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PubMed1995

Prosthetic management of the atrophic mandible using endosseous implants and overdentures: a six year review.

This paper presents the treatment results and experiences gained from a retrospective study of patients treated with the IMZ osseo-integrated implant system and mandibular overdentures. Patients experiencing problems wearing conventional dentures were assessed by the implant team and 65 cases were treated with 154 endosseous implants placed in the edentulous mandible. Two to four implants were placed in each case and in addition some patients have had augmentation of the mandible with hydroxyapatite. The definitive mandibular prostheses were supported by both implants and the residual ridges. A variety of retention systems were utilised, which included different types of bar and clip, stud attachments, and magnets. The patients have been followed up regularly and evaluated after periods of between one and six years. Six implants have failed over this time resulting in a success rate of over 96%. Most patients expressed a high degree of satisfaction with their new overdentures. There was, however, a considerable burden of maintenance care required for the patient group examined. The findings demonstrate that implant retained overdentures offer a highly effective means of oral rehabilitation for the atrophic mandible, restoring both oral function and facial form.

Adult↗
PubMed2006

Treatment planning of the edentulous mandible.

Edentulism can be a debilitating handicap. Zarb described endentulous individuals who could not function as 'denture cripples'.(1) Most difficulty with complete denture prostheses arises from the inability to function with the mandibular prostheses. Factors that adversely affect successful use of a complete denture on the mandible include: 1) the mobility of the floor of the mouth, 2) thin mucosa lining the alveolar ridge, 3) reduced support area and 4) the motion of the mandible (Figs 1,2). These factors alone can explain the difficulty of wearing a denture on the mandibular arch compared to the maxillary arch. The maxilla exhibits much less mobility on the borders of the denture than the mandible, moreover having a stable palate with thick fibrous tissues available to support the prostheses and resist occlusal forces. These differences explain most of the reasons why patients experience difficulty with using a complete denture on the mandibular arch compared to the maxillary arch.

Dental Prosthesis, Implant-Supported↗
PubMed1997

Trabecular bone pattern of the mandible. Comparison of panoramic radiography with computed tomography.

OBJECTIVES: To analyse the possible correlation between the trabecular bone pattern of the edentulous mandible visualized by panoramic radiography and the bone mineral density (BMD) measured by computed tomography (CT). METHODS: Panoramic radiography and CT were performed on 28 patients with edentulous mandibles. The trabecular bone pattern of 47 regions on the panoramic radiographs was classified into one of five grades. BMD was measured within circular regions of interest on the axial CT images in the corresponding trabecular area. The gradings were correlated with the CT values using one-way analysis of variance. RESULTS: There was a significant correlation between the grade of the trabecular bone pattern and the BMD (P < 0.0001). CONCLUSION: The proposed classification for the trabecular bone pattern on panoramic radiographs might be a useful aid for the evaluation of the edentulous mandible prior to implant placement.

Adult↗
PubMed1997

Trabecular bone volume and bone mineral density in the mandible.

OBJECTIVES: To explore the possible correlation between trabecular bone volume and bone mineral density in the mandible. METHODS: Bone mineral density of the trabecular bone was obtained by quantitative computed tomography of 22 edentulous anterior and posterior sections of nine mandibles obtained at autopsy. A computer-based image analysis system was used for morphometric measurements to derive trabecular bone volume from contact radiographs. RESULTS: A significant correlation was found between trabecular bone volume and bone mineral density. The trabecular bone volume varied significantly between and within mandibles. CONCLUSION: The high correlation between trabecular bone volume and bone mineral density means that the use of quantitative computed tomography prior to implant treatment is a valid procedure.

Aged↗
PubMed2000

Basic study of the measurement of bone mineral content of cortical and cancellous bone of the mandible by computed tomography.

OBJECTIVES: To develop an algorithm for automatic separation of cortical from cancellous bone in the mandible and for measuring mandibular bone mineral content (BMC). METHODS: A dried mandible was scanned together with a reference phantom by spiral CT. A new algorithm was developed specifically for the mandible and cross-sectional images reconstructed in the buccolingual plane. The cortical bone was extracted with a threshold of 80% of the peak height in the line-scan profile and the cancellous bone extracted separately. The volume and BMC were estimated. Images of cortical and cancellous bone were displayed in a plane approximating the orientation used for dental radiography and BMC expressed as aluminium-equivalents (Al-eqs). RESULTS: The ratio of cortical to cancellous bone by volume was 22:78, and the ratio of the BMC 60:40. Comparison of BMC from reconstructed CT with Al-eqs showed good correlation but was 1.5 times higher with CT. CONCLUSIONS: It is possible to separate cancellous from cortical bone automatically from CT images and to measure the BMC.

