Symphyseal Region Research Articles

Three-dimensional evaluation of the mandibular symphyseal region in block graft harvesting for dental implants using cone-beam computed tomography.

PurposeThe purpose of this study was to analyze the quantity and quality of the mandibular anterior alveolar bone in terms of alveolar width, density, and total alveolar height (TAH) based on dental status, gender, and age. Additionally, this study aimed to quantitatively evaluate the available alveolar height for graft harvesting (AHGH) and examine its variability based on the aforementioned factors.Materials and MethodsThis retrospective cone-beam computed tomographic study included a total of 100 subjects. On the basis of gender, dental status, and age, the scans were divided into 3 primary groups and 8 subgroups. The mandibular alveolar width and density were measured 5 mm mesial to the mental foramen bilaterally and at the midline. The TAH was measured at the midline, and the AHGH was measured as the midline distance between 5 mm apical to the root of the canines and 5 mm superior to the lower border.ResultsThe mandibular alveolar width was statistically similar between dentulous and edentulous patients (P>0.05). A significantly greater density was observed at the midline in edentulous patients (P<0.05). The TAH was significantly greater in edentulous male patients than in edentulous female patients (P<0.05). Dentulous and male patients had significantly greater AHGH than edentulous and female patients, respectively (P<0.05).ConclusionBased on the data evaluated in this study, it can be concluded that the mandibular symphyseal area has adequate bone quality and quantity for bone graft harvesting for dental implant therapy.

SURGICAL TREATMENT ASSOCIATED WITH LIQUID NITROGEN CRYOTHERAPY IN ODONTOGENIC MYXOMA IN THE MANDIBLE: A CASE REPORT

The odontogenic myxoma is a benign odontogenic tumor, with aggressive characteristics, capable of causing many sequelae with a consequent decrease in a patient's quality of life. The present study aims to report a clinical case of odontogenic myxoma treated by radical surgery in association with liquid nitrogen cryotherapy. A 37-year-old female patient sought dental care with complaints of increased jaw volume but was otherwise asymptomatic. Clinical examination revealed increasing in volume in the vestibular-lingual region of the mandibular symphysis. Radiographically, an extensive multilocular radiolucent area was observed. The proposed treatment was the surgical approach of marginal block resection, with preservation of the mandibular base for bow maintenance, associated with the freezing of the region in order to minimize the risks of recurrence, due to the lack of capsule and lesion's loose consistency. The patient is under a 1-year nonsymptomatic follow-up, without recurrence and rehabilitation with a partial, removable denture.

Scelidosaurus harrisonii from the Early Jurassic of Dorset, England: cranial anatomy

AbstractScelidosaurus harrisonii is an early (Late Sinemurian) armoured ornithischian dinosaur whose remains have, to date, only been recovered from a restricted location on the south coast of Dorset (Charmouth), England. This dinosaur has been known since 1859, but only on the basis of a partial description found in two articles published in the early 1860s by Richard Owen. The original material, discovered in 1858, comprised the majority of the skull and its associated postcranial skeleton, and represents the first ever, more or less complete dinosaur discovered. In addition to the original material, a number of further discoveries have been made at Charmouth; these latter supplement the information that can be gleaned from the original specimen. This article describes the skull of Scelidosaurus.The external surface of individual skull bones in ontogenetically relatively mature individuals displays exostoses, a patina of fibrous or granular-textured bone that anchored an external shielding of keratinous scales. There is a small, edentulous rostral beak, behind which is found a row of five heterodont premaxillary teeth. There is a minimum of 22 maxillary teeth and 27 dentary teeth in jaws of the largest well-preserved individuals known to date. Both dentitions (upper and lower) are bowed medially and are sinuous longitudinally. Maxillary and dentary crowns are tilted lingually on their roots, trapezoidal in outline and have crenellate (coarsely denticulate) margins. Adjacent crowns of teeth have mesiodistally (anteroposteriorly) expanded bases that overlap slightly and are consequently arranged en echelon. The dentitions are flanked by deep cheek pouches. Tooth abrasion is usually discontinuous along the dentition. In one individual nearly all teeth seem to be fully emerged and there is little evidence of abrasion. There is no physical evidence of a predentary, but the presence of this (typically ornithischian) element may be inferred from the structure of the symphyseal region of the dentary. The external narial and antorbital fenestrae are comparatively small, whereas the orbit and temporal fenestrae are large and open. A sclerotic ring was undoubtedly present and supported the eyeball, but it is too poorly preserved to allow it to be reconstructed with accuracy. A prominent supraorbital brow ridge overhangs the orbit. There are three osteoderms: palpebral, middle supraorbital and posterior supraorbital, sutured to the dorsal margin of the orbit. The occiput provides an area for attachment of a pair of curved, keratin-sheathed, osteodermal horns.Epistyloid bones project from the ventrolateral region of the braincase; their distal ends flank the anterolateral region of the neck. Rugose facets on either side of the basioccipital are suggested to have provided attachment sites for the epistyloid bones. Internally, the skull has a deeply vaulted snout and the nasal chambers are roofed by what are here named epivomer bones that appear to have been sutured to the dorsolateral edges of the vomers. Unusually, among dinosaurs generally, an epipterygoid is preserved attached to the dorsolateral surface of the pterygoid; there is no obvious point of articulation for the epipterygoid against the lateral wall of the braincase. A deep pit on the posterior surface of the quadrate of an immature specimen is suggestive of the existence of a remnant of cranial pneumatism. This pit becomes occluded in larger, more mature specimens.

