Mandibular movements in older people with rheumatoid arthritis.

OBJECTIVE: The aim of this study was to compare the mandibular movements in older people with and without temporomandibular disorder (TMD) associated with rheumatoid arthritis (RA). STUDY DESIGN: Thirty partially or completely edentulous older adults (65.33 ± 4.7 years) were assigned to 2 groups: (1) with RA and TMD and (2) without RA and TMD. Chewing movements of the jaws during mastication of the test material (Optocal) and the range of mandibular movements were evaluated by using the JT-3-D kinesiographic device before and after new removable prosthesis insertion. Multiple comparisons were made with analysis of variance (ANOVA) and the Tukey-Kramer test. RESULTS: Comparisons between the 2 groups before and after new prosthesis insertion revealed that the RA and TMD group had reduced opening angles (P < .05) during chewing. After insertion of new prostheses, both groups showed increased opening and closing angles during chewing (P < .05). The mandibular range of motion results showed that patients with RA and TMD exhibited lower aperture and laterality movements (P < .05) compared with controls before and after new prosthesis insertion. However, there was an increase in aperture, lefty laterality, and protrusion values after new prosthesis insertion in both groups. CONCLUSIONS: TMD associated with RA may impair mandibular movements. Well-fitted prostheses may improve mandibular movements in older adults, especially those with RA.

Single mandibular implant study - denture satisfaction in the elderly.

To investigate whether there are differences in patients' denture satisfaction when an implant placed in the midline of the edentulous mandible is loaded either immediately or three months later, after second-stage surgery. One hundred and fifty-eight edentulous patients received a single implant in the midline of the mandible. After randomisation, it was loaded either immediately after implant placement (N = 81, group A) or three months later, after a submerged healing phase and a second-stage surgery (N = 77, group B). Patients' denture satisfaction aspects were assessed, using visual analogue scales (VAS), before treatment, one month after implant placement during the submerged healing phase (only group B) and one and four months after implant loading. The statistical analysis was performed using the Wilcoxon signed-rank and rank-sum tests. One month after loading, a significant improvement in comfort, function and stability of the mandibular denture could be observed in both groups (P ≤ 0·05). A slight but not significant improvement was found between one and four months after loading. Patients with second-stage surgery and delayed loading rated the stability and fit of the mandibular denture as significantly better than patients who had immediate loading. A single implant in the edentulous mandible significantly increased patients' denture satisfaction. After four months, stability and fit of the mandibular denture were considered better when a delayed loading protocol had been followed. A single mandibular implant in the edentulous mandible significantly increases patients' denture satisfaction, regardless of the loading protocol.

Mucosal Manifestations in the Edentulous Maxilla with Implant Supported Prostheses: Clinical Results from a Well-Maintained Patient Cohort.

BACKGROUND: Prostheses in the edentulous maxilla affect the mucosa. PURPOSE: To evaluate mucosal alterations with implant supported fixed prostheses (FDP) and overdentures (IOD). MATERIAL AND METHODS: Patients receiving prostheses during a time period of 10 years were recruited. Maxillary mucosal conditions in relation to FDPs, IODs were analyzed. Peri-implant parameters were measured and the Oral Health Impact Profile (OHIP) was administered. RESULTS: One hundred seven patients wearing 74 IODs and 33 FDPs were identified with a total of 519 implants, the mean observation time was 6.5 ± 2.7. Cumulative implant survival was 93%. Erythema and hyperplastic tissue were identified in 71% of the IOD wearers, but were mostly absent with FDPs. The peri-implant parameters demonstrated healthy peri-implant mucosa. Medication and smoking had no effect on mucosal alteration (OR = 1.065 and 1.568). The average OHIP value was 3.73 ± 4.12. A lower value (p < 0.0048) was found for FDPs and one type of IOD. CONCLUSIONS: A rigorous maintenance program did not prevent IOD mucosal alterations in IOD wearers, but the health of the peri-implant mucosa was maintained and was comparable for all types of prostheses.