Absorptiometry, Photon↗
PubMed1985

Pubertal spurts in cranial base and mandible. Comparisons within individuals.

Serial data from cephalometric radiographs were analyzed for 34 boys and 33 girls who had cephalometric radiographs annually near each birthday from at least age 7 through 18 years. Spurts were defined for this study as increases between successive cranial base increments that exceeded 0.75mm/year in boys or 0.5mm/year in girls. The corresponding criterion for the mandible was 1.0mm/year in either sex. Pubescence was defined as the 4- year period spanning 2 years before and after peak height velocity. Spurts during pubescence were common, tending to occur about 1.6yr earlier in girls than boys. The mean increments at first pubertal spurt (FPS) and the mean sizes of FPS were about 25% to 33% greater in the boys than in the girls. The rate of growth during the year before FPS tended to be greater in the girls, while in the year after FPS it tended to be greater in the boys. The timing of FPS in either cranial base of mandible was not closely related to the onset of ossification in the ulnar sesamoid, the age at peak height velocity, or age at menarche. FPS generally occurred after the onset of ossification of the ulnar sesamoid, but before peak height velocity and menarche. There was no evidence of difference between craniofacial EPS in children who passed rapidly or slowly through pubescence, nor was any difference noted between the size of pubertal spurts in tall or short boys. larger total increments after peak height velocity were found in the short boys. Significant correlations were identified between the cranial base and the mandible in the timing but not in the magnitude of FPS. The children were approximately equally divided between those in whom cranial base spurts occurred first, those in whom mandibular spurts were first, and those in whom FPS occurred in both areas within the same annual interval.

Adolescent↗
PubMed2002

Effects of dietary consistency on the mandible of rats at the growth stage: computed X-ray densitometric and cephalometric analysis.

Thirty 3-week-old male Wistar rats were grouped into a hard diet control group, a kneaded-diet group, and a powdered-diet group. After 6 weeks of growth, all rats were killed under deep anesthesia. The effects of dietary physical consistency on the mandible were investigated with respect to morphology and bone mineral content using lateral cephalometric analysis and computed X-ray densitometry. Significant differences between the experimental and control groups were determined by measuring the means and standard deviation of the coordinates and differences between 15 points selected on the mandibles. Gonion (Go), which is a measurement of depth to the X-axis, was significantly less in the powdered-diet group, while the kneaded-diet group showed no significant differences. The most posterior point of the coronoid process (Cr) and the most posterior point of condylar process (Cd), which are measures of height to the Y-axis, were less in the kneaded-diet group than in the control group. In the powdered-diet group, Cr, Cd, Go and Infradentale were significantly less than in the control group. On the other hand, the bone mineral content was significantly lower in the coronoid process and angle of mandible in only the powdered-diet group.

Absorptiometry, Photon↗
PubMed1988

Mandible and hyoid bone movements during speech.

Relatively little is known about the extent to which speech-related movements of the mandible and hyoid bone involve rotation and translation. Data were derived from an existing high-speed cineradiograph of 27 disyllables produced by a single adult male speaker of English to address this issue. Time histories of relative locations of both bony components of the mandibular system, expressed in terms equivalent to the sagittal-plane coordinates of two landmarks on each, were analyzed to determine (a) their respective ranges of position and orientation, (b) associations between selected segmental and suprasegmental variables, and subregions of those ranges, and (c) interdependencies between articulator rotation and landmark displacement. In general, data from this speaker, for the mandible and hyoid bone, are consistent with previous reports for the mandible alone, all of which suggest that rotational and translational components of their motions are sufficiently independent to warrant kinematic descriptions that treat both structures as rigid bodies moving in a plane.

Cineradiography↗
PubMed1999

Effect of masticatory function on the internal bone structure in the mandible of the growing rat.