Bite Force, Masseter Thickness, and Oral Health-Related Quality of Life of Elderly People with a Single-Implant Mandibular Overdenture.

To compare maximum bite force, masseter thickness, and oral health-related quality of life (OHRQoL) in elderly patients rehabilitated with conventional complete dentures (CDs) and single-implant overdentures (SIOs). A paired design was conducted, and 12 elderly patients were selected. Initially, a set of new CDs was manufactured and placed. After a 2-month adaptation period, the mandibular CD was transformed into an SIO by inserting one osseointegrated implant into the symphysis region. All variables were evaluated 2 months after both treatments (CD and SIO). Maximum bite force was evaluated using pressure sensors, while masseter thickness was obtained via ultrasound during muscle contraction and relaxation. The Oral Health Impact Profile for edentulous people (OHIP-Edent) was used to measure OHRQoL. Data were analyzed using Student t test and Wilcoxon test. Pearson coefficient of correlation between bite force and masseter thickness was calculated. Values for maximum bite force and masseter thickness during contraction increased significantly after SIO use (P < .001), indicating an improvement in muscle function. Considering OHRQoL, the general score and the domains functional limitation and physical pain were reduced (P < .05), indicating better perception of OHRQoL, with SIO use. Moreover, masseter thickness during contraction was moderately correlated with bite force (r = 0.480; P = .018). Using SIO increased the maximum bite force and masseter thickness of elderly patients, leading to an improved OHRQoL.

Enhance Mandibular Symphyseal Surface Bone Growth with Autologous Mesenchymal Stem Cell Sheets: An Animal Study.

The size and shape of the chin strongly influence facial profile and harmony. The current correction of chin deficiency mostly relies on genioplasty surgery involving osteotomy. To avoid osteotomy, one possible alternative is to enhance bone growth at the mental protuberance area with cell sheet transplantation. This study was undertaken to evaluate the efficacy of this approach in a pig model. Five 4-month-old pigs were included for mandibular bone marrow aspiration and MSC isolation. Triple-layer MSC sheets were then fabricated and utilized using culture-expanded MSCs. Four weeks after bone marrow aspiration, subperiosteal pockets were created on the labial symphyseal surface, followed by transplantation of autogenous MSC sheets to one randomly chosen side with the other side (control) receiving no transplantation. Six weeks after the surgery, the pigs were euthanized and the specimens from both sides were collected for computed tomography (CT) and histological and immunohistochemical analysis. Measurements between the experimental and control sides were compared using paired t tests. MSC sheet fabrication and transplantation were reliably conducted. The labial cortical bone thickness increased significantly with MSC sheet transplantation by an average of 2mm (p = 0.0001). The average measurements of mineral apposition rate and cell proliferation at the cell sheet side tended to be higher than the control side although the differences did not reach statistical significance (p = 0.1-0.2). Tissue mineral density measurements from CT images and bone volume fraction (BV/TV) measurements from histologic images were identical between the two sides (p > 0.5). These data provide a proof of concept that autologous MSC sheets may be transplanted to the subperiosteal region of the mandibular symphysis to stimulate local surface bone growth. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

The Gravettian child mandible from El Castillo Cave (Puente Viesgo, Cantabria, Spain).

