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Two developing supernumerary bicuspids were noticed accidentally in the mandible of a 12 years old girl when evaluating an impacted 35 on a radiograph. The development of these teeth was followed, but at a later stage they were removed. In a 17 years old man multiple complete developed bicuspids were seen on a radiograph. The backgrounds and treatment concerning supernumerary bicuspids in the mandible are discussed.
The thickness of the substantia compacta and the volume and width of the trabecular bone of the substantia spongiosa were investigated by soft X-ray photographs made of thin sections of many kinds of dentulous and edentulous mandibles. The results were: 1) The thickness of substantia compacta is especially thick on the lingual side in the incisor region and thickest in the molar region in all materials. At the base of mandible, the thickness is essentially the same in all regions, but, the thickness of dentulous materials is greater than of edentulous ones. 2) On the upper part, the volume of trabecular bone is less in the premolar region in both edentulous and dentulous material than in other regions, however, there is relative more in edentulous than in dentulous. In the central part, there is almost the same amount of trabecular bone in the dentulous and edentulous material. 3) The width of the trabecular bone in the substantia spongiosa is greater in the incisor region than in other regions in all materials. In the upper and central part, it is smaller in the premolar region in both edentulous and dentulous material but, it increases in the molar region in the edentulous materials.
A 4-year-old llama had an aggressive, multiloculated, expansile bone lesion involving the rostral mandible. The mandibular lesion was imaged using radiography and computed tomography. Antemortem diagnosis of an ossifying fibroma was made histologically. Postmortem findings showed the lesion to be limited to the mandible. Final diagnosis was ameloblastic odontoma.
OBJECTIVE: To detect the effect of genistein on mandible metabolism in ovariectomized rats. METHODS: Forty 12 week-old female SD rats were randomly assigned to four groups: (1) sham operated; (2) ovariectomized; (3) ovariectomized and treated with estradiol; (4) ovariectomized and received genistein, 45 mg/kg body weight per day. After 12 weeks, bone mineral density (BMD), serum level of alkaline phosphatase (ALP), acid phosphatase (ACP), osteocalcin, IL-1beta, TNF-alpha, IL-6 and calcitonin (CT) were evaluated. In addition, the serum estradiol and the weight of uteri were also examined to indicate the side effect of genistein to the uteri. RESULTS: Ovariectomized animals had a significant decrease in BMD, and increased serum level of ALP, ACP, IL-1beta and osteocalcin compared with sham rats. After treated with genistein, BMD and the serum level of ALP, ACP, osteocalcin increased significantly, while the serum level of IL-1beta and TNF-alpha decreased. Especially, the increase of ALP and osteocalcin was higher than that of estradiol-treated animal. Additionally, the uterus weight index and the serum estradiol in genistein-treated rats were lower significantly than those of estradiol-treated rats. CONCLUSIONS: Genistein can improve the mandible bone metabolism as well as its effect on femur through the promotion of bone formation and the prevention of bone resorption with slight side effect. Genistein provides an additional viable way to therapy for osteoporosis in the jaw bones.
PURPOSE: In patients with atrophic mandibles, elevation of the floor of the mouth often prevents intraoral rectangular radiography for longitudinal follow-up studies, while extraoral techniques such as panoramic radiographs tend to produce distorted views of the interforaminal region. In this study, intraoral rectangular radiographs and panoramic radiographs were compared for their accuracy in evaluating peri-implant bone loss. MATERIALS AND METHODS: In a recall program, 22 patients with 88 screw-type implants (44 MKII and 44 Frios) were followed. Interforaminal marginal bone loss was evaluated by extraoral orthopantomograms and by intraoral rectangular radiographs. In addition, pocket depth, Periotest readings, and bleeding on probing were recorded. For statistical analysis, the Spearman coefficient of correlation was used. The effects on bone loss and clinical variables were computed with a mixed model and the Bland and Altman method. RESULTS: Computed as least square means, the mean difference between panoramic radiographs (2.4 +/- 0.2 mm for MKII implants and 1.6 +/- 0.2 mm for Frios implants) and intraoral radiographs (2.6 +/- 0.2 mm and 1.4 +/- 0.2 mm, respectively) was 0.2 mm (range, 0.1 to 0.8 mm). DISCUSSION: In this study, the 2 imaging techniques were comparable clinically in terms of the precision with which they could be used to measure marginal bone loss. CONCLUSION: For highly atrophic mandibles with unfavorable imaging conditions, rotational panoramic radiographs can be a useful alternative to intraoral small-format radiographs for evaluating peri-implant bone loss.