Stability of edentulous, atrophic mandibles after insertion of different dental implants. A biomechanical study.

OBJECTIVES: Fractures of the atrophic edentulous mandible are a rare complication that can become severe after the insertion of dental implants. This in vitro study investigated the effects of different implant settings varying in number, diameter, and length. and the influence of a fixed bar. MATERIALS AND METHODS: In biomechanical experiments on artificial mandibles, an unmodified reference group, four implant settings with two different implants, and the effect of adding a fixed bar to these settings were tested. All specimens were loaded with incisal biting forces until failure due to fracture. RESULTS: Implants weakened all specimens significantly compared with those in the reference group. Without a fixed bar, four short and thick implants showed the best results, with high significance. With a fixed bar, four long and thin implants withstood the highest loads. The addition of fixed bars reduced the differences between the implant settings. Fixed bars did not show increased stability for all groups; however, these groups showed a higher mean strength. CONCLUSIONS: Four implants with a short and thick design should be the first choice when implants are placed without a fixed bar in an atrophic mandible. With a fixed bar, four long and thin implants should be used.

Finite-element analysis of 3 situations of trauma in the human edentulous mandible.

PURPOSE: Maxillofacial trauma resulting from falls in elderly patients is a major social and health care concern. Most of these traumatic events involve mandibular fractures. The aim of this study was to analyze stress distributions from traumatic loads applied on the symphyseal, parasymphyseal, and mandibular body regions in the elderly edentulous mandible using finite-element analysis (FEA). MATERIALS AND METHODS: Computerized tomographic analysis of an edentulous macerated human mandible of a patient approximately 65 years old was performed. The bone structure was converted into a 3-dimensional stereolithographic model, which was used to construct the computer-aided design (CAD) geometry for FEA. The mechanical properties of cortical and cancellous bone were characterized as isotropic and elastic structures, respectively, in the CAD model. The condyles were constrained to prevent free movement in the x-, y-, and z-axes during simulation. This enabled the simulation to include the presence of masticatory muscles during trauma. Three different simulations were performed. Loads of 700 N were applied perpendicular to the surface of the cortical bone in the symphyseal, parasymphyseal, and mandibular body regions. The simulation results were evaluated according to equivalent von Mises stress distributions. RESULTS: Traumatic load at the symphyseal region generated low stress levels in the mental region and high stress levels in the mandibular neck. Traumatic load at the parasymphyseal region concentrated the resulting stress close to the mental foramen. Traumatic load in the mandibular body generated extensive stress in the mandibular body, angle, and ramus. CONCLUSIONS: FEA enabled precise mapping of the stress distribution in a human elderly edentulous mandible (neck and mandibular angle) in response to 3 different traumatic load conditions. This knowledge can help guide emergency responders as they evaluate patients after a traumatic event.

Finite element analysis of provisional structures of implant-supported complete prostheses.

The use of provisional resin implant-supported complete dentures is a fast and safe procedure to restore mastication and esthetics of patients soon after surgery and during the adaptation phase to the new denture. This study assessed stress distribution of provisional implant-supported fixed dentures and the all-on-4 concept using self-curing acrylic resin (Tempron) and bis-acrylic resin (Luxatemp) to simulate functional loads through the three-dimensional finite element method. Solidworks software was used to build three-dimensional models using acrylic resin (Tempron, model A) and bis-acrylic resin (Luxatemp, model B) for denture captions. Two loading patterns were applied on each model: (1) right unilateral axial loading of 150 N on the occlusal surfaces of posterior teeth and (2) oblique loading vector of 150 N at 45°. The results showed that higher stress was found on the bone crest below oblique load application with a maximum value of 187.57 MPa on model A and 167.45 MPa on model B. It was concluded that model B improved stress distribution on the denture compared with model A.

Biomechanical effect of crestal bone osteoplasty before implant placement: a three-dimensional finite element analysis.

