Biomechanical behavior of all-on-4 concept and alternative designs under different occlusal load configurations for completely edentulous mandible: a 3-D finite element analysis.

The aim of this study was to evaluate the effect of the All-on-4 design and 4 alternative implant-supported fixed prosthesis designs on stress distribution in implants, peri-implant bone, and prosthetic framework in the edentulous mandible under different loading conditions using three-dimensional finite element analysis (3D-FEA).Five different experimental finite element models (Model A (unsplinted 6), Model B (splinted 6), Model C (All-on-4), Model D (axial; 2 anterior, 2 posterior), and Model E (4 interforaminal)) were created. Three different loading conditions were applied (canine loading, unilateral I-loading, and unilateral II-loading). The highest minimum (Pmin) and the maximum (Pmax) principal stress values were acquired for cortical and trabecular bones; the highest von Mises (mvM) stress values were obtained for implants and metal frameworks. Model B and Model D showed the most favorable stress distribution. The All-on-4 design (Model C) also showed acceptable stress values close to those of Model B and Model D in the cortical and trabecular bones. In accordance with the stress values in the bone structure, the lowest stress values were measured in the implants and Co-Cr framework in Model B and Model D. The highest stress values in all structures were measured for unilateral loading- II, while the lowest values were found for canine loading. It was concluded that Model B and Model D experimental models showed better biomechanical performance in all structures. Furthermore, the use of a splinted framework, avoiding cantilevers, results in lower stress transmission. On the other hand, canine loading and unilateral loading-I exhibited the best loading conditions.

Comparative biomechanics of all-on-4 and vertical implant placement in asymmetrical mandibular: a finite element study.

BACKGROUND: Clinical scenarios frequently present challenges when patients exhibit asymmetrical mandibular atrophy. The dilemma arises: should we adhere to the conventional All-on-4 technique, or should we contemplate placing vertically oriented implants on the side with sufficient bone mass? This study aims to employ three-dimensional finite element analysis to simulate and explore the biomechanical advantages of each approach. METHODS: A finite element model, derived from computed tomography (CT) data, was utilized to simulate the nonhomogeneous features of the mandible. Three configurations-All-on-4, All-on-5-v and All-on-5-o were studied. Vertical and oblique forces of 200 N were applied unilaterally, and vertical force of 100 N was applied anteriorly to simulate different masticatory mechanisms. The maximum von Mises stresses on the implant and framework were recorded, as well as the maximum equivalent strain in the peri-implant bone. RESULTS: The maximum stress values for all designs were located at the neck of the distal implant, and the maximum strains in the bone tissue were located around the distal implant. The All-on-5-o and All-on-5-v models exhibited reduced stresses and strains compared to All-on-4, highlighting the potential benefits of the additional implant. There were no considerable differences in stresses and strains between the All-on-5-o and All-on-5-v groups. CONCLUSIONS: With the presence of adequate bone volume on one side and severe atrophy of the contralateral bone, while the "All-on-4 concept" is a viable approach, vertical implant placement optimizes the transfer of forces between components and tissues.

Effect of different intraoral scanners and scanbody splinting on accuracy of scanning implant-supported full arch fixed prosthesis.

OBJECTIVE: This study evaluated the accuracy of different intraoral scanners (IOS) for scanning of implant-supported full arch fixed prosthesis with different implant angulations with and without scanbodies splinting. MATERIALS AND METHODS: Two maxillary models were designed and fabricated to receive an all-on-four implant retained. The models were divided into two groups according to the angulation of the posterior implant (Group 1; 30 and Group 2; 45). Each group was then divided into three subgroups according to the type of IOS used: Subgroup C; Primescan, subgroup T; Trios4, and subgroup M; Medit i600. Then each subgroup was divided into two divisions according to scanning technique; division S: splinted and division N: nonsplinted. Ten scans were made by each scanner for every division. Trueness and precision were analyzed using Geomagic controlX analysis software. RESULTS: Angulation had no significant effect on both the trueness (p = 0.854) and precision (p = 0.347). Splinting had a significant effect on trueness and precision (p < 0.001). Scanner type had a significant effect on trueness (p < 0.001) and precision (p < 0.001). There was no significant difference between trueness of Trios 4 (112.15 ± 12.85) and Primescan (106.75 ± 22.58). However, there was a significant difference when compared to trueness of Medit i600 (158.50 ± 27.65). For the precision results Cerec Primescan showed the highest precision (95.45 ± 33.21). There was a significant difference between the three scanners, precision of Trios4 (109.72 ± 19.24) and Medit i600 (121.21 ± 17.26). CONCLUSION: Cerec Primescan has higher trueness and precision than Trios 4 and Medit i600 in full arch implants scanning. Splinting the scanbodies improve the accuracy of full arch implants scanning. CLINICAL SIGNIFICANCE: Cerec Primescan and 3Shape Trios 4 can be used for scanning of All-on-four implant supported prosthesis when scanbodies are splinted using a modular chain device.

