Enhancing precision and accuracy in fabricating complete arch screw retained implant prosthesis:Case report utilizing the Nexus iOS scan gauge system.

Achieving an accurate fit in a complete arch screw-retained implant prosthesis is paramount, regardless of whether analog or digital impressions are employed. In the context of complete arch implant prostheses, using intra-oral scanners has sparked significant debate. However, recent advancements in scanner technology, specialized scan gauges meticulously calibrated for precise recording, and the implementation of appropriate scanning techniques have substantially improved the precision and accuracy of digital records. The Nexus iOS scan gauge system represents a pioneering approach, seamlessly integrating these optimization strategies into a purely digital workflow to fabricate complete arch screw-retained implant prostheses in edentulous patients. This case report elucidates the fabrication process of a complete arch screw-retained implant prosthesis that exhibited remarkable fitting accuracy and streamlined the treatment process to a mere three appointments. The patient reported high satisfaction with the efficient timeline, aesthetic appeal, and functional performance of the prosthesis. A distinctive advantage of this technique is the notable reduction in treatment steps compared to traditional procedures.

Influence of Implant Location, Number, and Design in Ischemic Zone for Implant Prosthesis Success Rate: A Comparative Three-Dimensional Finite Element Analysis.

BACKGROUND: The performance of an implant-supported prosthesis depends on the implant type, number, implant location, and prosthesis design which is directly associated with the distribution of the occlusal forces during mastication. The purpose of the present study is to analyze with three-dimensional (3D) finite element comparative analysis, the influence of implant location, number, and prosthesis design in the mandibular posterior region where multiple posterior teeth replacement is indicated, which in turn is associated with the longevity or Implant success rate. MATERIAL AND METHODS: Mandibular posterior section, where 4 teeth are missing, based on the space available for implants and following the surgical guide instructions, a standard make four implants (1st and 2nd premolars {3.8 mm × 11.5 mm}, 1st and 2nd molar {5.1 mm × 11.5 mm}) were selected and with standardization for placement, 4 groups were created with different implant location, number and prosthesis design from the selected implants as model FM1, FM2, FM3, FM4. Finite element analysis was carried out using ANSYS software, version 14.5 (ANSYS Inc., Canonsburg, PA, USA) for assessment of stress, strain, and deformation around implant and bone. RESULTS: Maximum von Mises stress on vertical loading was highest for FM4 (139.55MPa) model (center of prosthesis on premolar and molar pontics) and lowest for FM3 (53.65MPa) model (on 2nd premolar pontic) with values in decreasing order as FM4 ˃ FM2 ˃ FM1 ˃ FM3. Maximum von Mises stress on oblique loading was highest at the distal of 1st molar implant pontic for FM2 (539.81MPa) and lowest at the 2nd premolar pontic for FM3 (352.48MPa) model with values as FM2˃FM1˃FM4˃FM3. Deformation for vertical and oblique loading was observed minimum at the buccal cusp and buccal crestal bone of 2nd premolar, 1st molar on FM3 model against highest deformation on buccal and lingual crestal bone, cuspal area of 2nd premolar, 1st molar implants. For oblique loading minimum deformation was seen for the 2nd premolar, 1st molar cuspal area in FM3, and maximum at the 2nd premolar region in FM1. CONCLUSION: Four single implants may be chosen if there is enough mesiodistal and buccolingual space to allow for a minimum inter-implant and inter-implant-tooth distance that can be maintained while putting the least amount of stress on the implants and bone. To reduce stress on the bone and implants, it is best to avoid long-span implant-supported prostheses when using fixed implant-supported prostheses.

A retrospective study of occlusal reconstruction in patients with old jaw fractures and dentition defects.

