Edentulous Posterior Mandible Research Articles

Mandibular Fixed Prosthesis With A 3d-Printed Subperiosteal Implant: A Case Report.

This case report aims to present the successful restoration of the atrophic partially edentulous posterior mandible using custom-made subperiosteal implants. The fixed prosthesis restoration was achieved using CAD-CAM technologies and 3D metal printing methods. The partially edentulous 58-year-old patient expressed a preference not to undergo bone augmentation procedures. The patient with teeth in the anterior mandible was treated with two separate custom-made subperiosteal implants. A custom-made prosthesis was fabricated from sintered titanium using machined subperiosteal implants with a universal external connection. Subperiosteal implants offer several advantages over conventional bone grafting plus intraosseous implant placement techniques, such as the simple, one-step procedure for atrophic jaws, streamlining the treatment process and reducing the overall time involved. Treatments using subperiosteal implants can be an alternative solution for individuals with severely atrophic jaws. Longer-term studies in a larger sample are warranted to corroborate previous reports.

Effect of bone mass density and alveolar bone resorption on stress in implant restoration of free-end edentulous posterior mandible: Finite element analysis of double-factor sensitivity

BackgroundOsseous condition of the mandible was regarded as a key factor influencing stability of implants in the early stage. Finite element analysis was used to assess the effect of bone mass density and alveolar bone resorption (double factors) on stress in a four-unit implant restoration of a free-end edentulous posterior mandible. MethodsA 3D finite element model was constructed for a single-sided free-end edentulous mandible (from mandibular first premolar to mandibular second molar) containing threaded dental implants. Mandible sensitivity modes were constructed with different alveolar bone resorption levels for normal conditions as well as mild, moderate and severe periodontitis, respectively. Based on the mass density of cancellous bone for four types of bones as the sensitivity parameter, two implant design modes were constructed: Model A (four-unit fixed bridge supported by three implants, implant positions were 34, 36 and 37) and model B: 34 × 36, 37 (37: a single implant crown) (34 × 36: three-unit fixed bridge supported by two implants, implant positions were 34 and 36). A total of 32 sensitivity-based finite element models, grouped in two groups, were constructed. Stress distribution and maximum von Mises stress on cortical bone and cancellous bone around the implant, as well as the surface of implant were investigated by using ABAQUS when vertical loading and 45° oblique loading were applied, respectively. ResultsWhen vertical loading was applied on the implant, maximum von Mises stress on the cortical bone around the implant was assessed to be 4.726 MPa - 13.15 MPa and 6.254 MPa - 13.79 MPa for groups A and B, respectively; maximum stress on the cancellous bone around the implant was 2.641 MPa - 3.773 MPa and 2.864 MPa - 4.605 MPa, respectively; maximum stress on the surface of implant was 14.7 MPa - 21.17 MPa and 21.64 MPa - 30.70 MPa, respectively. When 45° oblique loading was applied on the implant restoration, maximum von Mises stress on the cortical bone around the implant was assessed to be 42.08 MPa - 92.71 MPa and 50.84 MPa - 102.5 MPa for groups A and B, respectively; maximum stress on the cancellous bone around the implant was 4.88 MPa - 25.95 MPa and 5.227 MPa - 28.43 MPa, respectively; maximum stress on the surface of implant was 77.91 MPa - 124.8 MPa and 109.2 MPa - 150.7 MPa, respectively. Stress peak on the cortical bone and that on cancellous bone around the implant increased and decreased with the decrease in bone mass density, respectively. Stress peak on alveolar bone increased with alveolar bone resorption when oblique loading was applied. Conclusion1. Both alveolar bone resorption and bone mass density (double factors) are critical to implant restoration. Bone mass density may exhibit a more pronounced impact than alveolar bone resorption. 2. From the biomechanical perspective, types I and II bones are preferred for implant restoration, while implantation should be considered carefully in the case of type III bones, or those with less bone mass density accompanied by moderate to severe alveolar bone loss. 3. Splinting crowns restoration is biomechanically superior to single crown restoration.

