods: In 44 patients, 44 two‐piece dental implants were placed in single‐tooth gaps in the esthetic zone. Patients randomly received a screw‐retained (SR) or cemented (CR) all‐ceramic single crown and were then re‐examined annually up to 5 years. Outcome measures included: clinical, biological, technical, and radiographic parameters. Data were statistically analyzed with Wilcoxon–Mann–Whitney, Wilcoxon, and Fisher's exact tests. Results: During the observation period, three patients (6.8%) were loss to follow‐up. Eight restorations (18.2%, CI (8.2%, 32.7%)) were lost due to technical (6 patients, 13.6% (CI (5.2%, 27.4%)), 2 CR and 4 SR group, intergroup p =.673; implants still present) or biological complications (2 patients, 4.5% (CI (0.6%, 16.5%)), only CR group, intergroup p =.201, both implants lost). This resulted in a survival rate of 81.2% (CI (65.9%, 90.1%)) on the restorative level (18 SR; 15 CR, 3 lost to follow‐up). At the 5‐year follow‐up, the median marginal bone levels were located slightly apical relative to the implant shoulder with 0.4 mm (0.5; 0.3) (SR) and 0.4 mm (0.8; 0.3) (CR) (intergroup p =.582). Cemented restorations demonstrated a significantly higher biological complication rate (36.8%, SR: 0.0%; intergroup p =.0022), as well as a significantly higher overall complication rate (68.4%, SR: 22.7%, intergroup p =.0049). All other outcomes did not differ significantly between the two groups (p >.05). Conclusions: All‐ceramic single‐tooth restorations on two‐piece dental implants resulted in a relatively low survival rate. Cemented restorations were associated with a higher biological and overall complication rate than screw‐retained restorations. [ABSTRACT FROM AUTHOR]

Purpose: Screw-retained implant crowns used as dental implants comprise a zirconia coping and titanium base bonded using resin cement. These devices are prone to debonding failures. This study investigated the bond characteristics of implant materials based on shear bond strength (SBS) and surface characteristics. Methods: Chemically pure (CP) titanium grade-4 (Ti), Ti-6Al-4V alloy (Ti-6Al-4V), and tetragonal polycrystalline zirconia (zirconia) were evaluated as adherent materials. Plates of each material were polished, primed for the respective resin cements, and cemented using either methyl methacrylate-based resin cement (Super-Bond) or composite-based resin cement (Panavia). The cemented samples were subjected to 10,000 thermocycles alternating between 5 and 55 °C, and the SBS were obtained before and after thermocycling. The sample surfaces were characterized based on surface observations, roughness, and free energy (SFE). Results: The SBSs of all materials bonded using Panavia were significantly compromised during thermocycling and reached zero. Although the SBSs of Ti and Ti-6Al-4V bonded using Super-Bond were not significantly affected by thermocycling, those of zirconia decreased significantly. The bond durability between zirconia and Super-Bond was improved via alumina air-abrasion, which caused no significant loss of SBS after thermocycling. Surface analyses of the air-abraded zirconia validated these results and confirmed that its surface roughness and SFE were significantly increased. Conclusion: The bond durability between resin cement and zirconia was lower than that between Ti and Ti-6Al-4V. The alumina air-abrasion pretreatment of zirconia improved the SFE and surface roughness, thereby enhancing bond durability. [ABSTRACT FROM AUTHOR]

Inserting a presurgically fabricated provisional restoration at the time of implant placement can be problematic if and when the provisional does not fit. The 3-dimensional position of the implant iii the mouth typically is not as critical as the long-axis rotational orientation of the implant, which is known as "timing." During implant placement, it is often desirable to have one of the implant's internal hexagon flats iii a specific rotational position (ie, timing) that enables the use of orientation-specific hexed abutments. Achieving timing with a high level of accuracy, however, is challenging. This article presents a proposed solution to this dilemma that eliminates any concern for implant timing during surgery by transferring the anti-rotation control from the implant's internal hex to the provisional restoration itself via the use of anti-rotational wing(s). [ABSTRACT FROM AUTHOR]