This study investigated the biomechanical effects of crestal bone osteoplasty and flattening procedures carried out in edentulous knife-edge ridges to restore bone width before implant placement on the virtually placed implants using finite element methods. Three-dimensional models representing a knife-edged alveolar bone with two different crestal cortical bone thicknesses (1.6mm, thin group; 3.2mm, thick group) were created. Gradual crestal bone osteoplasty with 0.5mm height intervals was simulated. Cylindrical implants with abutments and crowns were constructed and subjected to oblique loads. Maximum stress was observed at the cervical region around the implant neck. Different osteoplasty levels showed different stress values and distributions. Highest compressive stress was observed in the flat models (60.8 MPa and 98.3 MPa in thick and thin groups, respectively), lowest values were observed when osteoplasty was limited to the sharp edge (36.8 MPa and 38.9 MPa in thick and thin groups, respectively). The results suggested that eliminating the sharp configuration in knife-edge ridges improved stress and strain outcomes, but flattening the alveolar crest and/or uncovering the cancellous bone resulted in a marked increase in compressive stress and strain values in the peri-implant bone that may influence the longevity of implants placed in these ridges.

The effect of mandibular denture abstention on masseter muscle thickness in a 97-year-old patient: a case report.

This case report describes the effect of complete denture abstention and subsequent rehabilitation with mandibular implant-supported overdentures (IOD) on masseter muscle thickness (MMT) in a 97-year-old patient. MMT was measured bilaterally using an ultrasound scanner during 1 year of wearing a conventional denture, after 101 days of voluntary denture abstention, and 3, 6, and 12 months after delivery of the IOD. MMT decreased by 17% during denture abstention following repeated implant surgery, and returned to 100% during the 12 months with the mandibular IOD. This case suggests that muscle bulk may be related to denture function.

Edentulism and fruit and vegetable intake in low-income adults.

Poor dental status negatively relates to dietary intakes. However, this issue has not been researched among the most vulnerable groups in society. We aimed to investigate, in a national low-income sample, the association between dental status and fruit and vegetable consumption. We analyzed data on adults aged 50 years and older from the Low Income Diet and Nutrition Survey, a representative sample of deprived UK households. Considerable numbers reported difficulty eating specific foods, with significantly worse experience among edentate than dentate people. The mean daily fruits and vegetables consumption was low (256.5 g for dentate, 207.1 g for edentate). After adjustment for socio-demographic and behavioral variables, edentate individuals consumed 50.7 g (27.0, 74.3) fewer fruits/vegetables per day than the dentate. Over and above the effects of material deprivation on nutrient intake, edentulism negatively relates to eating fruits and vegetables and achieving a healthy diet in materially deprived older adults.

Elastic properties and apparent density of human edentulous maxilla and mandible.

The aim of this study was to determine whether elastic properties and apparent density of bone differ in different anatomical regions of the maxilla and mandible. Additional analyses assessed how elastic properties and apparent density were related. Four pairs of edentulous maxilla and mandibles were retrieved from fresh human cadavers. Bone samples from four anatomical regions (maxillary anterior, maxillary posterior, mandibular anterior, mandibular posterior) were obtained. Elastic modulus (EM) and hardness (H) were measured using the nano-indentation technique. Bone samples containing cortical and trabecular bone were used to measure composite apparent density (cAD) using Archimedes' principle. Statistical analyses used repeated measures ANOVA and Pearson correlations. Bone physical properties differed between regions of the maxilla and mandible. Generally, mandible had higher physical property measurements than maxilla. EM and H were higher in posterior than in anterior regions; the reverse was true for cAD. Posterior maxillary cAD was significantly lower than that in the three other regions.

Correlations between physical properties of jawbone and dental implant initial stability.