A Retrospective Study of Implant Placement Lateral to the Inferior Alveolar Nerve (ILIAN) in Severely Atrophic Posterior Mandibular Ridges

Currently, there are several techniques being used in the posterior mandible to increase alveolar bone height and width. However, each of these has potential complications and limitations. The purpose of the current study was to present the surgical technique and restorative considerations for implant placement lateral to the inferior alveolar nerve (IAN) in cases of severely atrophic edentulous posterior mandibles. In the current study, 26 implants in 16 patients were successfully placed lateral to IAN and restored with splinted screw-retained prostheses with a follow-up time after loading ranging from 3 months to 6 years. Two patients reported complications. One patient had a temporary paresthesia that resolved 3 months after implant placement and the second patient had minor paresthesia which was reduced after implant removal but remained in a small area on the left corner of her lip.

P-67954085-235 - A new classification of inferior alveolar nerve repositioning procedure for dental implants placement presentation and illustrative cases.

<h3>Objectives</h3> Tooth loss is one of the most common causes of reduced quality of life in adults. Recently there is an increasing global interest in treatments involving the Inferior Alveolar Nerve (IAN) repositioning for dental placement but standardization and classification of the techniques is warranted. In the present paper, a new classification is suggested, illustrated, and discussed. <h3>Patients and Methods</h3> A retrospective analysis of the preoperative radiographic records and the documents of the surgical procedures during a ten year period between 2008 -2018 of patients who had been treated with implant placement in conjunction with IAN repositioning of posterior atrophic mandible was performed. The cases were categorized according to the available bone, the nerve location, and the surgical intervention into four groups. <h3>Results</h3> Overall, 132 edentulous posterior mandibles in 98 patients (72 women, 26 men; age range 20-75 years) were included in the analysis. Those sites were divided into four categories: Category 1, included 54 patients with 72 sites, and was treated by one surgery. Category 2; included 15 patients with 15 sites and was treated with two stages. Category 3, included 17 patients with 21 sites, and category 4, included 12 patients with 24 sites. The treated 132 sites with IAN repositioning received 379 dental implants. All the sites were restored by an implant-supported fixed prosthesis. The patients reported good function and improvement in their quality of life. <h3>Conclusions</h3> This new classification might enhance diagnosis and help predict the treatment stages of the patients requiring IAN repositioning for dental implant placement.

To evaluate and compare the effect of stresses in peri implant bone after offset placement of implant in edentulous posterior mandible using

Background: In the present era, when it comes to oral rehabilitation, a wide array of options are available to restore missing teeth using fixed and removable prostheses, however, advances in dental implant surgery offer viable option to provide improved functional efficiency, appearance, comfort and speech2 . The desired position of the artificial teeth is determined by aesthetic and functional requirements. Lack of bone volume always results in exposure of implant surface, reduced bone implant contact and finally implant failure. Aim: The aim of this study is to evaluate and compare the effect of stresses in peri implant bone after offset placement of implant in edentulous posterior mandible using: - “3D finite element analysis (FEA).” Objectives: 1. To evaluate the effect of stresses in peri implant bone after offset placement of dental implant using 3D finite element analysis. 2. To analyze the stress distribution patterns in the implant and the peri implant bone interface. 3. To evaluate and compare the stress in peri implant bone after placing the implant in different implant configurations – straight and offset.

Experimental validation of a micro-CT finite element model of a human cadaveric mandible rehabilitated with short-implant-supported partial dentures

PurposeThis study aimed to address the predictive value of a micro-computed tomography (μCT)-based finite element (μFE) model of a human cadaveric edentulous posterior mandible, rehabilitated by short dental implants. Hereby, three different prosthetic/implant configurations of fixed partial dentures (“Sp”-3 splinted crowns on 3 implants, “Br” – Bridge: 3 splinted crowns on 2 implants, and “Si”- 3 single crowns) were analysed by comparing the computational predictions of the global stiffness with experimental data. MethodsExperimental displacement of the bone/implant/prosthesis system was measured under axial and oblique loads of 100 N using an optical deformation system (GOM Aramis) and the overall movement of the testing machine (Zwick Z030). Together with the measured machine force, an “Aramis” (optical markers) and “Zwick” (test machine) stiffness were calculated. FE models were created based on μCT-scans of the cadaveric mandible sample (n = 1) before and after implantation and using stl-files of the crowns. The same load tests and boundary conditions were simulated on the models and the μFE-results were compared to experimental data using linear regression analysis. ResultsThe regression line through a plot of pooled stiffness values (N/mm) for the optical displacement recording (true local displacement) and the test machine (machine compliance included) had a slope of 0.57 and a correlation coefficient R2 of 0.82. The average pooled correlation of global stiffness between the experiment and FE-analysis (FEA) showed a R2 of 0.80, but the FEA-stiffness was 7.2 times higher. The factor was highly dependent on the test configuration. Sp-configuration showed the largest stiffness followed by Br-configuration (17% difference in experiment and 21% in FEA). ConclusionsThe current study showed good qualitative agreement between the experimental and predicted global stiffness of different short implant configurations. It could be deduced that 1:1 splinting of the short implants by the crowns is most favorable for the stiffness of the implant/prosthesis system. However, in the clinical context, the absolute in silico readings must be interpreted cautiously, as the FEA showed a considerable overestimation of the values.