PURPOSE: The condition and character of stress distribution in the mandibular in normal human being during centric, protrusive, laterotrusive occlusion were analysed. METHODS: The three-dimensional finite element model of the mandibular was developed by helica CT scanning and CAD/CAM software, and three-dimensional finite element stress analysis was done by ANSYS software. RESULT: Three-dimensional finite element model of the mandibular was generated. Under these three occlusal conditions, the stress of various regions in the mandible were distributed unequally, and the stress feature was different;while the stress of corresponding region in bilateral mandibular was in symmetric distribution. The stress value of condyle neck, the posterior surface of coronoid process and mandibular angle were high. CONCLUSION: The material properties of mandible were closely correlated to the value of stress. Stress distribution were similar according to the three different loading patterns, but had different effects on TMJ joint. The concentrated areas of stress were in the condyle neck, the posterior surface of coronoid process and mandibular angle.
PURPOSE: In this retrospective study, marginal peri-implant bone height around machined and sandblasted/acid-etched interforaminal implants in the mandible was evaluated radiologically at least 3 years after functional loading. MATERIALS AND METHODS: Fifty-one patients, each with 4 interforaminal screw-type implants placed between 1994 and 1998, were included in this study. Of these, 36 patients (70.6%) with a total of 144 implants (76 machined Mk II implants and 68 sandblasted/acidetched Frios implants) were available for follow-up studies. Interforaminal marginal bone loss was evaluated by extraoral rotational panoramic radiographs. In addition, predictive factors such as patient age and sex, nicotine use, implant position, implant life, and site of measurement were recorded, as well as bone loss at surgery (ie, baseline bone loss). Analysis of covariance for repeated measurements was used for statistical analysis. Between-group differences were expressed as least square means +/- standard error. RESULTS: Sandblasted/acid-etched implants showed significantly less marginal bone loss than machine-surfaced implants (2.4 +/- 0.23 mm vs 1.64 +/- 0.27 mm). Implants placed in the anterior of the arch showed significantly more peri-implant bone loss than implants placed in the posterior (P = .0001). DISCUSSION AND CONCLUSIONS: Significantly less long-term peri-implant bone loss was observed for rough implant surfaces compared to machine-surfaced implants. However, it was also demonstrated that both types of implants, in combination with bar-supported overdentures, can produce excellent long-term results in the atrophic edentulous mandible. Mesially placed implants showed more bone resorption than distally positioned implants, independent of surface roughness.
PURPOSE: This work compared implant-supported fixed prostheses and overdentures in the edentulous mandible in a randomized prospective study of treatment results, clinical working hours, laboratory working hours, and laboratory costs including materials. MATERIALS AND METHODS: Seventeen subjects agreed to participate. Three standard Brånemark implants were placed between the mental foramina in each patient. After the connection of standard abutments, subjects were randomly assigned to the fixed prosthesis group (n = 11) or overdenture group (n = 6). Subjects in the fixed group were provided with prostheses according to the All-in-One concept. Subjects in the overdenture group received a conventional denture retained by a Dolder bar system. RESULTS: One implant was lost in the fixed prosthesis group after 1 year. A new implant was placed, and the prosthesis was refitted. Mean clinical working hours were 3.1 in the fixed prosthesis group and 4.1 in the overdenture group. Mean laboratory working hours were 12.5 in the fixed prosthesis group and 7.7 in the overdenture group. Total laboratory costs, including materials, were on average about 1,700 US dollars for the fixed prosthesis and 1,350 US dollars for the overdenture. CONCLUSION: A fixed implant-supported prosthesis in the edentulous mandible could be provided at about the same cost as an overdenture using the method described. Provided that the early survival results prove to be long lasting, the choice between a fixed and a removable prosthesis need not be a matter of economy.
