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PubMed1991

Effect of size of region of interest on precision of bone mineral measurements of the mandible by quantitative computed tomography.

The effect of size and shape of the region of interest (ROI) on the precision of the measurements of bone mineral content of mandibular bone by quantitative computed tomography (QCT) has been studied. A dry mandible and a series of calcium carbonate rods (density: 119.6 mg cm-3, 461.2 mg cm-3 and 939.0 mg cm-3) were used. The precision of measurements of the ROI for sizes less than 1 cm2 was very low, but the shape did not have any influence on the precision if the material examined was either homogeneous or if it was heterogeneous from always the same area. Higher precision was found when the ROI was more than 1 cm2. The size of ROI is a critical factor in the measurement of bone mineral content in the mandible by QCT.

Bone Density↗

PubMed1996

Observations on the vascular structure of malignant tumours of the mandible using specimen arteriography.

OBJECTIVES: To investigate the vascular structure of different malignant tumours of the mandible. METHODS: Specimen arteriography was performed on seven cases of squamous cell carcinoma of gingiva and four sarcomas. RESULTS: Malignant tumours could be divided into two groups: (1) the hypervascular sarcomas in in which the arteries were dilated, distributed evenly and arranged in a bush-like pattern; and (2) hypovascular squamous cell carcinoma with scanty arteries distributed unevenly without dilatation; in some areas, the shape of arteries was irregular and arranged in a network pattern. CONCLUSIONS: The variation in vascular structure of malignant tumours of the mandible may be related to the outcome of regional chemotherapy.

Adolescent↗

PubMed2004

Trabecular alveolar bone microarchitecture in the human mandible using high resolution magnetic resonance imaging.

OBJECTIVES: Cancellous bone microarchitecture in the mandible can influence the success of dental implant osseointegration. The aims of this study were to explore the feasibility of two-dimensional (2D) high resolution magnetic resonance imaging (MRI) for the evaluation of trabecular bone architecture and to compare architecture parameters derived from MR images between different areas in the mandible, and between sex and dental status. METHODS: 45 mandibular bone specimens (8 mm thickness) were cut from 15 fresh cadavers. MR images were obtained at 2 T using a multislice 2D spin-echo sequence. After MR image binarization, histomorphometry parameters, i.e. bone area fraction (BAF), specific perimeter (La), trabecular bone width (Tb.Wi), trabecular bone separation (Tb.Sp) and trabecular network anisotropy (R), were computed from the mean intercept length. The angle between trabeculae and tooth axis and the Euler-Poincaré characteristics (EPCs) were also computed. RESULTS: BAF, Tb.Wi and R were significantly higher in male specimens compared with female specimens, whereas Tb.Sp was significantly lower. The apparent Tb.Wi was found to be significantly higher in dentate specimens compared with edentulous ones. The highest anisotropy, corresponding to the smallest R value, was seen in the incisal specimens. The preferential orientation of the trabeculae was close to perpendicular to the tooth axis, especially in the molar specimens. CONCLUSION: BAF, La, Tb.Wi, Tb.Sp and R, the most variable parameters, may potentially have a relationship with the biomechanical competence of trabecular bone and play a role both in primary stabilization of dental implant and the time needed before loading.

Absorptiometry, Photon↗

PubMed1998

Multivariate analysis of mandible in the Ryukyu wild pig (Sus scrofa riukiuanus).

We measured adult mandibles of Ryukyu wild pig (Sus scrofa riukiuanus) from Tokunoshima Island and compared the osteometrical data with those from six Nansei Islands. The mandibles in Tokunoshima Island were larger than those from Amami-Oshima and Okinawa Islands in some measurements. We concluded that the size cline was not statistically recognized among populations. In the principal component analysis, the size cline was also denied, and the separation could be made among island populations in female. It is suggested that the populations in Tokunoshima and Okinawa Islands may be different from those in Amami-Oshima, Kakeroma, Ishigaki and Iriomote Islands in skull proportion.

Aging↗

PubMed2005

Hemangiomatosis associated with osteolysis of the mandible in a dog resembling Gorham-Stout disease in humans.