Clinical comparison of different flap advancement techniques to periosteal releasing incision in guided bone regeneration: A randomized controlled trial.

To compare Double Flap Incision (DF), Coronally Advanced Lingual Flap (CALF), and Modified Periosteal Releasing Incision (MPRI) to Periosteal Releasing Incision (PRI) in flap advancement, postoperative complications in augmentation using titanium mesh. Forty patients with partially edentulous posterior mandibles were randomly assigned to the four groups. We evaluated: (a) Flap advancement in mm (Primary outcome). (b) Pain using the Numerical Rating scale (NRS). (c) Swelling using the Visual Analogue Scale (VAS). (d) Exposure in mm and exposure percentage at 1 week to 6 months. The CALF showed the highest mean flap advancement of 19.9 (±5.0) mm while the PRI showed the lowest; 10.2 (±1.7) mm. The difference between groups was statistically significant (P value <.0001). MPRI showed the highest pain score of 5.3 (±1.3) while the DF showed the lowest; 2.39 (±1.7). Swelling did not show a significant difference between groups. MPRI showed the highest exposure mean; 18.6 mm (±26.3) while CALF showed the lowest; 2.5 mm (±4.0). PRI showed the highest exposure percentage; 7.4% (±9.3) while CALF showed the lowest; 0.4% (±0.7). The difference between groups was insignificant. CALF reported highest advancement, least complications while PRI reported the highest complications.

CT-based dentulous mandibular alveolar ridge measurements as predictors of crown-to-implant ratio for short and extra short dental implants

The purpose was to predict the crown-to-implant ratio variation in the edentulous posterior mandibles rehabilitated with short dental implants. Hence, vertical and horizontal dimensions of dentulous posterior mandibles in a sample of 18- to 25-year-olds were measured, and correlations of these dimensions with sex and site were investigated. Mandibular computed tomography scans from 100 subjects were considered. Vertical and horizontal bone and tooth measurements were taken at the sites of the second premolar (PM), and the mesial and distal roots of the first and second molars (M1m, M1d, M2m and M2d, respectively). A hypothetical crown-to-implant ratio (C/I R) was calculated assuming the insertion of short and extra short implants (5, 6 or 7 mm), at 1.5 mm from the inferior alveolar canal, maintaining the position of the existing occlusal plane. All vertical bone dimensions decreased from the PM to the M2d. Width measurements increased from the mesial (PM) to the distal sites (M1m, M1d, M2m and M2d). Males had significantly greater vertical and horizontal measurements than females at all sites. The mean C/I R was higher than 2 for all sizes of implant. The C/I R was lower for the second molar than for the second premolar, while it was similar for the first molar and the second premolar. Males had a higher C/I R than females. Computed tomography can be used to study the anatomical features of alveolar bone, and to predict some clinical aspects of prosthetic rehabilitation with implants, such as the crown-to-implant ratio in conditions of serious bone atrophy.

In-Block Lateralization as a New Technique for Mobilization of the Inferior Alveolar Nerve: A Technique Case Series.

The edentulous atrophic posterior mandible is often a great challenge for implant rehabilitation. Although a number of treatment options have been proposed, including the use of short implants and surgical grafting techniques, in cases of severe bone atrophy, techniques for mobilization of the inferior alveolar nerve (IAN) have been shown to be efficient, with good results. Four female patients underwent IAN lateralization for prosthetic rehabilitation of the posterior mandible from 2013 to 2019, with 3 years to 5 years and 3 months of follow-up. This case series describes a new technique for mobilization of the IAN, named in-block lateralization, to facilitate access to the IAN and to reduce nerve manipulation. The implant is immediately installed (allowing nerve lateralization in unitary spaces), and the original mandibular anatomy is restored with autogenous bone from the original bed during the same surgical procedure. When well indicated and well performed, this new approach provides better and easier visualization of the IAN and safer manipulation aiming to achieve good results for implant stability and minimal risk of neurosensory disturbances, allowing rehabilitation even in unitary spaces.