Mandible defects can be caused by many diseases, most commonly occurring in cranio-maxillofacial regions. With the development of orthopaedics, biomaterial and cell biology in these years, great improvements have been acquired in repair of mandible defects. This paper systematically reviewed the relevant research advances and applications, and showed the applied prospect of bone tissue engineering in this field.
Retrusion of the mandible is of central importance to the diagnosis and therapy of functional discorders of the orofacial system. The change in width of the mandible is measured during recording this retruded position, and instructions for an appropriate mode of procedure are given.
Red blood cell mass has been shown to recover rapidly with great decreases, as occurs in orthognathic surgery. However, blood loss during bilateral sagittal split osteotomy is considered minimal. The purpose of this study was to verify changes in hemoglobin (Hb) and hematocrit (Ht) levels following orthognathic surgery of the mandible. Data from 12 patients with a mean age of 27.5 years, from both genders, that were submitted to bilateral sagittal split osteotomy in the prognathism reduction were evaluated. No patient received blood transfusion during the procedure nor postoperatively. Procedures were performed by the same surgeon, with the use of reciprocating and sagittal saws. Levels of Hb and Ht were obtained in preoperative, one day postsurgery, and one, three and six weeks postoperatively. Statistical analyses were used to verify the difference in each group, and between periods. Patients lost a mean decrease in Hb of 2.0 g/dl, and in Ht of 5.2%. There was significant difference as to the levels of Hb (p=0.002) and Ht (p=0.010). These levels presented significant changes from immediate postoperative to six weeks for Hb, and to three weeks for Ht. It was concluded that a slow recovery of hemoglobin and hematocrit levels occurred following orthognathic surgery of the mandible.
The mandible is one of the most important bones of the face, by its function in the temporomandibular joint and by its role in the facial aesthetics. From this reason, our article makes some measurements on the mandible (the mandibular length, the bicondylar breath and the mandibular index). We made the measurements on 20 masculine and feminine skulls.
OBJECTIVE: The purpose of this study was to investigate the distribution of collagen I, II , X, alkaline phosphatase (ALP) and their roles during initiation of condylar cartilage of the fetal mouse. METHODS: Coronary sections of mandible of mouse embryo aged from 14th to 18th day were studied under light microscope after stained by immunohistochemical method with antibody of types I, II, X collagen and ALP. RESULTS: On the 14th day of mouse embryo, it was found that mesenchymal cells condensation continuous with the periosteum. Type I collagen and ALP were positive behind the terminal of the ossifying mandibular periosteum where future condylar will form. On the 15th day, positive staining for types I, II collagen was found in mesenchymal cells around hypertrophic cells and type X collagen was detected in hypertrophic cells. ALP was positive in both mesenchymal cells and hypertrophic cells. On the 16th day, type I collagen was observed from periosteal osteogenic cells and mesenchymal cells of the fibrous cell layer to the upper hypertrophic cell layer while Type II collagen was restricted from the lower polymorphic cell layer to the bottom of the hypertropic cell layer. Type X collagen was positive in the hypertrophic cell layer. ALP was positive in periosteal osteogenic cells and hypertrophic chondral cells, but not in the polymorphic cell layer. CONCLUSION: Development of condylar cartilage is different from that of limb bone. Types I, II, X collagen are expressed in the condylar chondrocyte on the early stage of endochondral ossification. The histology evidence supports the conjecture that condylar cartilage is derived from differentiated mesenchymal cells of the preperiosteum or periosteum of the mandible where ALP is positively expressed.