This article documents an incomplete child's mandible found in H. Obermaier's excavation campaign (in 1912) in El Castillo Cave, Spain. This fossil was assigned to what was then considered a phase of the "Aurignacian-delta". We exhaustively analyzed the original Obermaier documents, with particular attention to those corresponding to the year of the discovery. We extracted a bone sample to radiocarbon date the fossil directly. We also followed established methods to measure, describe and compare the mandible with other human remains. The analysis of Obermaier's documents and new data derived from modern excavations, show that the mandible was discovered in an interior area of the cave. Direct radiocarbon dating yielded a result of 24,720 ± 210 BP and 29,300 - 28,300 cal BP, a date similar to those known for the Gravettian technocomplex both in the El Castillo site and across Europe. The jaw corresponded to a child aged 4-5 years, with modern morphology, but with a certain robustness, especially in the symphyseal region. Comparisons were made with several modern children (Granada, Spitalfields, and Black series) and with immature fossils (European Aurignacian and Gravettian). The few differences between the modern and the fossil children are related to the symphysis and mandibular corpus thickness and height, and to the symphyseal morphology and larger teeth dimensions. Paleoisotopic data for Castillo C correspond with a varied diet. Numerous cutmarks were identified in the midline internal symphyseal region. The results agree with those published for other fossils of similar age and chronology (e.g., the mandible of the Lagar Velho child) and show clear differences from the jaws of the young Neanderthals. The interpretation of the original data on the mandible discovery may indicate the destruction of a burial and the displacement, by percolation or by a den, at least of part of the skeleton. The perimortem manipulations in the child's mandible are the first described in the Gravettian world of Western Europe.

A New Peirosaurid Crocodyliform from the Upper Cretaceous Lago Colhué Huapi Formation of Central Patagonia, Argentina

Peirosaurid crocodyliforms were diverse and abundant in the Cretaceous of the Gondwanan landmasses, especially South America. Here, we describe Colhuehuapisuchus lunai, gen. et sp. nov., a new peirosaurid taxon from the Upper Cretaceous (Campanian–?lower Maastrichtian) Lago Colhue Huapi Formation of southern Chubut Province in central Patagonia, Argentina. Although represented by only the anterior ∼one-third of the mandible with several complete, in situ teeth, the new taxon exhibits a combination of distinctive morphologies that does not occur in other peirosaurids, including several mandibular and dental autapomorphies. The symphyseal region of the Colhuehuapisuchus mandible is transversely wider than that of any other representative of Peirosauridae, and as such the new form may be most closely related to other broad-snouted peirosaurids such as Barrosasuchus neuquenianus, Gasparinisuchus peirosauroides, and Patagosuchus anielensis. The exceptional diversity of snout and tooth shapes among definitive and probable members of Peirosauridae suggests the existence of a variety of ecological and dietary preferences within the clade. Colhuehuapisuchus constitutes the southernmost peirosaurid occurrence worldwide and arguably the youngest record from Patagonia, thereby expanding the paleobiogeographic range of these distinctive mesoeucrocodylians to nearly the end of the Mesozoic and the southern tip of South America.

Effects of orthopedic skeletal Class III correction in growing subjects using skeletal anchorage and Class III elastics