STATEMENT OF PROBLEM: There is confusion in the literature about how physical properties of bone vary between maxillary and mandibular regions and which physical properties affect initial implant stability. PURPOSE: The purpose of this study was to determine correlations between physical properties of bone and initial implant stability, and to determine how physical properties and initial stability vary among regions of jawbone. MATERIAL AND METHODS: Four pairs of edentulous maxillae and mandibles were retrieved from fresh human cadavers. Six implants per pair were placed in different anatomical regions (maxillary anterior, right and left maxillary posterior, mandibular anterior, right and left mandibular posterior). Immediately after surgery, initial implant stability was measured with a resonance frequency device and a tapping device. Implant surgeries and initial stability measurements were performed within 72 hours of death. Elastic modulus (EM) and hardness were measured using nano-indentation. Composite apparent density (cAD) was measured using Archimedes' principle. Bone-implant contact percentage and cortical bone thickness were recorded histomorphometrically. Mixed linear models and univariate-correlation analyses were used (alpha=.05). RESULTS: Generally, mandibular bone had higher initial implant stability and physical properties than maxillary bone. Initial implant stability was higher in the anterior region than in the posterior. EM was higher in the posterior region than in the anterior; the reverse was true for cAD. CONCLUSIONS: Of the properties evaluated, cAD had the highest correlation with initial implant stability (r=0.82). Both physical properties of bone and initial implant stability differed between regions of jawbone.

Comparison of the effect of ovariectomy on bone mass in dentate and edentulous mandibles of adult rats.

We investigated the effect of ovariectomy (OVX) on bone changes in the edentulous and dentate mandibles and compared these to changes in tibiae and femorae using dual energy x-ray absorptiometry (DEXA) and histomorphometric measurements. One hundred and fifteen female rats had their molars and the incisor on one side of the mandible extracted at six months of age and allowed to heal for 4 months. At 10 months of age, animals were divided into an experimental group, which underwent bilateral ovariectomy, and a control group of intact animals. Sixteen OVX and sixteen control animals were sacrificed at 6-weeks, and at 6- and 9-months post-OVX. In addition 12 animals were sacrificed at the time of OVX to act as an internal control group. Bone mineral density measurements (BMD) using DEXA and bone volume measurements on undecalcified sections evaluated under backscattered electron microscopy were investigated in the edentulous and dentate mandibles as well as in tibiae and femorae. At 6-weeks post-OVX, there were no significant differences between the edentulous mandibles, dentate mandibles, tibiae and femorae of OVX and control groups. At 6 months post-OVX, BMD and cancellous bone volume were significantly decreased in the edentulous mandibles (-15.9%; -21.8%), proximal tibiae (-15.6%; -38.5%) and proximalfemorae (-9.7%; -39.6%) of OVX group as compared to the control group. At 9 months post-OVX, BMD and cancellous bone volume were further decreased in the edentulous mandibles (-17.2%; -24%), proximal tibiae (-16.1%; -58.9%) and proximal femorae (-10.3%; -49.9%) of the OVX group as compared to the control group. On the other hand, OVX had no effect on the BMD and cancellous bone volume of the dentate mandibles at 6-weeks and at 6- and 9-months post-OVX. These results show that loss of bone mass in the edentulous mandible of OVX animals is similar to that occurring in the tibiae and femorae, while lack of a significant effect of OVX on bone mass in the dentate mandible suggests that functional loading related to biting force prevented bone loss in the dentate mandible.

Ultrasound transmission velocity for noninvasive evaluation of jaw bone quality in vivo before dental implantation.