PURPOSE: To investigate whether ultrasound can stimulate osteoconduction in the mandible, an attempt was made to stimulate the osteoconductive process with low-intensity pulsed ultrasound in rats. MATERIALS AND METHODS: In 64 rats, a 5.0-mm diameter circular mandibular defect was made in the ramus and, subsequently, covered on both sides with collagen membranes. Two groups were studied, an ultrasound treatment group and a placebo treatment group. At 2 and 4 weeks, the remaining defect area was measured using microradiographs, and the amount of osteoconduction was expressed as the percentage of defect closure. RESULTS: At 2 and 4 weeks, there was no significant difference in the percentage of defect closure between the groups. DISCUSSION: An explanation may be that ultrasound does not exert an effect in an area where wound healing is already expected to be at an optimal level. CONCLUSION: There was no evidence that low-intensity pulsed ultrasound stimulates osteoconduction in a bone defect in the rat mandible that is covered by a collagen membrane.
OBJECTIVE: To study the influence of radiotherapy on immediate reconstruction with the titanium plate after resection of mandible in oral cancer patients. METHODS: Fifty-eight cases (radiation group, 30 patients and control group, 28 patients) with titanium plate for immediate reconstruction of mandibular defects were observed from January, 1997 to May, 2002. The patients of radiation group underwent radiotherapy with total doses of 4,050 - 6,540 cGy (mean 5,495 cGy). The titanium plate was in radiation fields and was irradiated during the radiation therapy. RESULTS: Local infection and fistula accounted for 6 cases and plate exposure accounted for 5 in radiation group. Local infection and plate exposure happened in 4 and 3 patients in control group respectively. Titanium plates were taken in six cases in radiation group and 4 cases in control group by re-surgery 4 - 15 months after primary surgery because of local infection. The success rates of immediate reconstruction with the titanium plate were 80.0% (24/30) in radiation group and 85.7% (24/28) in control group (P > 0.05). CONCLUSIONS: The cases of immediate reconstruction with the titanium plate after resection of mandible in oral cancer patients can accept postoperative radiotherapy.
The edentulous mandible fractures are rare representing less then 5% in the majority of series. Their treatment represents nevertheless a challenge. The bone atrophy that happens in this situation is related with the higher incidence of treatment complications demanding some special attention to the therapeutic options. In contrast with the dentulous mandibles, tension and compression zones are in close proximity, allowing the application of only one plate for the fracture treatment. It is preferable to use screws without pretapping, and the rule that the weaker the bone, the stronger the plate must be is used, associated with the cautious use of cancellous bone grafting whenever the atrophy is marked or some bone is missing. Only with these measures is possible to reduce.
OBJECTIVE: The aim of this study was to investigate how to model an accuracy 3-dimension Finite Element Analysis (3D-FEA) model. METHODS: Based on computed tomography (CT) scan data of a woman, a 3D finite element model of the first molar on the left was rebuilt by computer imagines process and computer aided design (CAD). Analysis of the stress distribution on a cylinder dental implant and in the bone around it was conducted. RESULTS: The stress distribution showed extremely asymmetry in bucco-lingual section: stress concentrated on the lingual side of the mandible; stress mainly was tensile in buccal side, and on the contrary compressive in lingual side. CONCLUSION: The results were more reliable because this model more really displayed the mandible.
Observations were made on 299 dry human mandibles and 21 autopsy heads. Foramina were observed in the inner surface of the alveolar part in 32% of the mandibles investigated. The diameter of the foramina varied between 0.4 mm and 1.6 mm. In most instances foramina were present between the lower medial and lateral incisors but in some cases they were also observed in the midline or between the lower lateral incisors and canines. Histological studies confirmed the presence of a neurovascular bundle in the accessory foramina. This bundle was formed by branches of the mylohyoid nerve, sublingual artery and accompanying veins.