A 6-month-old female German Shepherd Dog died as a result of profuse oral bleeding. At postmortem examination, the oral cavity showed visible roots of the right mandibular fourth premolar and first molar teeth and, in addition, they were very mobile and compressible. Radiographs showed a generalized radiolucency in the body of the right mandible, with evidence of resorption of the affected alveolar bone. Histologically, the lesion of the right mandible was characterized by the lysis of bony structures and a non-malignant proliferation of blood-filled vascular spaces lined by a single layer of well-differentiated endothelial cells. The clinical, radiographic, and histologic presentation of this dog is consistent with that associated with Gorham-Stout disease, a rare bone disorder in humans.

Animals↗

PubMed2005

Expression of versican and ADAMTS1, 4, and 5 during bone development in the rat mandible and hind limb.

Extracellular matrix (ECM) remodeling is achieved by both production and degradation of ECM molecules during bone development. ADAMTS (a disintegrin and metalloprotease with thrombospondin type 1 motifs) constitutes a family of extracellular proteases which are implicated in cleaving the protein versican. The present study was designed to investigate the expression of versican and ADAMTS1, 4, and 5 mRNA during bone development in rat mandibles and hind limbs by RT-PCR and in situ hybridization. Versican was localized by immunohistochemistry. The process of bone development from day 14 postcoitum through week 6 postnatum was divided into the beginning of osteogenesis, woven bone, and lamellar bone stages. Versican protein was abundant in the woven bone matrix, but decreased in the lamellar bone matrix. Versican mRNA was prominent in some osteoblasts with corresponding localization of the cognate protein. The temporal and spatial mRNA expression pattern of ADAMTS1, 4, and 5 was comparable to that of versican. These results suggest that woven bone rich in versican alters into lamellar bone containing little versican during bone development in both mandibles and hind limbs, where some osteoblasts may be involved in production as well as degradation of versican by secreting ADAMTS1, 4, and 5.

ADAM Proteins↗

PubMed2002

Densitometric study of dry human mandible.

The purpose of this study was to evaluate the variability of bone density among three zones of adult human dry mandible and its relationship to age, gender, and dental status. Thirty-one dried mandibles (16 female ranging between 23 and 82 yr and 15 male ranging between 34 and 85 yr; 6 samples completely edentulous and 6 edentulous only in the molar-premolar zone) were analyzed by a Hologic QDR 1000 X-ray densitometer according to three zones: the ramus, the molar-premolar zone, and the incisor-canine zone. We found a significant inverse correlation between bone density of the ramus and age (r = 0.41, p = 0.02). The bone density of the incisor-canine zone was higher than the density of the other zones; males had a higher bone density than females in all zones analyzed. Our data suggest that mandibular bone density is influenced by age and gender in different ways according to the specific mandibular portion considered, whereas the dental status does not seem to influence mandibular bone density.

Adult↗

PubMed2004

Immediate loading of dental implants in the edentulous mandible.

BACKGROUND: The authors review the literature regarding immediate implant loading in the anterior edentulous mandible, demonstrate the technique they currently use, review preliminary results and present an illustrative case. MATERIALS AND METHODS: The authors conducted a literature search using PUBMED and Ovid databases. They considered for review 31 articles in English from 1969 to 2003 that pertained to immediate loading of the anterior mandible. The authors developed a technique to provide a bar-supported prosthesis on the day of surgery. They treated five patients and followed them up for at least six months. The preliminary results are presented. RESULTS: This literature review demonstrated that immediate loading of anterior mandibular implants is an acceptable method, with predictable results. This case series demonstrates the potential for delivering a final bar on the day of surgery, based on the current evidence and clinical application. CONCLUSIONS AND PRACTICE IMPLICATIONS: The method described provides patients with immediate prosthetic restorations and a decreased treatment time compared with that for the traditional two-stage implant approach.

Dental Implantation, Endosseous↗

PubMedDate not supplied

[Numerical simulation (FEM) of the human mandible: validation of the function of the masticatory muscles].