PURPOSE: This study evaluated the methods and clinical effects of multidisciplinary collaborative treatment for occlusal reconstruction in patients with old jaw fractures and dentition defects. METHODS: Patients with old jaw fractures and dentition defects who underwent occlusal reconstruction at the Third Affiliated Hospital of Air Force Military Medical University from January 2018 to December 2022 were enrolled. Clinical treatment was classified into 3 phases. In phase I, techniques such as orthognathic surgery, microsurgery, and distraction osteogenesis were employed to reconstruct the correct three-dimensional (3D) jaw position relationship. In phase II, bone augmentation and soft tissue management techniques were utilized to address insufficient alveolar bone mass and poor gingival soft tissue conditions. In phase III, implant-supported overdentures or fixed dentures were used for occlusal reconstruction. A summary of treatment methods, clinical efficacy evaluation, comparative analysis of imageological examinations, and satisfaction questionnaire survey were utilized to evaluate the therapeutic efficacy in patients with traumatic old jaw fractures and dentition defects. All data are summarized using the arithmetic mean and standard deviation and compared using independent sample t-tests. RESULTS: In 15 patients with old jaw fractures and dentition defects (an average age of 32 years, ranging from 18 to 53 years), there were 7 cases of malocclusion of single maxillary fracture, 6 of malocclusion of single mandible fracture, and 2 of malocclusion of both maxillary and mandible fractures. There were 5 patients with single maxillary dentition defects, 2 with single mandibular dentition defects, and 8 with both maxillary and mandibular dentition defects. To reconstruct the correct 3D jaw positional relationship, 5 patients underwent Le Fort I osteotomy of the maxilla, 3 underwent bilateral sagittal split ramus osteotomy of the mandible, 4 underwent open reduction and internal fixation for old jaw fractures, 3 underwent temporomandibular joint surgery, and 4 underwent distraction osteogenesis. All patients underwent jawbone augmentation, of whom 4 patients underwent a free composite vascularized bone flap (26.66%) and the remaining patients underwent local alveolar bone augmentation. Free gingival graft and connective tissue graft were the main methods for soft tissue augmentation (73.33%). The 15 patients received 81 implants, of whom 11 patients received implant-supported fixed dentures and 4 received implant-supported removable dentures. The survival rate of all implants was 93.82%. The final imageological examination of 15 patients confirmed that the malocclusion was corrected, and the clinical treatment ultimately achieved occlusal function reconstruction. The patient satisfaction questionnaire survey showed that they were satisfied with the efficacy, phonetics, aesthetics, and comfort after treatment. CONCLUSION: Occlusal reconstruction of old jaw fractures and dentition defects requires a phased sequential comprehensive treatment, consisting of 3D spatial jaw correction, alveolar bone augmentation and soft tissue augmentation, and implant-supported occlusal reconstruction, achieving satisfactory clinical therapeutic efficacy.

Technique for cementing screwmentable implant crowns to prevent misalignment.

The purpose of this article is to describe a technique to accurately cement implant crowns on an abutment extraorally and prevent misalignment that might change the desired position of the crown on the abutment when delivered. An implant-retained crown was tried-in and occlusal and interproximal contacts were adjusted for delivery. The cementation verification aid was fabricated using a polyvinylsiloxane bite registration material (Blu Mousse) to cement the crown onto the abutment extraorally to ensure proper alignment of the crown on the abutment. Cementation of the prosthesis occurred with no adjustments required to the interproximal or occlusal contacts during final delivery. This article provides a technique that aims to increase accuracy in the placement of the crown on the abutment when cementing screwmentable crowns.

Printed abutment model to limit residual cement: A dental technique.

Preventing retained cement around implant-retained crowns is crucial for the long-term health and success of the implant. Residual subgingival cement is strongly associated with peri-mucositis and can lead to peri-implantitis. This clinical technique utilizes a 3D printed model of a custom abutment to seat the implant crown on before cementing intra-orally to extrude excess cement. The technique aims to limit the amount of retained cement at the crown-abutment margin and also takes into consideration the cement space already designed into the crown-abutment complex.

Impact of color temperature and illuminance of ambient light conditions on the accuracy of complete-arch digital implant scans.

OBJECTIVE: The purpose of the present study was to assess the influence of color temperature and illuminance of ambient light on the accuracy of different intraoral scanners (IOSs) in complete-arch implant scans. METHODS: An edentulous model with six implants and scan bodies was digitized by using a laboratory scanner (DW-7-140; Dental Wings) to obtain a reference mesh. Fifteen scans were performed employing two intraoral scanners (Trios 4;3Shape A/S and i700; Medit Co) at two illuminances (500 and 1000 lux) and three color temperatures (3200, 4400, and 5600 K). Scanning accuracy was measured by using a 3D metrology software program (Geomagic Control X). Kruskal-Wallis, one-way ANOVA, and pairwise comparison tests were used to analyze the data (α = .05). RESULTS: Significant differences in trueness and precision values were found among the different IOSs under the same ambient lighting condition and among the different lighting conditions for a given IOS (p < .05) except for trueness in i700 groups (p > .05). CONCLUSIONS: The influence on the accuracy of color temperature and illuminance varied depending on the intraoral scanner. An optimal ambient scanning light condition was not found; this should be adjusted based on the specific IOS system used. 3200 K of ambient light influences the precision of i700 when performed at 1000 lux, decreasing the accuracy. The variation of color temperature at the same illuminance does not affect the scanning accuracy of TRIOS 4, which obtained better accuracy in all scans at 1000 lux.