Fiber-Reinforced Hybrid Prosthesis Veneered With Composite Resin for 4 Implant-Supported Fixed Provisional and Definitive Restorations.

This technical note describes the fabrication and benefits of fiberglass-reinforced hybrid prosthesis veneered with composite resin for 4 implant-supported fixed professional and final restorations. The described prosthesis reduces rehabilitation time, minimizes impression problems, and ensures a passive fit of professional restoration. The prosthesis provides immediate rehabilitation of 4 implants with ease of adjustments and repair during the entire provisional phase. Moreover, it can be easily converted to final restoration with minimal modifications, excellent esthetic results, and reduced costs.

Integration of conventional and digital surgical guide fabrication techniques for the partially edentulous patient: Reducing the number of surgical procedures for a complete arch implant-supported prosthesis.

Surgical procedures on partially edentulous patients for complete arch implant-supported prostheses involve remaining tooth extraction, alveolar bone reduction, and implant placement. Traditionally, partially edentulous patients undergo multiple surgeries, which extends the healing time and results in an extensively prolonged total treatment timeline. This technical article focuses on the fabrication of a more stable and predictive surgical guide to perform multiple surgical procedures in a single surgical appointment and planning a complete arch implant-supported prosthesis for the partially edentulous patient.

Functional and aesthetic rehabilitation using 'all on 4' treatment protocol with intraoral welding.

With the increasing life expectancy and improved quality of life, the conventional prosthodontic removable treatment modalities are being replaced with implant retained fixed prostheses. A full-arch conventional rehabilitation of edentulous ridges requires six to ten dental implants. However, some patients demand fixed implant-supported prostheses inspite of medical conditions and economic concerns. Also in completely edentulous cases, the insufficient bone morphology directs the treatment plan towards alternatives such as cantilever prostheses, short implants or ridge augmentation procedures. These clinical conditions have brought in a quantum shift in treatment planning towards the 'all on 4 protocol' providing immediately loaded fixed prosthesis supported by 4 implants thereby providing optimum and immediate restoration of function and esthetics.

Accuracy of different laboratory scanners for scanning of implant-supported full arch fixed prosthesis.

OBJECTIVE: This study evaluated the accuracy of different laboratory scanners (LS) for scanning of implant-supported full arch fixed prosthesis with different implant angulations. MATERIALS AND METHODS: Two maxillary models that are designed to receive an all-on-four implant retained prosthesis were fabricated then scanned using five different LS. The models were divided into two groups according to the angulation of the posterior implant (Group 1; 30° and group 2; 45°). Each group was then subdivided into five subgroups according to the type of LS, subgroup T; Medit T710, subgroup I; IneosX5, subgroup E; 3ShapeE4, subgroup A; Autoscan DS-Mix, and subgroup M; Ceramill Map600. An industrial 3D scanner was used as reference scanner, then each model was scanned with 5 LS 10 times. Trueness and precision were analyzed using Geomagic 3D analysis software. RESULTS: Both scanner type and implant angle had a significant effect on the trueness (p < 0.001). Significant interaction was found between the scanner type and implant angle (p < 0.001). For scanner type tukeys post hoc test revealed highest trueness with the 3Shape E4 (21.3 ± 2.1) and the medit T710 (22.6 ± 2.1) and least trueness with the shining 3D autoscan ds-mix (33.8 ± 3.0). Significantly better trueness was observed with the 30° than the 45° angle. Regarding precision, two-way ANOVA revealed significant effect of the scanner type only (p < 0.001). There were no significant differences between the 3Shape E4, medit T710, Ineos X5, and the Ceramill map600. However, all showed significantly higher precision values when compared to shining 3D autoscan ds-mix. CONCLUSIONS: All tested scanners showed results within the clinically acceptable range with 3ShapeE4 and Medit T710 showing the highest accuracy. CLINICAL SIGNIFICANCE: Tested scanners can be used for scanning of All-on-four implant supported prosthesis.