Aim of the study: The objective of this study was to evaluate the skeletal and dental effects of intermaxillary Class III elastics using bone anchored miniplates compared to an untreated Class III control group.Subjects and methods: 24 subjects (14 females and 10 males) having skeletal Class III malocclusion with maxillary deficiency with an age range of 8-11 years old were divided into two groups 12 patients each (n=12). Group A constituted treatment with Class III elastics anchored to 4 titanium miniplates, 2 anchored in the zygomatic buttress of the maxilla and 2 miniplates anchored in the symphyseal region of the mandible at the lateral/canine region. Group B (n=12) constituted untreated skeletal Class III cases (control group). The treatment and observation periods for both groups were 8 months. Lateral cephalometric radiographs were taken for the patients at start of treatment (T1) and at the end of the treatment/observation periods (T2). The radiographs were analyzed by performing lateral cephalometric analysis. Independent student t test was done to compare variables between the two groups.Results: There was correction of the skeletal Class III in the miniplates group with statistically significant increase in angle SNA (mean 3.50° ± 0.68), A-Nperp (mean 4.04mm ± 1.20), ANB (mean 4.06◦±0.95) and Witts appraisal (mean 4.91mm ± 1.76) .Slight mandibular retrusion occurred with a reduction in angle SNB (mean -0.56◦ ±0.57). Changes in B-Nperp were (-1.85mm±1.36).Overjet correction was obtained and no significant changes in the maxillary incisor angulation was observed. There was proclination of mandibular incisors by (mean 6.43◦±2.11).Conclusions: The use of intermaxillary Class III elastics and miniplates in the orthopedic treatment of skeletal Class III is a successful technique with more skeletal than dental effects.

Stability of camouflage treatment using mandibular full arch distalization in Skeletal Class III malocclusion

Skeletal Class III malocclusion is a relatively common form of malocclusion in Korea. In borderline cases where only mild skeletal discrepancy exists and if worsening of the facial profile is expected as a result of premolar extraction, mandibular full arch distalization with miniscrews is the treatment of choice. The purpose of this study was to investigate the pattern of tooth movement and evaluate the stability of mandibular full arch distalization and to identify correlation between stability and factors such as initial skeletal pattern, dental changes during treatment and alveolar bone in symphysis region using lateral cephalograms.

Prospective evaluation of morbidity in patients who underwent autogenous bone-graft harvesting from the mandibular symphysis and retromolar regions.

Autogenous bone grafts are the most favorable and predictable types of bone graft due to their osteogenic, osteoinductive, and osteoconductive properties. The advantages of harvesting from mandibular bone are that it requires only local anesthesia, is less invasive, has less morbidity, and avoids harvesting from distant sites, thus making it the best choice for maxillary bone reconstruction. The aim of this study was to evaluate inferior alveolar nerve (IAN) neurosensory disturbances after autogenous bone graft harvesting from the mandibular symphysis and retromolar region to reconstruct maxillary sinus height for posterior dental implant placement and the effect of these disturbances on patient satisfaction. Fifty-four patients were invited to participate in this study. Autogenous bone graft was harvested from the mandibular symphysis and retromolar regions. After the procedure, the patients were evaluated by means of an adapted questionnaire to determine if they had complaints of neurosensory disturbances at the following time intervals: immediately, 1, 2-5, 6, 7-11, and 12 months postsurgery. Immediately after surgery, 28 patients described sensory changes and 25 reported paresthesia of inferior lip. Only three patients reported pain, and one patient experienced dental hypersensitivity after the surgical procedure. During the evaluation period, the patients reported a decrease in paresthesia and a return of sensation to areas innervated by the IAN. After 12 months, five patients still reported paresthesia of areas innervated by the IAN. Beside this, patients reported significant clinical improvement from the beginning of the evaluation, as 49 patients were satisfied with their treatment outcomes. Harvesting bone grafts from the mandibular symphysis results in greater postoperative morbidity upon immediate evaluation compared with bone graft harvesting from the retromolar region. Nevertheless, during clinical follow-up, the results of both treatments showed that sensation was eventually recovered, depending on the healing period.