For the insertion of dental implants, mechanical bone properties at the implantation site have great impact both for therapeutic regimes as well as for the overall long-term success, making a reliable method for the preoperative assessment of the bone quality desirable. Ultrasound transmission velocity (UTV) has been introduced as a noninvasive method to analyze mechanical properties of bone. The aim of this study was the first intra-oral in vivo assessment of alveolar crest UTV values of edentulous jaws. Partly or fully edentulous patients (n = 108) were enrolled in this study, taking into account possible influence factors that affect bone quality (osteoporosis, radiation therapy). Six intra-oral measurement points were used: left side region, right side region and frontal region, for upper and lower jaw, respectively. Ultrasound transmission velocity values were measured bicortically (in bucco-oral direction) and correlated to sex, age, measurement site and history of osteoporosis or radiation therapy. We found a minimum mouth opening of 30 mm, as well as a residual alveolar ridge height of 8 mm as thresholds for a reliable intra-oral placement of the device. Xerostomia was no contraindication. Assessment of intra-oral UTV showed significantly higher values both for mandibular side regions (female 1713 +/- 153 m/s, male 1734 +/- 221 m/s) and the maxillary frontal region (female 1665 +/- 189 m/s, male 1648 +/- 82 m/s) than for maxillary side regions (female 1538 +/- 177 m/s, male 1583 +/- 90 m/s). These data were even more clarified by intra-individual correlation of upper and lower jaw side region UTV values. We found no correlation between assessed UTV values and the variables sex, age, osteoporosis or radiation therapy. The use of a small UTV device in this study allowed the recording of intra-oral UTV values in a large and heterogeneous patient collective for the first time. Assessment of alveolar-ridge UTV might offer the possibility to identify critical bone quality before implantation or to monitor bone healing (mineralization) after augmentation procedures.

Alveolar bone regeneration using absorbable poly(L-lactide-co-epsilon-caprolactone)/beta-tricalcium phosphate membrane and gelatin sponge incorporating basic fibroblast growth factor.

The aim of this study was to evaluate the effects of combining a porous poly(L-lactide-co-epsilon-caprolactone)/beta-tricalcium phosphate membrane and gelatin sponge incorporating basic fibroblastic growth factor (bFGF) on bone regeneration in mandibular ridges. Four full-thickness saddle-type defects (10 mm long x 5 mm deep) were symmetrically created in both edentulous mandibular alveolar ridges of 6 beagles. The dome-shaped membrane was secured to each defect site, and a gelatin sponge containing 200 microg bFGF was implanted on the left side of each defect (experimental group). Only the membranes (control group) were secured to the defect sites on the right. Three and 6 months later, 3 animals were killed. Bone regeneration was analyzed by soft X-ray photographs, micro-computed tomography (CT) images, and peripheral quantitative CT (pQCT), and then examined histologically. Soft X-ray examination revealed an increase in new bone volume in the experimental group 6 months postoperatively. pQCT showed that immature bone density was higher in the experimental group. Micro-CT images revealed well formed new bone along the original contour of the dome-shaped membrane in the experimental group. Histologically, inflammatory infiltration of tissue surrounding the membranes was slight. These results suggest that combining the poly(L-lactide-co-epsilon-caprolactone)/beta-tricalcium phosphate membrane and bFGF-gelatin sponge is promising for alveolar ridge reconstruction.

Factors affecting mandibular residual ridge resorption in edentulous patients: a preliminary report.

The aim of the study was to assess the rate of mandibular residual ridge resorption in edentulous patients and to analyse the factors which determine this process. A group of 35 edentulous patients aged between 51 and 89 years, with a mean age of 74 (65-78) years, were included in the study. Individual factors (age, gender and duration of edentulousness), local biochemical parameters (oral hygiene and history of periodontal diseases) and systemic biochemical parameters (calcium and phosphate metabolism, diet, smoking, alcohol intake and systemic diseases), as well as physical factors involved in the process (the use of prosthetic dentures), were analysed. The study was performed on the basis of the results of dental examinations, assessment of panoramic radiograms, research surveys and total calcium and phosphate serum levels, which were determined using a calorimetric method. Bone resorption in the mandible affected all the study patients to varying extents. More than half the edentulous patients showed a high degree of mandibular residual ridge resorption. The duration of mandibular edentulism was found to be closely associated with values of the radiological IC/IM index, which is generally considered to reflect the degree of mandibular resorption. Total calcium serum levels were shown to correlate positively with the value of IC/IM index in these patients.