Biomechanical analysis of stress around the tilted implants with different cantilever lengths in all-on-4 concept.

BACKGROUND: Many clinical studies have reported the high success rate of the All-on-4 concept. In the present study, we aimed to compare the stress distribution with different tilted distal implants and cantilever lengths in an All-on-4 system using the two-dimensional photoelastic method and to establish the All-on-4 implant photoelastic model by computer-aided design (CAD) and rapid prototyping (RP).  METHODS: The data of the human edentulous mandible were acquired by computed tomography (CT). Three human edentulous mandible All-on-4 implant models with different distally inclined implant holes were fabricated using Mimic, Geomagic Studio software, and a light solidifying fast shaping machine. Then the final photoelastic models were established through the traditional method. Each of the three models had four NobelSpeedy Replace implants between the interforaminal regions. The two posterior implants were placed 0, 15, and 45 degrees distally before the mental foramen. The four implants were splinted by wrought cobalt-chromium alloy frameworks. Each of the three photoelastic models was submitted to a 150 N vertical load at five points on the framework: the central fossa of the mandibular first molar, and 0 mm, 5 mm, 10 mm, and 15 mm of the cantilever length. The stress produced in the models was photographed with a digital camera, and the highest value of the stressed fringe pattern was recorded. RESULTS: The All-on-4 implant photoelastic model established by CAD and RP was highly controllable and easy to modify. The position and inclination of implants were accurate, and the frameworks could be passively emplaced. The stress values were higher around a single tilted implant compared with the distal implant in All-on-4 with the same inclination. The 0-degree distal implant and 45-degree distal implant demonstrated the highest and lowest stress when loading at the central fossa of the mandibular first molar, respectively. With the same inclination of distal implant, the peri-implant bone stress increased as the length of cantilever increased. CONCLUSION: The method of establishing the All-on-4 implant photoelastic model by CAD and RP was highly controllable, convenient, fast, and accurate. The tilted implants splinted in the fully fixed prosthesis with reduced cantilever lengths did not increase the stress level compared with the vertical distal implants.And this illustrated that the influence of cantilever on stress distribution was greater than the influence of implant inlination.

Stresses induced by one piece and two piece dental implants in All-on-4® implant supported prosthesis under simulated lateral occlusal loading: non linear finite element analysis study.

BACKGROUND: Correct choice of the implant design and the occlusal scheme is important for the success of implant supported restorations. So, the aim of the current study was to find out the difference in the stresses induced by the one piece dental implants designed to be used in the All-on-4® concept and the conventional two piece ones under simulated lateral occlusal schemes using nonlinear finite element analysis. METHODS: Two finite element models of the maxilla, implants, and prostheses were designed according to the All-on-4® concept. In the model TP, two piece dental implants were placed while in the model OP one piece dental implants were used. Two loading scenarios were applied to each model; the first one simulated a group function occlusal scheme while the second scenario simulated a canine guided one. RESULTS: The highest stress value was recorded in the model TP with the group function occlusion and the lowest stress value was in the model OP with the canine guidance occlusion. CONCLUSION: The one-piece dental implants can be concluded to induce less stress compared to the two piece dental implants when used in the All-on-4® implant supported prosthesis in the different lateral occlusal schemes. Canine guided occlusion can be concluded to cause lower stress values in comparison to the group function occlusal scheme.

ZYGOMATIC IMPLANTS MAY IMPROVE QUALITY OF LIFE AND SATISFACTION IN PATIENTS WITH ATROPHIED MAXILLA.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Alberto J, Mariano S, Guerrero-s Y, Pato-mourelo J. Evaluation of Quality of Life And Satisfaction in Patients with Fixed Prostheses on Zygomatic Implants Compared with the All-on-Four Concept: A Prospective Randomized Clinical Study. Int J Environ Res Public Heal. 2021; 18(3426). SOURCE OF FUNDING: The Department of Oral Surgery, University of Murcia, Murcia, Spain. TYPE OF STUDY/DESIGN: Prospective randomized clinical trial.

Traditional prosthetic workflow for implant rehabilitations with a reduced number of fixtures: proposal of a protocol.