A prospective multicenter clinical study on the efficiency of detachable ball- and spring-retained implant prosthesis.

PURPOSE: This prospective clinical study was conducted to evaluate the clinical usefulness of the freely detachable zirconia ball- and spring-retained implant prosthesis (BSRP) through a comparative analysis of screw- and cement-retained implant prosthesis (SCRP). MATERIALS AND METHODS: A multi-center, randomized, prospective clinical study evaluating the clinical usefulness of the detachable zirconia ball- and spring-retained implant prostheses was conducted. Sixty-four implant prostheses in 64 patients were examined. Periodic observational studies were conducted at 0, 3, 6, and 12 months after delivery of the implant prosthesis. Factors such as implant success rate, marginal bone resorption, periodontal pocket depth, plaque and bleeding index, and prosthetic complications were evaluated, respectively. RESULTS: During the 1-year observation period, all implants survived without functional problems and clinical mobility, showing a 100% implant success rate. Marginal bone resorption was significantly higher in the SCRP group than in the BSRP group only at the time of implant prosthesis delivery (P = .043). In all observation periods, periodontal pocket depth was slightly higher in the BSRP group than in the SCRP group, but there was no significant difference (P > .05). The modified plaque index (mPI) scores of both groups were moderate. Higher ratio of a score 2 in modified sulcus bleeding index (mBI) was observed in the BSRP group in the 6- and 12-months observation. CONCLUSION: Within the limitations of this study, the newly developed zirconia ball- and spring-retained implant prosthesis could be considered as an applicable and predictable treatment method along with the existing screw- and cement-retained prosthesis.

Evaluation of Prosthetic Outcomes and Patient Satisfaction With 3D-Printed Implant-Supported Fixed Prosthesis.

OBJECTIVES: The objectives of this study were to quantify the number and type of prosthetic complications associated with 3D-printed implant-supported fixed prostheses (3DISFP) and to evaluate patient satisfaction and oral health-related quality of life over a four-month period. METHODS:  Fifteen edentulous patients who underwent implant therapy were included in the study. Each patient received a 3D-printed prosthesis using OnX dental resin. Prosthetic complications were documented, and data from the 14-item Oral Health Impact Profile (OHIP) questionnaire were collected at two time points: at enrollment and during a four-month recall. RESULTS: During the four-month evaluation period, a total of nine complications were recorded, with three classified as catastrophic failures. Statistical analysis revealed statistically significant differences in OHIP scores between the preoperative and postoperative assessments (p<0.001). CONCLUSION: Within the limitations of this study, it can be concluded that utilizing 3D-printed prostheses with OnX resin represents a viable alternative for long-term implant-supported temporaries. The patients experienced a significant improvement in their oral health-related quality of life. These results suggest that 3D printing technology, combined with the use of OnX resin, holds promise in providing satisfactory clinical outcomes and enhanced patient satisfaction. However, it is important to acknowledge the limitations of this study, and further research is warranted to validate these findings and explore the long-term performance and durability of 3D-printed implant-supported fixed prostheses. This study contributes to the growing body of evidence supporting the effectiveness of 3D printing technology in implant dentistry. The results highlight the potential of 3DISFP with OnX resin to improve oral health-related quality of life in edentulous patients. Continued advancements in 3D printing materials and techniques will likely expand the utilization of these prostheses, ultimately benefiting patients in need of implant-supported restorations.

Effect of hemispherical dimples at titanium implant abutments for the retention of cemented crowns.