A study to assess the relative influence of age and edentulousness upon mandibular bone mineral density in female subjects.

OBJECTIVE: The aim of this study was to assess the relative influence of age and edentulousness upon mandibular bone mineral density (BMD) in a sample of dentate and edentulous female subjects. STUDY DESIGN: Seventy-two patients (43-79 years of age; mean age, 62.5 years), of whom 49 were edentulous and 23 dentate, underwent dual x-ray energy absorptiometry (DXA) to determine the BMD of the body of mandible. Mandibular BMD was measured using DXA. The investigators independently determined rectangular regions of interest (ROIs) on the mandibular images, and the computer calculated the BMD of these specified regions. For the dentate patients, the ROIs were placed to exclude the roots of teeth. RESULTS: A linear multiple regression model was fitted to the dependent variable, mandibular body BMD, with age and whether the patient was edentulous or dentate being explanatory factors in the statistical model. The variable describing the dentate/edentulous state was not significant in the statistical model (P = .91). The model showed that age was significantly related negatively to the BMD of the mandibular body (P = .01). CONCLUSION: Age was a predictor of mandibular BMD but edentulousness was not.

Masticatory performance in postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses.

PURPOSE: Oral cancer develops frequently in older populations. In Japan, the incidence of oral and pharyngeal cancer is 9,201 per year, with such tumors accounting for 1.74% of all cancers. Although obturator prostheses play an important role in the rehabilitation of postmaxillectomy patients, clinicians sometimes experience difficulty in placing obturator prostheses in edentulous maxillae, and criteria for the objective evaluation of treatment outcome have yet to be established. The present study aimed to investigate postsurgical factors influencing the masticatory performance of postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses. MATERIALS AND METHODS: The extent of the hard palate defect, status of the mandibular dentition, mouth-opening distance, and maximum occlusal force were investigated, and masticatory performance was measured using a testing gummy jelly in 27 postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses. The influence of these items was evaluated quantitatively, and theoretical masticatory performance for each subject was calculated using multiple-regression analysis (quantification method type 1). RESULTS: Although average masticatory performance was almost equivalent to that of healthy, independent older patients with occlusal support classified as Eichner C, considerable individual variation was noted among subjects. The order of strength of influence on masticatory performance was identified by category weight: extent of hard palate defect > status of posterior mandibular teeth > maximum occlusal force > mouth-opening distance. A relatively high correlation (R2 = 0.78, P < .01, Pearson correlation coefficient) was evident between theoretical and actual values. CONCLUSION: Masticatory performance could be predicted by evaluating postsurgical factors in patients with edentulous maxillae fitted with obturator prostheses.

Biomechanics of the mandible part I: measurement of mandibular functional deformation using custom-fabricated displacement transducers.

PURPOSE: The purpose of this study was to measure corporal approximation, dorsoventral shear, and corporal rotation in edentulous subjects treated with dental implants, during normal mandibular movements. MATERIALS AND METHODS: Three patterns of jaw deformation (corporal approximation [CA], corporal rotation [CR], and dorsoventral [DV] shear) were measured using custom-fabricated displacement transducers in 12 edentulous subjects who had been treated with dental implants. Measurements were made in real time using a multichannel analogue/digital converter and a personal computer for data storage and analysis. Corporal approximation was measured as the linear change in the orientation of the 2 implants in the horizontal plane. Corporal rotation was recorded as a relative rotation of the right and left mandibular bodies projected into the frontal plane, and dorsoventral shear as the relative rotation of the 2 implants projected onto the median sagittal plane. RESULTS: All 3 patterns of mandibular deformation occurred concurrently and immediately on commencement of jaw movement. Different jaw movements produced different patterns of mandibular deformation. The highest values of jaw deformation were recorded during protrusion. CA ranged between 11.0 microm and 57.8 microm. Corporal rotation and DV shear ranged between 0.4 degrees and 2.8 degrees . CONCLUSION: This clinical study shows and measures 3 different and concurrent patterns of jaw deformation, during normal mandibular movements, using custom fabricated displacement transducers. The transducers may have a potential for routine clinical applications.