The influence of changes in the masticatory function on bone mass, bone density and cortical thickness was analyzed in different functional units of the mandible of the growing rat. Young male albino rats were fed either a hard diet or a soft diet for 4 wk. Undecalcified coronal sections were selected from five mandibular regions and microradiographic images of the specimens alongside an aluminium stepwedge were obtained. Bone mass and density were measured at selected sites with a computer-aided image analysis system. Cortical thickness was measured on diagrams. The reduced masticatory function in the soft diet group produced different adaptive responses in the tested regions of the mandible. Some regions showed reduced cortical thickness (underneath the incisor and lateral to the first molar and some locations of the ramus), a few showed reduced bone density (medial to the first molar and in the ramus), and only one showed both (in the ramus). Reduced bone mass was associated mostly with thinner cortical bone rather than lower cortical bone density. Changes in cortical thickness and changes in bone density may be two different mechanisms for adjusting local mechanical properties in the mandible of the rat. Masticatory muscle function is a determinant for the amount and density of cortical and trabecular bone and may possibly influence results of orthodontic tooth movement and its possible relapse.

Absorptiometry, Photon↗
PubMed1996

Loading conditions of endosseous implants in an edentulous human mandible: a three-dimensional, finite-element study.

The design of dental superstructures influences the loading on dental implants and the deformation of the anterior interforaminal bone in an edentulous mandible. This deformation causes stress in the bone around the implants and may lead to bone resorption and loss of the implant. The stress distribution around dental implants in an edentulous mandible was calculated by means of a three-dimensional, finite-element model of the anterior part of the jaw. This model was built from data obtained from slices of a single human mandible and was provided with four endosseous implants in the interforaminal region. The implants were either connected with a bar or remained solitary. The solitary implants or the bars were loaded either uniformly or non-uniformly. In case of a non-uniform distribution, either the central bar or the central implants were loaded or the lateral bars or the lateral implants were loaded. The most extreme stresses in the bone were always located around the neck of the implant. In the case of the uniform distribution of the loading there were more or less equal extreme principal stresses around the central and lateral implants. If the load was not uniformly distributed on the superstructure then the implant that was nearest to the place of loading showed the highest stress concentration; with connected implants there was a reduction in the magnitude of the extreme principal stresses compared to solitary implants.

Bite Force↗
PubMed2005

[Distraction osteogenesis in orthodontic surgery of the mandible].

Distraction osteogenesis is a bone creating procedure that can contribute materially to the treatment of Class II dento-skeletal disorders where the mandible is under-sized. Still, the serious commitments this treatment demands and the unpredictability of its occlusal results oblige practitioners to pinpoint precisely the indications for its use. We now believe that distraction osteogenesis can beneficially be employed for: 1--Adults with Class II malocclusions, a small mandible, and a lack of harmony between tooth and jaw size. This bone growing technique makes it possible to treat these patients without the extraction of premolars that would have been necessary in the traditional preparation for orthognathic surgery. 2--Patients whose mandibles are diminished in size in the area of the symphasis. Distraction osteogenesis of this anterior segment is the only way they can be treated without reduction of tooth structure or excessive labial tipping of teeth. 3--Some patients with short, or moderately short rami. We do not, at this time, believe that distraction osteogenesis is indicated for the treatment of any other kind of dento-facial deformity. But, in the future, improvement of surgical techniques and the miniaturization of appliances will doubtless extend its scope.

Adolescent↗
PubMed2001

Reconstruction of the primate mandible with a combination graft of recombinant human bone morphogenetic protein-2 and bone marrow.

PURPOSE: This study evaluated whether recombinant human bone morphogenetic protein-2 (rhBMP-2) can be used to regenerate a resected part of the mandible in a primate model. MATERIALS AND METHODS: Segmental bone defects were created surgically in the mandible of Japanese monkeys. rhBMP-2 was suspended in a solution of polyglycolic co-lactic acid (PGLA) and lyophilized to make a BMP/PGLA complex. The rhBMP-2/PGLA complex and autogenous bone marrow in ratios of 3:0, 2.5:0.5, or 2:1 (vol:vol) were each implanted into the bone defects in 3 monkeys. Bone marrow or P(GLA alone were each implanted in 1 monkey as a control. The animals were killed 16 weeks after surgery, followed by radiologic and histologic evaluation. RESULTS: The implantation of bone marrow alone succeeded in reconstruction of the mandible, but the implantation of the rhBMP-2/PGLA complex showed only a small amount of bone formation. The combination graft of rhBMP-2/PGLA and bone marrow resulted in a greater degree of bone formation; especially the 2:1 combination showed the same result as only bone marrow implantation. CONCLUSION: The combination graft of rhBMP-2 and bone marrow, which requires only a small amount of bone marrow, was a reliable method for reconstruction of mandibular segmental defects in this animal model.