PURPOSE: The aim of this study was to assess the effect of hemispherical dimple structures on the retention of cobalt-chromium (Co-Cr) crowns cemented to titanium abutments, with different heights and numbers of dimples on the axial walls. MATERIALS AND METHODS: 3.0-mm and 6.0-mm abutments (N = 180) and Co-Cr crowns were prepared. The experimental groups were divided into two and four dimple groups. The crowns were cemented by TempBond and PANAVIA F 2.0 cements. The retention forces were measured after thermal treatments. A two-way Analysis of Variance (ANOVA) and post-hoc Tukey HSD test were conducted to analyze change in retention forces by use of dimples between groups, as well as t test for the effect of abutment height change (α = .05). RESULTS: Results of the two-way ANOVA showed a statistically significant difference in retention force due to the use of dimples, regardless of the types of cements used (P < .001). A significantly higher mean retention forces were observed in the groups with dimples than in the control group, using the post hoc Tukey HSD test (P < .001). Results of t test displayed a statistically significant increase in the retention force with 6.0-mm abutments compared with 3.0-mm abutments (P < .001). The groups without dimples revealed adhesive failure of cements, while the groups with dimples showed mixed failure of cements. CONCLUSION: Use of hemispherical dimples was effective for increasing retention forces of cemented crowns.

Rehabilitation of distal extension maxillary ridges with fixed and removable implant-supported prostheses: Preliminary 12-month randomized clinical trial.

PURPOSE: This trial evaluated clinical outcomes of fixed and removable implant-supported prostheses for rehabilitation of atrophied distal extension maxillary ridges. MATERIALS AND METHODS: A total of 54 participants with atrophied distal extension maxillary ridges were randomly assigned into three groups (n = 18/group). Group I (SLF); participants treated with fixed restoration supported by three long implants after sinus augmentation, Group II (SF); participants treated with fixed restoration supported by one long and two short implants, and Group III (OD): participants treated with removable partial denture assisted by one long implant that was placed mesial to maxillary sinus (IARPD). Modified plaque index (MPI), modified gingival index (MGI), pocket depth (PD), implant stability (IS), and crestal bone loss (CBL) were measured after prosthesis insertion (T0), 6 (T6), and 12 months (T12) after insertion. Patient satisfaction was measured at T12 using a visual analog scale (VAS). RESULTS: The implant survival rates were 96.8%, 92.4%, and 84.6% for SLF, SF, and OD groups respectively. The SLF recorded the highest MPI, MGI, PD, and IS values, followed by the SF, and the OD showed the lowest values. The OD recorded the highest CBL followed by the SF and the SLF showed the lowest CBL. With exception of satisfaction with surgery and cleaning, SLF and SF groups recorded significantly higher patient satisfaction than the OD for all VAS questions. CONCLUSION: Fixed restorations supported with either long or short implants were associated with improved implant stability, reduced bone loss, and increased patient satisfaction compared to implant-assisted RPDs. However, implant-assisted RPDs were associated with more favorable peri-implant soft tissue health and increased satisfaction with surgery, healing, and cleaning.

Contour angle and peri-implant tissue height: Two interrelated features of the implant supracrestal complex.

OBJECTIVES: Recent research has suggested the contour of the prosthesis and the vertical height of the peri-implant mucosa as important parameters that can influence the long term health and stability of the peri-implant tissue. In particular, overcontouring of the prosthesis has been correlated with an increased risk for peri-implantitis, while reduced soft tissue height has been associated with marginal bone loss, recession, and other soft tissue complications. Although these two parameters have been investigated as independent in the current literature, clinical experience points toward a close interrelation between transmucosal tissue height and prosthesis contour angle. It is often found that a reduced vertical height of the implant supracrestal complex is the main reason for overcontouring of the prosthesis. At the same time, achieving a favorable contour of 30o or less is not possible unless the clinician has ensured an adequate vertical height of the soft tissue. The purpose of this short communication is to establish the relation between tissue vertical height and prosthesis contour by utilizing a theoretical geometry equation based on the Pythagorean theorem. In doing so, one can use the dimensions of the implant as well as those of the prosthesis at the mucosal margin to calculate the essential vertical height for achieving a favorable prosthesis contour. CONCLUSIONS: As the treatment plan of the implant supracrestal complex is "top-down," in case of deficient vertical height, subcrestal placement of the implant should be considered to achieve a proper prosthesis contour.

The distribution of marginal excess cement of implant-supported vented and non-vented zirconia crowns with and without cleaning procedures.