Ellipsoid radiolucent lesion of the mandible

A 76-year-old man was referred for evaluation of a mandibular lesion incidentally discovered in a panoramic radiograph. His medical history was remarkable for hypertension, gout, degenerative disk disease, and bilateral total hip replacement. The patient denied any pain or numbness. However, he reported that his mandibular right canine had been moving distally over the past several years. Oral examination revealed mild cortical expansion of the right mandibular residual ridge. The mucosa covering the ridge appeared normal. On questioning, the patient gave a long history of multiple tooth extractions for caries. Examination of the head and neck did not reveal any palpable lymph nodes. The panoramic radiograph showed a well-circumscribed, corticated, ellipsoid, unilocular, radiolucent lesion occupying the right mandibular body and symphysis region (Figure 1). A cone-beam computed tomographic examination showed the lesion extending from the left mandibular central incisor anteriorly to the edentulous area of the right mandibular second molar posteriorly. The lesion had caused some erosion and expansion of the buccal and lingual cortices (Figure 2). It also had caused distal tipping of the canine tooth and inferior displacement of the mandibular canal. The overall estimated dimensions were 17 millimeters (height) ✕ 14 mm (width) ✕ 47 mm (length). The patient subsequently underwent further investigation; after aspiration of a serosanguinous fluid from the lesion, an incisional biopsy was obtained (Figure 3). Figure 2Axial cone-beam computed tomographic scan shows thinning and expansion of the buccal and lingual cortices. View Large Image Figure Viewer Download Hi-res image Figure 3Microscopic examination of a cystic structure with lining epithelium and a fibrous connective tissue wall. The lining epithelium is composed of variably thickened, nonkeratinizing stratified squamous epithelium. Scattered inflammatory cells, hemosiderin deposits, and extravasated red blood cells are present in the fibrous wall (hematoxylin and eosin, ×40 magnification). View Large Image Figure Viewer Download Hi-res image Dr. Omami is an assistant professor, Department of Oral Health Practice, College of Dentistry, University of Kentucky, 800 Rose St., Lexington, KY 40536.

Human Mandible Prenatal Morphogenesis

Introduction This study was performed with the aim of detecting the interaction between cartilaginous and bone tissues in the process of mandible morphogenesis in human embryos. Material and Methods Whole-mount skeletal preparations, stained with Alcian blue and Alizarin red, as well as serial histological sections impregnated with silver and stained with hematoxylin and eosin were studied. A total of 48 human embryos/fetuses from 5 to 29 weeks of age were used. Results In the mandible anlage, in addition to the woven bone, cartilaginous and chondroid tissues are present. Cartilaginous tissue islets are localized at the tip of the condylar and coronoid processes and also in the region of the mandibular symphysis. The chondroid tissue is incorporated into the bone in the region of the mandibular symphysis, along the edge of the coronoid process, and also in the alveolar part of the mandible. Conclusion Meckel’s cartilage participates in the formation of the mandibular body, and its remains persist in the area of the mandibular symphysis until the second half of the prenatal development.

Masticatory function and bite force of mandibular single-implant overdentures and complete dentures: a randomized crossover control study

PurposeThe study aimed to compare the mixing ability (MA), comminuting ability (CA), and maximum bite force (MBF) of single-implant overdentures (IODs) and clinically acceptable complete dentures (CDs) through a randomized crossover control trial. MethodsNew CDs were fabricated for 22 patients. One implant was inserted in the middle of the symphyseal region for each patient. The patients were randomly allocated into two groups: group IC received an IOD, whereas group CI received a CD, for 2 months; the treatments were interchanged for the next 2 months. The MA, CA, and MBF were evaluated with the old CDs, new CDs (at the end of CD treatment period), and IODs (at the end of IOD treatment period). ResultsThe MA, CA, and MBF of the IODs were significantly higher than those of the old and new CDs (p < 0.01). New CDs only showed a significant improvement in MA (p < 0.05), while there were no significant differences in CA and MBF between the old and new CDs. ConclusionsCompared with the CD, IOD is more effective in restoring the MA, CA, and MBF of edentulous mandibles.

Median Perforating Canal in Human Mandible.

Surgical interventions in the anterior region of the human mandible are associated with many complications. Some anatomical structures like the median perforating canal were discovered in mammals. Such canals may be a cause of concern that needs attention in human mandible. The purpose of the present study was to evaluate the occurrence, location, and course of median perforating canal and its associated extensions in the anterior segment of the human mandible in cone beam computed tomography scans (CBCT). Data were collected from 160 CBCT scans, and evaluated. The incidence was 23.75% for median perforating canal with wide anatomical variations concerning the related lingual and labial extensions. Median perforating canal and their associated lingual and labial foramina are frequently seen in human mandible. A thorough investigation of the symphyseal region using CBCT must be taken into account when targeting surgical intervention in this area.