Immediate Loading of Fixed Partial Dental Prostheses on Extra-Short and Short Implants in Patients with Severe Atrophy of the Posterior Maxilla or Mandible: An Up-to-4-year Clinical Study.

The goal of this study was to evaluate the cumulative survival rate and marginal bone loss (MBL) of extra-short (5- and 6-mm-long) and short (6.5-mm-long) implants inserted into severely atrophic, partially edentulous posterior maxillae and mandibles that were immediately restored with provisional fixed dental prostheses. Between October 2013 and December 2017, partially edentulous patients with severe vertical bone atrophy in the posterior area in need of replacement of premolars and/or molars with fixed prostheses were enrolled in the study. Analysis of cumulative survival rate and MBL was determined with respect to implant length at the longest, biannual follow-up period (38 ± 10 months; range: 25 to 48 months). Fifty-five patients were included in the study. A total of 62 extra-short (5 and 6 mm), 15 short (6.5 mm), and 69 standard-length (≥ 10 mm) implants were immediately placed and loaded. Cumulative survival rates were similar for all implants (99.3%). One mandibular extra-short implant failed and was removed but was replaced 2 months later with another implant of the same length and diameter and successfully reloaded. Implant length did not impart any significant differences in MBL, though the presence or absence of platform switching was influential. The cumulative survival rate and MBL reported in this study encourage the use of short and extra-short implants to immediately restore with fixed prostheses partially edentulous patients with severe vertical bone atrophy in posterior areas. Thus, it could be an alternative treatment to vertical bone augmentation.

Bone Loss in the Posterior Edentulous Mandible with Implant-Supported Overdentures vs Complete Dentures: A Systematic Review and Meta-Analysis.

To analyze the current evidence on bone loss in the posterior edentulous mandible restored with complete dentures (CDs), two-implant-supported overdentures (2-IODs), or four-implant-supported overdentures (4-IODs). A search was conducted in the Ovid MEDLINE, Embase, Web of Science, CINAHL, and Cochrane databases for clinical studies comparing bone loss in posterior edentulous mandibles restored with CDs, 2-IODs, or 4-IODs. A meta-analysis was performed using statistical software to estimate the mean differences in bone loss with 95% CI. The level of significance was set at P < .05. The search strategy identified 2,806 articles, of which 14 met the inclusion criteria. The meta-analysis included 7 two-arm studies comparing CDs vs 2-IODs or 2-IODs vs 4-IODs. No statistically significant difference was found in bone loss between 2-IODs and CDs (mean difference -0.25 [95% CI -0.85 to 0.36]; P = .43), whereas bone loss was significantly lower with 4-IODs than with 2-IODs (mean difference -0.96 [95% CI -1.86 to -0.06]; P = .04). Overall, the data were highly heterogenous (I2 > 74%). 4-IODs can benefit the patient by decreasing bone loss in the posterior edentulous mandible. However, 2-IODs may not be superior to CDs in reducing bone loss in the posterior mandible. A validation of these results is needed through well-designed RCTs.

Evaluation of Different Heights of Prosthetic Crowns Supported by an Ultra-Short Implant Using Three-Dimensional Finite Element Analysis.

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. 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. 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. 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.

Influence of Resonance Frequency Analysis (RFA) Measurements for Successful Osseointegration of Dental Implants During the Healing Period and Its Impact on Implant Assessed by Osstell Mentor Device.

AIM:This study aimed to investigate and assess primary and secondary dental implant stability during the osseointegration period.METHODS:A total of 77 implants were placed in 42 patients with 26 males and 16 females. The study was conducted by comparing the resonance frequency analysis (RFA) values of the implants inserted in the lower jaw. RFA was done immediately after implant insertion and after 12 weeks. Results were statistically evaluated using SPSS Statistics for Windows, Version 7.1. Level of significance was set at P < 0.05.RESULTS:Significant differences were detected between the primary and secondary stability values, respectively. Maximum RFA value of 88 and the minimum value of 52 were observed. Stability values increased during the following three months, and all implants were successfully integrated without complication.CONCLUSION:Our results indicate and suggest that there is a strong linear correlation between implant stability and ISQ values that can be directly estimated by the RFA, especially in the posterior edentulous mandible. Osstell implant device could represent a useful tool which can be used to identify the risk for implant failure.