The aim of this study was to describe a standardized protocol for the creation of a definitive prosthetic rehabilitation supported by a reduced number of implants, achievable with a limited number of an optimized appointments. The proposed protocol provides only for 4 appointments to finalize the set work. During the first appointment, definitive impressions are taken in order to obtain the master models and plaster bars. The second appointment is the most important: the aesthetic and functional evaluations of the provisional prostheses are carried out and the plaster bars tested. During the third appointment the teeth test is performed, with the corresponding phonetic and functional test. In the fourth appointment the definitive prostheses are delivered and screwed. The fundamental aspect of prosthetic finalization is the simplification and standardization of protocols to obtain better control of all different steps and to reduce the number of appointments with the patient. The realization of a correct definitive prosthesis is the key to long-term success in implant rehabilitation and can improve the patient's quality of life in various aspects. By optimising the time and standardising the procedures, it is possible to make definitive prostheses for rehabilitations with a reduced number of implants of excellent quality in only 4 appointments.

Minimally invasive digital implant-prosthetic procedure in "all on 4" rehabilitation in patients with special needs: a three-year follow-up.

The present study describes an innovative procedure for resolving implant-prosthetic cases in patients with edentulous special needs. In 2017 a 56-year-old female patient came to the Department of Dentistry of Vita-Salute San Raffaele Hospital, Milan, Italy, requiring implant-prosthetic rehabilitation of the dental arches given the difficulty in wearing removable prostheses. The first level radiological examinations were evaluated, two technical photographs were taken with specific reference, the 2D Digital Smile Design (Smile Design) was then carried out, the provisional prosthesis was performed and the CBCT requested with repere and provisional prostheses to realize the computerized implant project and an atraumatic flapless guided surgery. Professional oral hygiene sessions were performed quarterly, and the 3-year follow-up revealed no complications affecting the prosthetic or implant component. We can therefore conclude that the proposed method, exploiting digital technologies and flows and minimally invasive flapless surgical methods, can be considered elective in the treatment of patients with special needs.

A simplified digital workflow for the prosthetic finishing of implant rehabilitations: a case report.

The aim of this article is to describe how, during the provisional and definitive prosthetic phases, using new digital technologies, it is possible to improve the ergonomics of the prosthetist's work and reduce the discomfort of patients, subjecting them to the fewest possible appointments at the dentist. The proposal of a full digital protocol, described by the following case report, for the realization of a definitive prosthetic rehabilitation supported by a reduced number of implants, in fact, allows to considerably reduce the number of appointments and reduce any bias. A 67-year-old male patient presents for the first visit to the Department of Dentistry of the San Raffaele Hospital, wearing a removable upper prosthesis and with the request to heal the aesthetic and functional situation through prosthetics fixed. An initial panoramic radiograph was performed, intra and extra oral photos were taken and also intraoral impressions. A stereo-lithographic models are obtained from intraoral scans, and two total prostheses, upper and lower, were packaged for the provisional post-surgical phase was performed. In accordance with the All-on-4 method 8 implant fixtures were placed. For the final prosthetic phase, the patient underwent only two operative sessions. In the first session, scans were taken with the provisionals in situ, of the patient's mucous membranes and with the Scan-abutments in place. In the second session using specific CADSoftware the matching of the STL files of the three scans were created, the opposing arches of the patient were related on a digital articulator, and the milled titanium bars were immediately constructed and finished with the resin. Finally, the definitive prostheses were delivered to the patient without any other test. Digital technology has allowed a clear reduction in working times and costs and has allowed the reduction of stress for patients who undergo invasive and extensive treatments to recover aesthetics and function, and for clinicians who must manage complex cases with fewer appointments possible.

Atrophic Maxilla Rehabilitation Through Dental Implants Using the V-4 Strategy Associated With Guided Surgery: A Case Report and Technique Description.

Atrophic maxilla rehabilitation through dental implants is always a challenging procedure. However, alternative approaches such as guided surgery and the installation of short implants are progressively supplanting more invasive bone regeneration procedures. A V-4 technique described in 2016 facilitates the installation of dental implants in patients with atrophic maxilla; however, its authors recommend incision, flap opening, and elevation of the anterior area of the maxillary sinuses. This case report describes a less invasive proposal for modifying the technique through the association of guided surgery, which improves implant placement accuracy, shortens surgical time, and reduces morbidity.

Rehabilitation of Severe Atrophic Ridges with Zygomatic Implant and/or All-on-4 Treatment Concepts-A Case Series.