PURPOSE: To investigate the distribution of marginal excess cement in vented and non-vented crowns and evaluate the effect of clinical cleaning procedures on the reduction of excess cement. MATERIALS AND METHODS: Forty models with implant analogs in the position of the right maxillary first molar were divided into four groups (n = 10/group, vented/non-vented crowns with or without cleaning procedures). The abutment finish lines were placed 1 mm below the artificial gingiva buccally, mesially, and distally and at the gingival level palatally. A standardized amount (20 mg) of resin cement was applied in a thin layer to the intaglio surface of zirconia vented and non-vented crowns. The excess cement was removed by a dental explorer in groups with cleaning procedures. The distribution (area and depth) of the marginal excess cement was measured at each quadrant (buccal, mesial, palatal, and distal) for all study samples. The data were analyzed using descriptive and analytical statistics (ɑ = 0.05). RESULTS: The area and depth values of the excess cement in each quadrant in the vented group were significantly smaller than that in the non-vented group, both with and without cleaning (p < 0.001). Cleaning procedures significantly reduced the area of excess cement in both vented and non-vented groups (all, p < 0.001 except for p < 0.05 at the buccal aspect of the vented group). The depth of excess cement in the vented group was significantly decreased with cleaning in the buccal quadrant compared with that without cleaning (p < 0.01). However, the depth of excess cement of the non-vented group was significantly increased with cleaning in all quadrants compared with that without cleaning (all, p < 0.001 except for p < 0.05 at the distal aspect). CONCLUSIONS: Crown venting significantly reduced the area and depth of the marginal excess cement in vitro. Cleaning procedure with a dental explorer significantly reduced the area of marginal excess cement in vitro; however, the excess cement can be pushed deeper in the non-vented group.

Implant prosthodontic design as a predisposing or precipitating factor for peri-implant disease: A review.

Over the past decade, emerging evidence indicates a strong relationship between prosthetic design and peri-implant tissue health. The objective of this narrative review was to evaluate the evidence for the corresponding implant prosthodontic design factors on the risk to peri-implant tissue health. One of the most important factors to achieve an acceptable implant restorative design is the ideal implant position. Malpositioned implants often result in a restorative emergence profile at the implant-abutment junction that can restrict the access for patients to perform adequate oral hygiene. Inadequate cleansability and poor oral hygiene has been reported as a precipitating factors to induce the peri-implant mucositis and peri-implantitis and are influenced by restorative contours. The implant-abutment connection, restorative material selection and restoration design are also reported in the literature as having the potential to influence peri-implant sort tissue health.

Prevention of peri-implant disease in edentulous patients with fixed implant rehabilitations.

OBJECTIVES: To provide an overview about the current approaches to prevent peri-implant diseases in edentulous patients with complete-arch implant-supported prostheses, and to review the clinical applications of the latest digital technologies for implant prosthodontics. METHODS: A review of the guidelines to prevent peri-implant diseases in patient's receiving complete-arch implant-supported prostheses including facially driven treatment planning procedures using either conventional or digital methods, computer-aided implant planning procedures, and prosthodontic design variables including the optimal number and distribution of dental implants, implant to abutment connection type, implant or abutment level design, screw- or cement-retained alternatives, prostheses contours, and material selection is provided. Furthermore, an outline of the current therapeutic management approaches to address peri-implant diseases is reviewed. CONCLUSIONS: Clinicians should understand and know different planning and design-related variables that can affect biological and mechanical complication rates of complete-arch implant-supported prostheses. Maintenance protocols are fundamental for minimizing biological and mechanical complications.

Comparative evaluation of short or standard implants with different prosthetic designs in the posterior mandibular region: a three-dimensional finite element analysis study.

The purpose of this study is to evaluate the stress distribution of splinted or nonsplinted restorations supported by 2 short or 2 standard dental implants in the mandibular molar region using three-dimensional finite element analysis. Two standard implants (4.8 × 10mm) were placed in the mandibular molar area. Two short implants (4.8 × 6 mm) were located in the mandibular molar atrophied area. Implant-supported prostheses were simulated with splinted or nonsplinted crowns design. Vertical load of 200 N and oblique load of 100 N were applied on the central fossa and the buccal cusps. Evaluation of stress distribution in implants and peri-implant cortical bone using the finite element analysis software (Ansys, Version 2020, R2), a multipurpose computer design program. The maximum principal stress of cortical bone around the implants was higher in nonsplinted crowns when compared to splinted crowns. The stress concentration of cortical bone surrounding implants increased as the implant length decreased either splinted crowns or nonsplinted crowns. The short implants with nonsplinted crowns showed lower stresses when compared to standard implants with nonsplinted crowns. The results suggest that the nonsplinted prostheses supported by short dental implants might be considered in the molar area of the atrophic mandible.