The morphology of the human mandible: A computational modelling study.

Cephalometric methods have been used to evaluate morphometric measurements of the mandible and quantify sex-related anatomical features; however, most studies to date employ a limited set of location-specific measurements without considering the entire three-dimensional anatomy of the mandible. The aims of this study were to develop statistical shape models (SSMs) of partially edentulous male and female mandibles to evaluate inter-subject morphological variability and secondly to assess the effectiveness of discrete clinical morphometric measurements in prediction of complete three-dimensional mandible geometry. Computed tomography images of forty partially edentulous female and twenty-five male subjects were obtained, and SSM developed using mesh fitting, rigid body registration and principal component analysis. Analysis of female and male SSMs showed that the variation along their first principal components was size-related. Sex-differentiating pure shape variations were found along the first principal component of size-normalised SSM and were observed to be most prominent in the symphysis and posterior ramus regions of the mandible. Seven morphometric measurements were found to characterise female and male shape prediction optimally. The capability to rapidly generate accurate patient-specific shape-predictive models of the mandible may be useful for implant development and pre-operative planning, particularly in the absence of bony structures following trauma or tumour resection.

Mandibular incisive canal and lingual foramina characterization by cone-beam computed tomography

Many patients have haemorrhagic and neurologic complications after surgery at the symphysis region, while this area between the mental foramina is commonly considered to be risk-free because the presence of vasculo-nervous anastomoses found in the mandibular incisive canal (MIC) and lingual foramina (LF). The purpose of our study was to better analyse these anatomical structures to better identify and preserve them during surgery. This prospective radio-anatomical study evaluated the presence, morphology and topography of MIC and median LF (MLF) and paramedian LF (PLF) by cone-beam computed tomography according to age, gender and dentition of 50 consecutive patients. Among the MIC, 99% were visualized at their origin. Their visibility decreased gradually towards the symphysis. The MIC had a larger diameter and followed a significantly more superficial and more vestibular way in older patients. At least, one MLF by hemimandible was found whereas PLF were found only in 68% of the cases. The mean distance from the basal border was 7.11mm for the lower MLF, 16.33mm for the upper MLF and varied from 11.15 to 10.85mm for the left and right PLF. Our study suggests that MIC and LF are constant structures with anatomical variations and that three-dimensional topographic study of the interforaminal region would be beneficial in patients requiring surgery in this area to reduce the risk of haemorrhage and neurologic complications.

Changes in masticatory performance of edentulous patients treated with single-implant mandibular overdentures and conventional complete dentures.

The aim of this study was to test the effect of a single-implant mandibular overdenture (SIMO), compared with conventional complete denture (CD), on masticatory performance measured by the mixing ability of a two-coloured chewing gum. A sample of edentulous subjects was randomly assigned to the SIMO (n=15) and CD (n=19) groups. Patients in both groups received a set of new complete dentures, and the SIMO group received a single implant in the symphyseal region of the mandible (Straumann® Standard Plus SLActive®) and an eliptical matrix and ball attachment for denture retention. Masticatory tests were performed using a two-colour chewing gum (Vivident Fruitswing, Perfetti van Melle, Turkey) for 20 and 50 chewing cycles. Colour-mixing ability was assessed by electronic colourimetric analysis (ViewGum©, Dhal Software, Greece), expressed by the variance of hue. Tests were performed at baseline and at the 6- and 12-month follow-ups. Multilevel linear regression was used to model the changes in masticatory performance. Groups were similar at baseline for 20 and 50 cycles (P>0.05). A significant linear effect was observed on time points for 20 and 50 cycles (P<0.001). No difference was observed between treatment groups factor (P>0.05). However, the way masticatory performance varied according to time points differed in the CD and SIMO groups for 20 cycles (P=0.048). Masticatory performance improved significantly after 12months, irrespective to the insertion of a single implant to retain a mandibular overdenture. Moreover, results suggest that SIMO treatment may perform better than CD in the shorter follow-up period.

Psychometric Analysis and Masticatory Efficiency of Elderly People with Single-Implant Overdentures.