The article describes part of a research project aiming to develop a new modular software tool for the individual dynamic numerical simulation of the human mandible using the finite element method (FEM). Its planned use in the clinical setting makes it very important to validate the results of the simulations. Here, the function of the masticatory muscles is to be tested. On the basis of biomechanical data from the literature, standard movements, such as closing the mouth, forward movement, lateral movement or backward movement, were dynamically simulated. Apart from muscle activity, the movements of the mandible are defined by the temporomandibular joint. At present, translating the condylar dynamics to the simulation still poses problems. For this reason, therefore, simulations of the two extreme cases "fixed" and "force-free" condyles are compared. While in the case of fixed condyles, some of the movements could be reproduced either not at all or only weakly, in the case of force-free condyles, all standard movements were reproduced qualitatively, albeit without the guiding effect of the joint capsule or the articular disc.

Biomechanical Phenomena↗

PubMed1999

Antiangiogenic therapy of a recurrent giant cell tumor of the mandible with interferon alfa-2a.

We report a 5-year-old girl with a large rapidly growing giant cell tumor of the mandible that recurred 2 months after the first surgical excision and 3 months after a second resection. An angiogenic protein, (bFGF), was abnormally elevated in her urine. The patient was treated with interferon alfa-2a for 1 year because this agent inhibits angiogenesis by suppressing bFGF overexpression in infantile hemangiomas and in other human tumors. During this time the bone tumor regressed and disappeared, the urinary bFGF fell to normal levels, and the mandible regenerated. She has remained tumor-free and has been off therapy for 3 years at this writing. This first successful use of interferon alfa-2a to treat a mandibular tumor in a child demonstrates: 1) low grade tumors that overexpress bFGF may respond to interferon alfa-2a, in a manner similar to life-threatening infantile hemangiomas; 2) antiangiogenic therapy, given without interruption for 1 year, was safe and effective in this patient; and 3) treatment may be continued for 1 year without the development of drug resistance.

Antineoplastic Agents↗

PubMedDate not supplied

[Radiographic assessment of the anterior height of the mandible after vestibuloplasty with the lipswitch technique: study with humans].

The aim of this study was to determine, through cephalometric analysis, the anterior height of the mandible after vestibuloplasty through the lipswitch technique. Thirteen patients (8 women and 5 men) with ages between 32 and 77 years (mean age of 54.3 years) were evaluated. The postoperative periods were 30, 90 and 180 days. During this time there was a reduction of 0.6 mm in the anterior height of the mandible, which was not significant.

Adult↗

PubMed2006

Early postnatal development of the mandible in children with isolated cleft palate and children with nonsyndromic Robin sequence.

OBJECTIVE: Analysis of early postnatal mandibular size and growth velocity in children with untreated isolated cleft palate (ICP), nonsyndromic Robin sequence (RS), and a control group of children with unilateral incomplete cleft lip (UICL). MATERIAL: 114 children (66 isolated cleft palate, 7 Robin sequence, 41 unilateral incomplete cleft lip) drawn from a group representing all Danish cleft children born from 1976 through 1981. All children were examined at both 2 and 22 months of age. METHODS: Cephalometric x-rays and maxillary plaster casts. Mandibular length and height were measured and mandibular growth velocity (mm/year) was calculated. Cleft width was measured on the casts at 2 months of age. RESULTS: Mean mandibular length and posterior height were significantly smaller in isolated cleft palate and Robin sequence, compared with unilateral incomplete cleft lip. Mandibular length in Robin sequence was also significantly shorter, compared with isolated cleft palate. No significant difference was found between mean mandibular growth velocities in the three groups. No significant correlation was found between mandibular length and cleft width in either isolated cleft palate or Robin sequence at 2 months of age. CONCLUSION: The children with isolated cleft palate and Robin sequence had small mandibles shortly after birth, but with a relatively normal growth potential. No true mandibular catch-up growth was found up to 22 months of age in either group. No significant correlation was found between mandibular size and cleft width in either group at 2 months of age. However, there was a significant trend toward the shorter the mandible, the more severe the sagittal extension of the cleft.

Age Distribution↗

PubMed2001

Displacement of the mandible in a child with congenital unilateral temporomandibular joint ankylosis treated with two-stage condylar replacement: a long-term study with the aid of roentgen stereometric analysis.