Rehabilitation of completely edentulous patients with implant-supported prosthesis (ISP) is the need of the day, but in many patients, the routine ISP is not possible due to the severe atrophic residual ridges. The present case series describes three cases with atrophic ridges rehabilitated using zygomatic implants and/or All-on-4 treatment concepts. In case 1 and case 3, in maxillary arch, there was not enough bone in Zone 3 to rehabilitate the patient with routine protocol followed for the All-on-4 treatment concept, so in these two cases, zygomatic implants were placed. Case 1 and case 2 were rehabilitated with Malo Bridge and case 3 with acrylic teeth-hybrid prosthesis using a computerized milling procedure to obtain improved fit, function, esthetics, and ease of retrievability whenever required.

Postoperative discomfort after implant placement according to the All-on-4 concept with or without Zygoma implants: A prospective clinical study.

OBJECTIVES: The purpose of the study was to assess patients' postoperative discomfort after implantations according to the All-on-4 concept with and without using Zygoma implants. MATERIAL AND METHODS: Three treatment groups were formed for this prospective study: All-on-4 rehabilitation in the maxilla (group 1, N = 25), All-on-4 rehabilitation in the maxilla using at least two Zygoma implants (group 2, N = 25), and All-on-4 rehabilitation in the mandible (group 3, N = 20). Principal outcome parameters were postoperative pain (100 mm VAS) and perceived swelling (100 mm VAS). Also, the use of analgesics was documented. RESULTS: The worst postoperative pain of 21.3 (SD 18.9) VAS was observed in group 2, but there was no statistically significant difference between the groups (mixed ANOVA p = .791). The postoperative total intake of painkillers was significantly higher in group 2 than in the other groups (p < .001). On postoperative day 28, the mean pain scores in all groups declined to values below 5 VAS. Postoperative perceived swelling in group 2 was significantly more severe than it was in group 1 and 3 (p < .001). CONCLUSIONS: The use of Zygoma implants in All-on-4 surgical interventions had an essential effect on postoperative swelling, but less so on postoperative pain. The slightly increased, but statistically not significantly different postoperative pain in group 2 was compensated by an overall higher postoperative intake of painkillers compared to the other groups.

Stress Distribution on the Prosthetic Screws in the All-on-4 Concept: A Three-Dimensional Finite Element Analysis.

The all-on-4 concept, which is used to rehabilitate edentulous patients, can present with mechanical complications such as screw loosening and fracture. The purpose of this study was to evaluate the stress patterns induced in the prosthetic screws by the different prosthetic screw and abutment designs in the all-on-4 concept using finite element analysis. Von Mises stress values on 6 groups of each screw type, including short and narrow screw, short abutment; short and wide screw, short abutment; long and wide screw, short abutment; short and narrow screw, long abutment; short and wide screw, long abutment; and long and wide screw, long abutment, were compared under a cantilever loading of 200 N that was applied on the farther posterior to the position of the connection between the distal implant and the metal framework. Posterior prosthetic screws showed higher stress values than anterior prosthetic screws. The stress values in posterior prosthetic screws decreased as the length and diameter increased. In conclusion, the long and wide screw design offers advantages in stress distribution when compared with the short and narrow design.

Patient satisfaction and oral health-related quality of life (OHRQoL) of conventional denture, fixed prosthesis and milled bar overdenture for All-on-4 implant rehabilitation. A crossover study.

OBJECTIVES: This study aimed to evaluate patient satisfaction and oral health-related quality of life (OHRQoL) of conventional denture, fixed prosthesis and milled bar overdenture for All-on-4 implant rehabilitation. MATERIALS AND METHODS: Sixteen completely edentulous patients with ill-fitted mandibular dentures received new mandibular dentures (CDs). After 3 months, 4 implants were installed according to the "All-on-4 concept" and immediately loaded with mandibular dentures. Three months after osseointegration, patients received either fixed prosthesis (FP) or milled bar overdenture (MB) in a crossover design. Patient satisfaction was evaluated using a visual analog scale (VAS). OHRQoL was evaluated using the OHIP-14. Questionnaires of VAS and OHIP-14 were measured 3 months after wearing each of the following prostheses: CD, FP, and MB. RESULTS: For all questions of VAS and OHIP-14, CD showed significant lower satisfaction compared to FP and MB (p < .00025). FP recorded significant higher VAS scores than MB regarding retention and stability (p < .00007). MB recorded significant higher scores than FP regarding general satisfaction, comfort, ease of cleaning, and handling (p < .00008). Regarding OHIP-14, no significant differences in OHIP scores between FP and MB were observed for all domains of OHIP. CONCLUSION: "All-on-4" implant rehabilitation of edentulous mandible with FP and MB achieves high patient satisfaction and OHRQoL compared to CD. No significant difference in OHRQoL between FP and MB was observed. Regarding VAS, FP rated greater satisfaction with retention, stability, and chewing compared to MB. However, MB rated greater satisfaction with ease of cleaning and handling compared to FP.