Animals↗
PubMed2002

Osteogenesis distraction and platelet-rich plasma for bone restoration of the severely atrophic mandible: preliminary results.

PURPOSE: The purpose of this study was to evaluate a new method of restoring severe atrophic mandible using platelet-rich plasma (PRP) during distraction osteogenesis. MATERIALS AND METHODS: Since 1999, 2 men and 3 women with severe atrophy (Cawood and Howell classes V and VI) of a completely edentulous mandible have been treated with a novel distraction procedure. During the surgery, a mixture of autologous bone graft, harvested from the iliac crest, and an autologous platelet concentrate, obtained from platelet-rich plasma, filled the distraction gap. This mixture constituted an autologous bone-platelet gel that was used to create a useful bony scaffold for distraction regenerate. After a latency period of 15 days, a distraction run of 0.5 mm/d, and a 60-day period of consolidation, the distraction device was removed and implants were placed simultaneously. RESULTS: In all treated patients, planned distraction height was achieved with a considerable enhancement of bony regeneration, and in all cases it was possible to place implants at a planned time. CONCLUSIONS: The combination of these recent and innovative regenerative methods seems to be effective in restoring the severe atrophic mandible.

Alveolar Bone Loss↗
PubMed2002

The surgical treatment of central giant cell granuloma of the mandible.

PURPOSE: The objective of this study was to report and evaluate our experience in the surgical treatment of mandibular central giant cell granuloma by resection without continuity defect and peripheral ostectomy. METHODS: A retrospective analysis was conducted of patients with central giant cell granuloma of the mandible who were treated between 1991 and 2000, in the Oral and Maxillofacial Surgery Unit at Jordan University of Science and Technology. A uniform surgical technique was used in all cases. The compact bone composed of the lower border of the mandible and/or posterior border of the ascending ramus, together with the nutrient periosteum attached to it, was preserved. All soft tissues in contact with or overlying the lesion and a margin of cancellous bone related to the lesion were excised. All patients were reviewed annually for a follow-up period of 1 to 9 years (mean, 3.9 years). RESULTS: Eighteen patients with central giant cell granuloma were included, (9 males and 9 females). Their age ranged from 10 to 46 years, with 89% younger than 40 years. Five (28%) lesions were in the incisor-canine region, 2 (11%) were confined to the premolar region, 4 (22%) were in the premolar-molar region, and 7 (39%) were in the molar-ramus region. All patients had aggressive central giant cell granulomas with pain, tooth mobility, and rapidly enlarging swelling. The initial diameter of lesions ranged from 2.7 to 10 cm. During the follow-up period, there was 1 case of recurrence, 2 (11%) patients had permanent lower lip paraesthesia, and no patient had obvious facial deformity. CONCLUSION: Our results suggest that resection without a continuity defect and peripheral ostectomy is a satisfactory method in the treatment of central giant cell granuloma of the mandible, with no or a very low recurrence rate and favorable postoperative function.

Adolescent↗
PubMed2001

Evidence for imaging the mandible in the management of oral squamous cell carcinoma: a review.

The accuracy of clinical examination, peroperative periosteal stripping and imaging techniques in predicting tumour invasion of the mandible in oral cancer so far reported have been compared according to their specificity and sensitivity. Clinical examination alone was not shown to be accurate, but periosteal stripping at the time of resection was extremely accurate although so far only one study has investigated it. No single imaging technique will accurately predict the invasion of tumour into the mandible, but a combination of an orthopantomogram and bone scintigraphy is recommended in early invasion. Magnetic resonance imaging is more sensitive than computed tomography and therefore may be more useful if mandibular invasion requires consideration. The decision to resect the mandible as part of the management of oral cancer should be taken on the evidence of clinical examination, periosteal stripping and at least two imaging techniques that complement each other in terms of specificity and sensitivity.

Adipose Tissue↗
PubMed2001

Comparison of different distraction rates in the mandible: an experimental investigation.