In vitro digital image correlation analysis of the strain transferred by screw-retained fixed partial dentures supported by short and conventional implants

PurposeThis study used digital image correlation (DIC) to evaluate the strain transferred by splinted and non-splinted screw-retained fixed partial dentures (FPDs) supported by short and conventional implants. Material and methodsFour polyurethane models were fabricated to simulate half of the mandibular arch with acrylic resin replicas of the first premolar. Short (5 mm) and/or conventional (11 mm) implants replaced the second premolar and the first and second molars. Groups were: G1, two conventional (second premolar and first molar) and one short (second molar) implant; G2, one conventional (second premolar) and two short (first and second molar) implants; G3, three short implants; and G4, three conventional implants. Splinted (S) and non-splinted (NS) FPDs were screwed to the implant abutments. Occlusal load and a single point load on the second premolar, both of 250 N, were applied. Strain in the horizontal direction (Ɛxx) was calculated and compared using the DIC software. ResultsSplinted crowns presented the highest strain magnitudes of all tested groups (p < 0.05). The strain was concentrated near the short implants and presented a higher magnitude compared to conventional implants, especially in G2S (−560.13 μS), G3S (−372.97 μS), and G4S (−356.67 μS). ConclusionsSplinted crowns presented a higher strain concentration around the implants, particularly near the implant replacing the first molar. A combination of short and conventional implants seems to be a viable alternative for the rehabilitation of the posterior edentulous mandible with reduced bone height.

Evaluation of Alveolar Ridge Height Gained by Vertical Ridge Augmentation Using Titanium Mesh and Novabone Putty in Posterior Mandible.

The purpose of this case series was to report the clinical and radiographical outcomes of vertical ridge augmentation in edentulous posterior mandible using a combination of titanium mesh with novabone putty. Twenty patients were included, and grafting was done using alloplastic novabone putty supported by titanium mesh as the barrier for guided bone regeneration. Sixteen patients exhibited good soft tissue healing. Postoperative flap dehiscence occurred relatively early in the healing period in one patient followed by graft extrusion and delayed healing in other three patients. The mean vertical height of augmented bone was 4.825 ± 1.1387mm. This report demonstrates the remarkable efficacy of guided bone regeneration using a combination of titanium mesh and novabone putty for vertical ridge augmentation, thus expanding the indications for implant therapy and allowing recovery of the three-dimensional esthetic architecture in a severely resorbed alveolar ridge.

Efeitos da desinfecção e da des/reconexão dos pilares nos tecidos peri-implantares: um ensaio clínico randomizado

Objetivo: Avaliar clinicamente (profundidade de sondagem, índice de sangramento gengival, índice de placa, recessão da margem mucosa vestibular) e radiograficamente (perda óssea) os efeitos das sucessivas des/reconexões e dos procedimentos químicos e mecânicos para desinfecção dos pilares de cicatrização em um ensaio clínico randomizado. Material e Métodos: Seis implantes com conexão de hexágono externo (4,1 mm Ø) e seus pilares de cicatrização foram instalados nas regiões posteriores edêntulas da mandíbula de 11 pacientes. Três meses após a cirurgia, cinco pilares de cicatrização foram desconectados uma vez ao mês, durante 5 meses, e tratados de diferentes maneiras (imersão em: solução de álcool 70%; solução de clorexidina 0,12%; jateamento com solução de bicarbonato de sódio; deixada exposta ao ar; substituído por outro novo), e um pilar de cicatrização não foi desconectado; totalizando 6 grupos diferentes de 11 pilares de cicatrização. Os examinadores foram calibrados antes da avaliação e eram cegos. Resultados: Os diferentes tratamentos dos pilares de cicatrização não resultaram em diferenças estatisticamente significantes para nenhum dos parâmetros avaliados (P&gt;0.05). As sucessivas des/reconexões não resultaram em diferenças estatisticamente significativas em comparação com o grupo controle (P&gt;0.05). Conclusão: O tratamento dos pilares de cicatrização e o número de des/reconexões realizadas não tiveram efeitos significantes nos tecidos peri-implantares, pelo menos, 6 meses após a des/reconexão inicial.