A prospective study of changes in oral health-related quality of life during immediate function implant procedures for edentulous individuals.

OBJECTIVE: The aim of this prospective clinical study was to evaluate longitudinal changes in oral health-related quality of life (OHRQoL) attributable to fixed dental prostheses during All-on-4(®) treatment in one or both jaws. MATERIALS AND METHODS: Ten patients underwent placement of four or six endosteal dental implants on the basis of the All-on-4(®) treatment concept in the edentulous maxilla or both jaws and immediate loading with acrylic interim prostheses. The prostheses were replaced after 3-6 months, and definitive prostheses with titanium framework and reinforced resin facing were fixed after another 5 months or more. The subjects completed the shortened Japanese version of the Oral Health Impact Profile (OHIP-J14) before the surgery (T0), 1 week after the initial (T1) and secondary (T2) interim prostheses were placed, and 3 months after definitive prosthesis placement (T3). Complete data of nine subjects were analyzed with the Wilcoxon signed-rank test. RESULTS: The total OHIP-J14 score significantly reduced only at T3 (P < 0.05). "Functional limitation," "physical pain," "physical disability," and "psychological disability" scores significantly decreased at T3, and "psychological discomfort" scores also significantly dropped at T2. "Social disability" and "handicap" scores remained unchanged throughout. CONCLUSION: Fixed definitive prostheses with metal framework are more effective than fixed all-acrylic prostheses in improving OHRQoL during All-on-4(®) treatment.

Double Full-Arch Versus Single Full-Arch, Four Implant-Supported Rehabilitations: A Retrospective, 5-Year Cohort Study.

PURPOSE: To report the 5-year outcome of the All-on-4 treatment concept comparing double full-arch (G1) and single-arch (G2) groups. MATERIALS AND METHODS: This retrospective cohort study included 110 patients (68 women and 42 men, average age of 55.5 years) with 440 NobelSpeedy groovy implants. One hundred sixty-five full-arch, fixed, immediately loaded prostheses in both jaws were followed for 5 years. G1 consisted of 55 patients with double-arch rehabilitations occluded with implant-supported fixed prostheses, and G2 consisted of 55 patients with maxillary single-arch rehabilitations or mandibular single-arch rehabilitations occluded with natural teeth or removable prostheses. The groups were matched for age (±6 years) and gender. Primary outcome measures were cumulative prosthetic (both interim and definitive) and implant survival (Kaplan-Meier product limit estimator). Secondary outcome measures were marginal bone levels at 5 years (through periapical radiographs and using the patient as unit of analysis) and the incidence of mechanical and biological complications. Differences in survival curves (log-rank test), marginal bone level (Mann-Whitney U test), and complications (chi-square test) were compared inferentially between the two groups using the patient as unit of analysis with significance level set at p ≤ 0.05. RESULTS: No dropouts occurred. Prosthetic survival was 100%. Five patients lost 5 implants (G1: n = 3; G2: n = 2) before 1 year, rendering an estimated cumulative survival rate of 95.5% (G1: 94.5%; G2: 96.4%; Kaplan-Meier, p = 0.645, nonsignificant). The average (SD) marginal bone level was 1.56 mm (0.89) at 5 years [G1: 1.45 mm (0.77); G2: 1.67 mm (0.99); p = 0.414]. The incidence rate of mechanical complications (in both interim and definitive prostheses) was 0.16 and 0.13 for G1 and G2, respectively (p = 0.032). The incidence rate of biological complications was 0.06 and 0.05 for G1 and G2, respectively (p = 0.669). CONCLUSIONS: Based on the results, rehabilitating double- or single-arch edentulous patients did not yield significant differences on survival curves. The incidence of mechanical complications was significantly higher for double-arch rehabilitated patients but nevertheless, these mechanical complications did not affect the long-term survival of either the prostheses or the implants.