This study evaluated bone distracted in rabbit mandibles at different intervals and with different daily rates of distraction histologically with the goal of attaining a universally accepted distraction protocol. Osteogenesis was investigated in mandibles distracted at different rates in 24 New Zealand rabbits using a custom-made submerged distractor. Distraction was started on the third postoperative day for a total of 10 mm. The animals were divided into four groups each containing six rabbits. Group 1 was distracted 0.5 mm twice a day; Group 2 was distracted 1.0 mm once a day; Group 3 was distracted 1.0 mm twice a day and Group 4 was distracted 2.0 mm once a day. All the animals were sacrificed 6 weeks after completion of distraction. Half of the distracted mandibles were decalcified for H&E staining and polarized light microscopy studies. Sections of the undecalcified half of the samples were stained with Goldner's stain. The results indicate that a distraction rate of 1.0 mm per day produced the best osteogenesis among the tested rates. There was no great difference in osteogenesis between 1.0 mm once a day and 0.5 mm twice a day. However, 0.5-mm distraction may result in immature bone healing. Distraction of 1.0 mm twice a day resulted in incomplete osteogenesis, while distraction of 2.0 mm once a day resulted in fibrous union. It is clear from these results that a shorter period of device fixation should be achieved by methods other than rapid distraction.

Animals↗
PubMed2000

Does the sheep mandible relapse following lengthening by distraction osteogenesis?

AIM: Distraction osteogenesis is a technique used to lengthen the shortened mandible. However, the long term stability of the distracted mandibular bone is not known. The aim of this study was to assess if the sheep mandible relapses following lengthening, and to assess the quality of distracted bone up to 1 year post lengthening. METHODS: Twenty-four sheep had bilateral external mandibular distractors applied, with three sheep as controls. Titanium marker screws were positioned both proximal and distal to the distraction zone in all sheep. Following a 5 day latency period, the interdental gap was distracted 1 mm/day for 20 days, with a subsequent 20 day consolidation period. Ante-mortem serial X-rays were used to assess for relapse by measuring the distance between the screws. The animals were sacrificed at either 3, 6, 9 or 12 months post-distraction. At post mortem, the distance between the screws was re-measured. The distracted bone was assessed mechanically and histologically. RESULTS: The mean mandibular lengthening obtained was 13.2 mm. There was no relapse of the mandible over 12 months. The distracted bone had attained the strength and stiffness of undistracted bone by 6 months post-distraction (p < 0.05). Histological evaluation revealed significant amounts of lamellar bone by 6 months post-distraction. CONCLUSIONS: No relapse occurred for 12 months post distraction lengthening. The bone formed following distraction was stable and of good quality. These findings lend support to the use of distraction osteogenesis in clinical practice.

Analysis of Variance↗
PubMed2002

Matrix metalloproteinases and their inhibitors in bone remodelling following distraction osteogenesis of the sheep mandible.

AIM: Matrix metalloproteinases (MMPs), together with their tissue inhibitors (TIMPs), are responsible for the controlled degradation of collagen and other matrix substrates in bone and other tissues. This study evaluated the expression of MMPs and TIMPs in bony remodelling in a bilateral sheep mandible model up to 12 months following lengthening by distraction osteogenesis. METHODOLOGY: Sheep mandibles were harvested 3, 6, 9 or 12 months following lengthening by bilateral mandibular distraction (1 mm/day for 20 days). Undistracted sheep mandibles were used as controls. The tissues underwent routine histology and immunohistochemical staining with monoclonal antibodies specific to MMPs 1-3 and TIMP-1, 2. Matrix and cell staining was assessed using a semi-quantitative analysis. RESULTS: Matrix metalloproteinases and their tissue inhibitors (TIMPs) expression levels were marked at 3 months and decreased thereafter becoming similar to undistracted controls by 12 months. The histologic development of mature lamellar cortical bone was similar to undistracted controls by 9 months following distraction. CONCLUSIONS: A temporal expression of MMPs and TIMPs was found in distraction osteogenesis. MMPs and TIMPS may, in part, reflect the state of bony remodelling following mandibular lengthening by distraction osteogenesis. Matrix metalloproteinases and TIMP expression were comparable to undistracted controls by 12 months, suggesting that equilibrium had been achieved and that bony relapse is unlikely.

Animals↗