The aim of this paired clinical study was to evaluate psychometric parameters (patient satisfaction and masticatory ability) and masticatory efficiency in elderly people before and after oral rehabilitation by a single-implant overdenture. This study included elderly individuals with residual alveolar bone height classified as Class III or IV according to the American College of Prosthodontics, and who wore clinically unsatisfactory complete dentures. Subjects first received new maxillary and mandibular conventional complete dentures. After 2 months of patient adaptation to the new complete dentures, subjective and objective variables were measured. Satisfaction with the new complete dentures was verified by applying a visual analog scale to rate patient satisfaction with stability, comfort, ability to chew, ability to speak, ease of cleaning, esthetics, and general satisfaction of their new complete dentures. Masticatory ability was assessed by asking participants to rate on a visual analog scale their ability to chew foods with different roughness and consistencies. Masticatory efficiency was measured by the sieving method using a silicone-based artificial test food. After evaluations were completed, each participant received one implant, which was placed in the symphysis region. After 3 months of implant osseointegration, the conventional complete dentures were transitioned to mandibular single-implant overdentures through placement of a low-profile attachment on the intaglio surface of the prostheses. Subjects used the single-implant overdentures for 2 months, and then all variables were reevaluated. Parametric t test and nonparametric Wilcoxon statistical tests were used to analyze data. Participants reported increased satisfaction with stability of their mandibular single-implant overdentures compared with their new conventional complete dentures. However, satisfaction with the esthetics decreased when the new complete denture was converted into the single-implant overdenture (P < .05). Masticatory ability with the rehabilitation was not different between the new conventional complete dentures and the single-implant overdentures; however, transition to the single-implant overdenture greatly increased masticatory efficiency (P < .0001). Single-implant overdentures changed the patient perceptions, improving their satisfaction with stability, although decreasing satisfaction with esthetics. Despite that, masticatory efficiency of elderly individuals with decreased residual bone height was greatly improved after single-implant overdenture use.

Comparative evaluation of a single 2.0-mm AO locking reconstruction plate with conventional miniplate osteosynthesis for treatment of linear non-comminuted fractures of symphysis and parasymphsis region of the mandible

The objective of the study was to evaluate and compare the relative efficacy of treating linear non-comminuted mandibular fracture of symphysis and parasymphysis region using single 2.0-mm AO locking reconstruction plate or using two conventional miniplates. In this study, 80 patients of symphysis or parasymphysis fracture were divided randomly in two equal groups and treated with open reduction and internal fixation using two 2.5-mm miniplates or with a single 2.0-mm AO locking reconstruction plate. Operating time in case of open reduction and fixation using a single 2.0-mm locking reconstruction plate was significantly less when compared to open reduction and fixation using two conventional miniplates. Both groups showed satisfactory fracture reduction and healing. No postoperative malocclusion was noted, and both groups showed comparable improvement in masticatory efficiency. In conclusion, fracture fixation using a single 2.0-mm AO locking reconstruction plate without use of a second plate at the superior border for treatment of linear non comminuted mandibular fracture in symphysis and parasymphysis region gives comparable results as with treatment by conventional miniplate system and provides significant savings in operating time, ease of use and decrease in amount of hardware incorporated in the body.

Biomechanical Evaluation of the Sheep Mandible as a Model for Studying Fixation Methods

Recently, there has been increased interest in the use of natural jaws for better results in bone fixation studies. Thus, the sheep mandible has been chosen for such studies. The aim of this study was to evaluate the length and resistance of the sheep mandible when submitted to a compression test with freedom in the three axes of space. Seventy fresh sheep (Ovis aries) mandibles were used in this study. Initially, the soft tissues were removed, and measurements of the mandible size were performed. Fifty mandibles were selected for mechanical testing based on the mean values from this assessment. The mandibles were joined by fixation in the symphyseal region and were tridimensionally deformed. A metallic support suitable for study of the mandible under efforts with freedom in the three axes in space was used. For this test, three displacement cycles were applied. Based on the mean stiffness, 35 mandibles were selected. The mean value of the sheep mandible mensuration was 13.6 cm ± 0.53 cm. The mean value of the sheep mandible stiffness was 153.5N ± 54.0 N. These data are useful for future studies on fixation systems for fractures and orthognathic surgery.