OBJECTIVE: To monitor mandibular displacement in three dimensions with a high degree of accuracy before, during, and after treatment. DESIGN: Prospective roentgen stereometric analysis from age 3 years 7 months to age 13 years 8 months. SETTING: Center for Craniofacial Anomalies and Department of Maxillofacial Surgery, Malmö University Hospital, Malmö, Sweden. PATIENT: Girl with unilateral congenital temporomandibular joint (TMJ) ankylosis and marked facial asymmetry. INTERVENTIONS: Epipharyngeal inspection at age 2 years 6 months and insertion of implants under general anesthesia. Resection of the affected right condyle at age 5 years 4 months, replacement of the ramus-condyle complex with a custom made titanium prosthesis at age 5 years 5 months, and replacement of the artificial condyle by a costochondral graft at age 9 years 7 months. Roentgen examinations were performed at intervals from age 3 years 7 months to age 13 years 8 months. Body length was measured annually. MAIN OUTCOME MEASURES: Stereo roentgenograms were digitized by the Department of Orthopedic Surgery, Malmö University Hospital. RESULTS: Unexpected lowering of the mandible occurred before treatment. Each procedure had a distinct effect on the direction of mandibular displacement. There was little or no pathological involvement of the functional matrix. Growth of the costochondral graft exceeded growth of the unaffected TMJ. Anterior displacement as well as rotation and tilting of the mandible to the unaffected side accelerated after the age of body peak height velocity. CONCLUSIONS: Accurate monitoring of mandibular displacement may contribute to a rationale for clinicians' decision on treatment protocol and reveal compensatory differential growth.

Adolescent↗

PubMed1984

The prevalence and distribution of intrabony defects in dry mandibles.

One hundred mandibles of South African Negroes were examined for the presence of intrabony defects, and the distance between the cemento-enamel junction and alveolar bone crest was measured along the buccal and lingual surface of roots associated with interdental craters. Two-hundred thirty-one intrabony defects were detected (4.1% of the possible occurrences). There were 51 craters, 19 of which were associated with the distal surfaces of the second molars. Most craters (84.3%) had higher lingual than buccal walls. Seventy-one defects (35.8%) were one-walled pockets, 98 defects (49.6%) were two-walled pockets and 30 (15%) were three-walled pockets. Twenty-eight one-walled pockets (39.4%) formed hemisepta against interproximal root surfaces. Mesial surfaces of canines were the most commonly involved with hemisepta. There was an increase in the frequency of intrabony pockets from the anterior to the posterior zones of the mandibles. Interproximal root surfaces were by far more commonly associated with defects than buccal or lingual surfaces.

Adult↗

PubMed1994

Regional accelerated phenomenon in the mandible following mucoperiosteal flap surgery.

Striking remodeling activity occurs adjacent to the site of injury in orthopedic surgery. This reaction has been described as regional accelerated phenomenon (RAP), as it speeds up the healing stage. The phenomenon is a transient burst of localized remodeling process following surgical wounding of cortical bone. We explored whether RAP occurs following mucoperiosteal flap surgery in the jaw bone. Mucoperiosteal flaps were performed on 60 Wistar rats, either only on the buccal aspect or both on buccal and lingual aspects of the mandible. The surgical procedure lasted an average of 30 seconds and the flap was readapted without sutures. The rats were sacrificed at 3, 7, 10, 14, 21, and 120 days. High resolution x-ray microradiography of 1 to 1.5 mm thick ground sections between premolar and molar regions of the mandible were analyzed and revealed large areas of radiolucency which correlated to massive resorption of the alveolar bone, as well as areas in the bone proper. The RAP was observed as early as 10 days in the treated side group. Striking resorption of the cortical bone, both on the surface and the bone proper, occurred on the periodontal aspect of the crestal bone leading to widening of the periodontal ligament space, where a mucoperiosteal flap was performed on the buccal aspect. The resorption was more prominent when a mucoperiosteal flap was performed both on the lingual and buccal aspect. The alveolar bone recovered almost to control levels 120 days after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗

PubMed2003

Peri-implant soft tissue integration of immediately loaded implants in the posterior macaque mandible: a histomorphometric study.