Effect of Vent Hole and Cement Type on Fracture Resistance of CAD-CAM Monolithic Zirconia Crowns.

PURPOSE: To assess the fracture resistance of monolithic zirconia crowns cemented with different types of cement on cement-retained implant abutments. MATERIALS AND METHODS: Forty implant analogs were positioned in acrylic resin blocks, and cement-retained straight implant abutments were fastened to the analogs. Crowns were designed with/without occlusal vent holes and produced from monolithic zirconia blocks by the CAD-CAM technique. The two crown types were divided into two groups and cemented with resin and zinc-polycarboxylate cement under 5 kg weight. A universal testing machine applied compressive forces to the crowns until fracture. Fracture resistance values were analyzed using two-way ANOVA and the independent samples t-test with statistical significance set at p < 0.05. RESULTS: According to the two-way ANOVA results, although the crown design did not have a significant effect on fracture resistance (1417.65 ± 337.39 N, 1565.16 ± 517.12 N; crowns with and without vent holes, respectively), the main effect of the cement variable on the fracture resistance was significant. Zinc-polycarboxylate cement (1680.1 ± 375.23 N) showed higher fracture resistance than resin cement (1302.71 ± 420.64 N) in the crowns designed with vent holes (p < 0.005). CONCLUSION: The use of cement-retained implant-supported monolithic zirconia crowns with an occlusal vent hole is safe, and zinc-polycarboxylate cement use may be an appropriate choice for cementation of these crowns.

Impact of local predisposing/precipitating factors and systemic drivers on peri-implant diseases.

BACKGROUND: Strong evidence suggests the infectious nature of peri-implant diseases occurring in susceptible hosts. Epidemiological reports, though, indicate that peri-implantitis is a site-specific entity. Hence, the significance of local factors that may predispose/precipitate plaque accumulation and the impact of systemic drivers that alter the immune response are relevant in the prevention and management of peri-implant disorders. PURPOSE: The purpose of the present review is to shed light on the significance of local and systemic factors on peri-implant diseases, making special emphasis on the associations with peri-implantitis. METHODS: The biologic plausibility and supporting evidence aiming at providing a concluding remark were explored in the recent scientific literature for local predisposing/precipitating factors and systemic drivers related to peri-implant diseases. RESULTS: Local predisposing factors such as soft tissue characteristics, implant position and prosthetic design proved being strongly associated with the occurrence of peri-implant diseases. Hard tissue characteristics, however, failed to demonstrate having a direct association with peri-implant diseases. Robust data points toward the strong link between residual sub-mucosal cement and peri-implant diseases, while limited data suggests the impact of residual sub-mucosal floss and peri-implantitis. Systemic drivers/habits such as hyperglycemia and smoking showed a strong negative impact on peri-implantitis. However, there is insufficient evidence to claim for any link between metabolic syndrome, atherosclerotic cardiovascular disease, and obesity and peri-implant diseases. CONCLUSION: Local predisposing/precipitating factors and systemic drivers may increase the risk of peri-implant diseases. Therefore, comprehensive anamnesis of the patients, educational/motivational programs and exhaustive prosthetically-driven treatment planning must be fostered aiming at reducing the rate of biological complications in implant dentistry.

Pink gingival restoration: An acceptable treatment for complex ridge defects.

Complex implant prosthetic reconstruction poses several challenges. The lost anatomy of periodontium due to trauma or long-standing missing teeth, especially in esthetic area, requires several surgical visits for recovery. The augmentation procedures are technique sensitive and unpredictable and need long commitment from the patient. They are time-consuming and expensive, and patients are often unwilling. The alternative for anatomically deficient partial edentulous sites could be prosthetic gingival restoration. They help in re-establishing natural contours, interproximal papilla, and further eliminating complex procedures. The other advantage is perfect horizontal and vertical transition between the prosthesis and adjacent tissues. This article describes two cases of completed gingival prosthetic prosthesis which corrected the missing architectures around lost teeth. It was well accepted by the patients and can be an alternative for unpredictable regenerative procedures.