Ultra-Short Implants for Rehabilitation of the Edentulous Posterior Mandible: Outcomes after 2 Years

Ultra-Short Implants for Rehabilitation of the Edentulous Posterior Mandible: Outcomes after 2 Years

Short Versus Longer Implants in Mandibular Alveolar Ridge Augmented Using Osteogenic Distraction: One-Year Follow-up of a Randomized Split-Mouth Trial.

The aim of this study was to evaluate the reliability of 6-mm-long implants compared with normal-length implants placed in a vertical augmented atrophic posterior mandible, supporting cemented single crowns. Thirty-six patients with bilateral posterior edentulous mandible and presenting a bone availability height less than 9 mm from the mandibular canal were enrolled in this study. Patient hemiarches were randomized to receive both 6-mm-long and normal-length implants (10 mm). The technique used for the vertical bone augmentation was the "sandwich" technique, using a bone substitute block as graft. The data outcomes at 1 year postloading follow-up were the loss of implants and complications. Eighty-six 6-mm-long implants and 84 normal implants were inserted. Five short implants and 13 normal implants were lost. In 28 patients, complications occurred, and in 21 cases, the complication was present on the side of the ridge vertical augmentation. From the statistical analysis, the association between the side of the ridge augmentation and the side of occurrence of the complication was statistically significant ( P < .05). The results from this trial suggest short implants can be preferred over vertical bone augmentation for the placement of longer implants in the rehabilitation of edentulous posterior mandibles. These initial results must be confirmed by larger and longer follow-ups of 5 years or more.

Influence of Bisphosphonates on Implant Failure Rates and Characteristics of Postmenopausal Woman Mandibular Jawbone.

Rehabilitation of oral function using dental implants is clinically effective and highly predictable. Both bone quantity and quality at the implant site affect the success of the procedure. However, the effect of bisphosphonate (BP) use on mandibular bone quality has not been well documented. The purpose of this retrospective cohort study was to evaluate the bone mineral density (BMD) and cortical thickness of the mandible, as well as the influence of BP use on early implant failure. Twenty-five female patients (≥60 years of age) were selected from among 93 candidates with partially edentulous posterior mandibles. Eleven patients had received BP therapy using alendronate (BP group), and 14 patients had received alternate therapy (non-BP group). Cortical and trabecular BMD was measured using quantitative computed tomography. Cortical thickness was measured using computed tomography. The BMDs and cortical thicknesses of the two groups were compared. The results were as follows: (1) Cortical BMD was significantly higher in the BP group, (2) trabecular BMD was not affected by BP use, and (3) Cortical thickness was affected by the duration of BP use. These results indicate that BP use affects the quality and quantity of the cortical bone in the partially edentulous posterior mandible of patients with osteoporosis, which should be considered prior to treatment with dental implants in patients taking BPs.

Biomechanical effects of offset placement of dental implants in the edentulous posterior mandible.

BackgroundProper implant placement is very important for long-term implant stability. Recently, numerous biomechanical studies have been conducted to clarify the relationship between implant placement and peri-implant stress. The placement of multiple implants in the edentulous posterior mandible has been studied by geometric analysis, three-dimensional finite element analysis (FEA), model experimentation, etc. Offset placement is a technique that reduces peri-implant load. However, few studies have used multiple analyses to clarify the value of the offset placement under identical conditions.The present study aimed to clarify the biomechanical effects of offset placement on the peri-implant bone in edentulous posterior mandibles by comparative investigation using FEA and model experimentation with strain gauges.MethodsThree implants were embedded in an artificial mandible in the parts corresponding to the first premolar, the second premolar, and the first molar. A titanium superstructure was mounted to prepare models (experimental models). Three load points (buccal, central, and lingual) were established on the part of the superstructure corresponding to the first molar. Three types of experimental models, each with a different implant placement, were prepared. In one model, the implants were placed in a straight line; in the other two, the implants in the parts corresponding to the second premolar and the first molar were offset each by a 1-mm increment to the buccal or lingual side. Four strain gauges were applied to the peri-implant bone corresponding to the first molar.The experimental models were imaged by micro-computed tomography (CT), and FEA models were constructed from the CT data. A vertical load of 100 N was applied on the three load points in the experimental models and in the FEA models. The extent of compressed displacement and the strain in the peri-implant bone were compared between the experimental models and the FEA models.ResultsBoth experimental and FEA models suffered the least compressed displacement during central loading in all placements. The greatest stress and compressive strain was on the load side in all types of placements.ConclusionsOffset placement may not necessarily be more biomechanically effective than straight placement in edentulous posterior mandibles.