[Quantitative and qualitative comparison of the maxillary bone regeneration after beta-tricalcium phosphate and autogenous bone implantation]. / A maxilla csontregenerációjának mennyiségi es minoségi osszehasonlítása beta-tricalcium phosphate es autolog csontbeültetés után.

Graft insertion can effectively enhance the regeneration of debilitated bone. The effects of an alloplastic bone-replacing material, beta-tricalcium phosphate (Cerasorb), and of autogenous bone graft were compared. In 17 edentulous patients, the maxillary sinus floor was extremely atrophied to such an extent that implant placement was impossible. The Schneiderian membrane was surgically elevated bilaterally by insertion of Cerasorb (experimental side) and autogenous bone graft (control side). After surgery, the recovery was followed clinically and radiologically. After 6 months, 68 bone cylinders were excised from the grafted areas and implants were inserted into their places. The bone samples were embedded into resin, and the osteointegration of the grafts was studied histologically. Trabecular bone volume (TBV) and trabecular bone pattern factor (TBPf) were quantified by histomorphometry. Cerasorb proved to be an effective bone-replacing material with osteoconductivity; it was capable of gradual disintegration, thereby providing space for the regenerating bone. The new bone density was not significantly different on the experimental and control sides (32.4 +/- 10.9% and 34.7 +/- 11.9%, respectively). However, the graft biodegradation was significantly slower on the experimental side than on the control side. The TBPf value was lower on the control side than on the experimental side (-0.53 +/- 1.7 mm(-1) and -0.11 +/- 1.4 mm(-1), respectively); but this difference was not significant. Six months after insertion of the grafts, the bone of the augmented sinus floor was strong and suitable for anchorage of dental implants, irrespective of whether autogenous bone or Cerasorb particles had been applied.

A biomechanical comparison of 2 techniques for reconstructing atrophic edentulous mandible fractures.

OBJECTIVES: The purpose of this investigation was to evaluate and compare the biomechanical behavior of 2 techniques for the reconstruction of atrophic edentulous mandible fractures. MATERIALS AND METHODS: Thirty polyurethane atrophic edentulous mandible replicas (Sawbones, Vashon Island, WA) were used in this investigation (10 controls, 10 replicas of 2 different fixation techniques). The first reconstruction technique was a traditional titanium locking reconstruction plate affixed to the lateral border (buccal surface) of the mandible. The second reconstruction technique used the same type of plate, but placed it on the inferior border of the mandible. Both constructs were subjected to vertical loading at the symphysis and torsional loading at the body regions of the mandible replicas by an Instron 1331 (Instron, Canton, MA) servohydraulic mechanical testing unit. Mechanical deformation data within a 0-900 N range were recorded. Maximum load, displacement at maximum load, and stiffness were determined. Means and standard deviations were derived and compared for statistical significance using a Fisher's Protected Least Significant Differences Test with a confidence level of 95% (P < .05). Second- and third-order polynomial best-fit curves were also created for each group to further evaluate the mechanical behavior. RESULTS: For symphysis loading, statistically significant differences were noted between the control group and both of the plating techniques for displacement at maximum load. However, no differences were noted between the experimental groups for displacement at maximum load, stiffness, or maximum load. For body loading, statistically significant differences were noted between the control group and the inferior border plating group for displacement at maximum load. However, no differences were noted between the experimental groups for displacement at maximum load, stiffness, or maximum load. CONCLUSION: During this bench top investigation, there were no significant differences noted in mechanical behavior between the 2 specific experimental groups for any of the conditions measured. When placed in the context of functional parameters, both of the plating techniques met or exceeded the requirements for loading.