[Experimental design of the lower jaw functional loading for implant-supported restoration in unfavorable clinical conditions]. / Eksperimental'noe modelirovanie funktsional'noi nagruzki nizhnei chelyusti pri protezirovanii s oporoi na implantaty v neblagopriyatnykh klinicheskikh usloviyakh.

THE AIM OF THE STUDY: Was to create a finite element design to evaluate the masticatory stress distribution on the full fixed prosthesis with three supporting implants and the mandibular bone in the conditions most closely resembling the real ones. MATERIALS AND METHODS: The geometric design was created with the results of a CBCT of a real patient. The transfer of the DICOM into STL format was carried out in the Mimics Medical 21 program, in which the author's splinting device for the implant was designed. The actual thicknesses of the patient's compact and cancellous bone layers were measured with Romexis ver. 4.5.1. Scanning of the artificial dentition was performed with the iTero Element 2 Version 1.7 which created an object in STL format. Design was performed in the package for finite element analysis Ansys 19.3. Tetrahedral elements of the second order were used for calculation. The structural elements were connected in the model by a rigid «Bonded¼ contact. RESULTS: A finite element model has been created for the experimental load design on the lower jaw for immediate implant restoration with few supports in combination with a device for stabilizing the implant in unfavorable clinical conditions. It is shown that the designed finite element model takes into account the biomechanics of the prosthesis with few supports. When calculating, the entire model was fixed to the mandibular process at its base, and was loaded with a force of 500 N, distributed over the teeth. The values of the maximum stresses obtained in the elements were 51.8 MPa for the compact layer and 245 MPa for titanium elements. CONCLUSION: Thus, we created personalized geometric and finite element models for calculating the distribution of functional load on a long full fixed implant-supported prosthesis with few artificial supports, which makes the experimental results more accurate and correct.

Immediate flapless full-arch rehabilitation of edentulous jaws on 4 or 6 implants according to the prosthetic-driven planning and guided implant surgery: A retrospective study on clinical and radiographic outcomes up to 10 years of follow-up.

OBJECTIVES: to retrospectively evaluate clinical and radiographic outcomes of immediate, flapless full-arch prostheses, supported by 4/6 implants according to prosthetic-driven planning and guided surgery. MATERIALS AND METHODS: The study involved 28 edentulous patients (20 female/8 males; average age 67.75 ± 8.627 years), 32 prostheses (17 all-on-4/15 all-on-6) and 164 implants. The Implants survival, prostheses success/survival, peri-implant marginal bone loss, incidence of biological and prosthetic complications were evaluated. Multiple linear regression analysis was performed to analyze the influence of implant and patient characteristics on marginal bone loss. RESULTS: Cumulative implant survival rate was 89.7% for all-on-four (seven failures) and 99.0% for all-on-six (one failure) after a mean follow-up of 6.46 ± 2.236 years (range 1-10 years). Cumulative prosthesis success rate was 51.5% (58.8% for all-on-four/ 43.8% for all-on-six). Prosthesis survival rate was 88.2% for all-on-four. No failure was registered in all-on-six. Mean value of marginal bone loss was 1.38 ± 0.1.28 mm at 5-year and 2.09 ± 0.56 mm at 10-year follow-up. No difference was found in the mean value of marginal bone resorption between all-on-four (1.56 ± 1.61 mm) and all-on-six (1.20 ± 0.85 mm) (p = 0.104) and between tilted (1.22 ± 1.29 mm) and axial implants (1.44 ± 1.27 mm) (p = 0.385) after 5-year follow-up. The incidence of biological complications was 1.0% in all-on-six (one mucositis) and 10.3% in all-on-four (two peri-implantitis). Prosthetic complications affected teeth of final rehabilitations with 3 detachments, 10 chippings or fractures, and 3 severe occlusal wears. CONCLUSIONS: Based on the results and within the limitations of the present study, the implant-supported hybrid prosthesis according to prosthetic-driven planning and guided surgery showed to be an efficient, safe, and effective approach to rehabilitate edentulous jaws.