BACKGROUND: Today, one critical goal in implant placement is the achievement of optimal soft tissue integration. Reports thus far have demonstrated successful soft tissue preservation in delayed loaded implants placed in anterior jaws. The aim of this study was to histomorphometrically examine the soft tissues around immediately loaded implants placed in the macaque posterior mandible. METHODS: Splinted crowns on screw-shaped titanium implants (8 mm length, 3.5 mm diameter) were utilized. Three implants each were placed in the premolar-molar edentulous mandibular segments of 6 adult monkeys (Macaca fascicularis); one side served as the control (delayed loading) and the other as the test sites (immediate loading). The animals were sacrificed after 3 months of loading. Histomorphometry of 6 soft tissue indices including the sulcus depth (SD), junctional epithelium (JE), connective tissue contact (CTC), biologic width (BW = SD + JE + CTC), DIM (distance between the implant top and coronal gingiva), and DIB (distance between the implant top and first implant-to-bone contact) was performed on non-decalcified sections. RESULTS: No significant differences in the mean soft tissue scores (mm) between the test (SD = 0.68 +/- 0.63; JE = 1.71 +/- 1.04; CTC = 1.51 +/- 1.14; DIM = 2.27 +/- 1.18; DIB = 1.32 +/- 1.21; BW = 3.9) and control (SD = 0.88 + 0.57; JE = 1.66 + 0.77; CTC = 1.24 +/- 0.92; DIM = 2.38 +/- 0.81; DIB = 1.19 +/- 0.91; BW = 3.78) groups were observed (P > 0.01). CONCLUSION: These findings suggest that the dimensions of the peri-implant soft tissues were within the biologic range and were not influenced by immediate functional loading or posterior location of the implants in the macaque mandible.

Alveolar Process↗

PubMed2004

Hemorrhaging associated with endosseous implant placement in the anterior mandible: a review of the literature.

The placement of endosseous dental implants is largely considered a safe surgical procedure. However, upper airway obstruction secondary to severe bleeding in the floor of the mouth has been occasionally reported as a rare but potentially fatal complication of implant surgery. This review presents critical hemorrhagic episodes, related to dental implantation in the anterior segments of the mandible, published to date. Massive internal bleeding in the highly vascularized region of the floor of the mouth is the result of an arterial trauma induced by instrumentation, usually through a perforation of the lingual cortical plate. Depending on the clinical situation, hemorrhage may commence immediately or with some delay after the vascular insult. The progressively expanding lingual, sublingual, submandibular, and submental hematomas have the tendency of displacing the tongue and floor of the mouth to obstruct the airway. Because the course of airway deterioration to complete occlusion may be rapid, ensuring a patent airway is of highest priority. Even though upper airway obstruction is potentially life-threatening, a secure airway was successfully established in all patients without fatal consequences. In most cases, resolution of hemorrhage required a surgical intervention for ligation of the bleeding vessels and hematoma evacuation. To reduce the probability of such a grave complication, preventive and precautionary measures to be taken before, during, and after implant placement in the anterior mandible are presented. Issues related to the level of surgical experience, fine regional arterial anatomy, radiographic and clinical evaluation of the osseous morphology, angulation and length of implants, and timing of hemorrhage onset are discussed. In addition, airway and bleeding management strategies are provided.

Airway Obstruction↗

PubMed2005

[Implant-supported restoration in the free-end partially edentulous mandible: a clinical report].

PATIENT: A 60-year-old woman presented to the Clinic at Health Science University of Hokkaido on September, 1997. The patient's chief complaint was difficulty in chewing due to pain with tooth clenching of a fixed partial denture in the left mandible. This clinical report describes a treatment approach using implant-supported fixed prostheses by two dental implants after extraction of the abutment teeth. DISCUSSION: She tried to use the fabricated mandibular removable partial denture but disliked the lingual bar. After discussing a treatment plan using implant-supported fixed prostheses, a decision was made to place implants in the free-end partially edentulous mandible. CONCLUSION: The patient was followed for 4 years with no surgical or prosthetic complications. It is suggested that a dental implant for prosthetic treatment may improve the quality of life of the patient.

Dental Prosthesis, Implant-Supported↗