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At least 631 records · Page 35Linked to original sources
PubMed1999

Osteometry of the mandible performed using dental MR imaging.

BACKGROUND AND PURPOSE: On cross-sectional and panoramic reformatted images from axial (dental) CT scans of the mandible it may be difficult to identify the inferior alveolar neurovascular bundle (IANB) in patients lacking a clear-cut bony delimitation of the mandibular canal. Dental MR images are comparable to dental CT scans, which directly show the IANB; however, measurements of length may not be reliable owing to susceptibility artifacts and field inhomogeneities in the oral cavity. Therefore, the accuracy of length measurements on dental MR images was compared with that on dental CT scans and direct osteometry. METHODS: Dental T1-weighted MR imaging using a high-resolution turbo gradient-echo sequence and dental CT were performed in six anatomic specimens. The axial scans were reformatted as panoramic and cross-sectional reconstructions on a workstation and characteristic cross sections were obtained from all mandibles. The longest axis in the bucco-lingual and apico-basal directions, the distances from the top of the mandibular canal to the top of the alveolar ridge and from the bottom of the mandibular canal to the base of the mandible, and the diameter of the bone cortex at the alveolar ridge were measured with direct osteometry on the cross sections and compared with measurements on corresponding MR and CT reformatted images. RESULTS: The correlation between direct osteometry and dental MR and CT was strong, except for the bone cortex diameter at the top of the alveolar ridge, where only a moderate correlation was found. Means of comparable length measurements were not significantly different among the three methods. CONCLUSION: The accuracy of length measurements in the jaw bones obtained using dental MR is comparable to that of dental CT and is not significantly different from direct osteometry. Thus, dental MR is a potential alternative to CT for dental imaging.

Alveolar Process↗
PubMed1999

Tooth-borne distraction of the mandible. An experimental study.

Two mini-pigs and 6 micropigs were fitted with a dentally fixed device for osteodistraction of the mandible. Following bilateral osteotomy and after a latency period of 7 days, the apparatus was activated 1 mm per day. A 9 mm lengthening of the mandible was achieved. After a retention period of 6 weeks, the device was removed followed by a consolidation period of 6 weeks. During the experiment, the callus and bone formation and potential dental and periodontal reactions were radiologically examined. Polychrome sequential labelling was performed by injecting calcein green and xylenol orange for histological assessment of bone. The animals were killed at the 14th postoperative week and the area of distraction and the roots of the adjacent teeth were histologically studied. After 12 weeks, the osteogenesis in the distraction gap was complete, showing lamellar bone. No detrimental effects at the roots or in the periodontium of the adjacent teeth were seen. Thus, lengthening or widening of the mandible using a tooth-borne distraction device seems feasible in selected cases.

Animals↗
PubMed2000

Vertical distraction of the severely resorbed mandible. The Groningen distraction device.

In this paper, both the surgical procedure and the clinical results of a novel distraction device to augment a severely resorbed anterior edentulous mandible are described. The distraction device is non-voluminous, and consists of two distraction screws and one guide screw. Two months after the last day of distraction, both distraction screws are replaced by endosseous implants and the guide screw is removed. Three months after implantation, the prosthetic treatment can be started. So far three patients have been treated. In all patients, the severely resorbed mandible (mandibular height in the canine region: 5, 6 and 7 mm, respectively) could be sufficiently enlarged to enable reliable insertion of endosseous implants with a length of at least 12 mm. No complications occurred. Biopsies taken from the distraction site revealed formation of lamellar bone parallel to the distraction vector. From this preliminary study it is concluded that the Groningen vertical distraction device has the potential for reliable augmentation of the anterior segment of a severely resorbed edentulous mandible to enable insertion of endosseous implants with adequate length and primary stability.

Aged↗
PubMedDate not supplied

Influence of patient age on the success rate of dental implants supporting an overdenture in an edentulous mandible: a 3-year prospective study.

The aim of this study was to determine the influence of age on peri-implant tissues in patients treated with implant-supported overdentures in the mandible. A prospective study was carried out with 2 groups of healthy edentulous patients. The mean age of the younger group (n = 32) was 46 years (range 35 to 50 years); the mean age of the older group (n = 26) was 68 years (range 60 to 80 years). Two dental implants were placed in the interforaminal region of the mandible, and after a 3-month healing period, overdentures were fabricated. Clinical and radiographic parameters were evaluated immediately after completion of the prosthetic treatment, after 1 year, and after 3 years. The evaluated clinical parameters were implant loss, Plaque Index, Gingival Index, Bleeding Index, and probing depth. Radiographic evaluation was performed using a standardized long-cone technique with a direction device. Statistical analysis was carried out with SPSS software. One implant in the older group was lost during the healing period. After 3 years, the mean scores for Plaque Index, Gingival Index, and Bleeding Index were between 0 and 1 for both groups (out of possible scores of 0 to 3), and the mean probing depth was 3 mm in both groups. The mean bone loss after 3 years was 1.2 mm in the younger group and 0.8 mm in the older group, but this difference was not significant. It was concluded from this study population that the clinical performance of implant-supported overdentures in the mandible is equally successful in younger and older patients.

Adult↗
PubMedDate not supplied

Enhancing osseointegration by capacitively coupled electric field: a pilot study on early occlusal loading in the dog mandible.

Expeditious postoperative appositional growth of bone to dental implants is desired for clinically successful fixation of oral implants. The present study was performed to evaluate the effect of applying a capacitively coupled electric field (CCEF) followed by functional loading on peri-implant osteogenesis in the dog mandible. Nine adult beagles were used in this study. All premolars on both sides of the mandible were removed from each dog. A physio-odontlam implant (POI, Ti-6AI-4v) with 2 stages (3.7 mm in diameter and 8.0 mm in length), whose surface had been treated with anodic oxidation and sandblasted, was placed into each test site by self-tapping. Daily application of CCEF (8 hours per day) was initiated on the day following surgery and continued for 14 days or 21 days. After CCEF treatment was finished for each period, a prosthetic abutment and a straight post were placed on each implant. Four days after placement of the post, implants were placed under functional loading for 30 days. The dogs were then sacrificed, and histologic and radiographic studies of the mandible were performed. Relatively well calcified, mature bone with a lamellar-like structure was observed by contact microradiography and histologic study (double staining with basic fuchsin-methylene blue) of the peri-implant region on the CCEF-treated samples. In contrast, poorly calcified, immature bone without a lamellar structure was observed in control sites not treated with CCEF. The bone area ratios of the CCEF-treated sides were larger than those of control sides. These results suggest that the application of CCEF after implant placement may enhance peri-implant osteogenesis, even with functional loading.

Animals↗
PubMed1999

[The comparison of bone densities of mandible and coxofemoral region between senile people with edentulous jaws and those with dentate jaws].

OBJECTIVE: To observe if the senile people with edentulous jaws had lower bone dentilies of mandible and coxofemoral region than those with dentate jaws, and to find the systemic risk factors which were responsible for the tooth loss and the formation of edentulous jaws. METHODS: Two groups of senile people were selected. One group was edentulous and the other was dentate. All of them were examined by dual energy X-ray absorptiometry(DXA). RESULTS: The senile people with edentulous jaws had significantly lower bone densities of mandible(P < 0.001) and they also had lower bone densities of coxofemoral region than the dentate group people. CONCLUSION: It indicated that the decreased of bone densities of mandible and coxofemoral region was one of the systemic risk factors for tooth loss and the formation of edentulous jaws.

Age Factors↗
PubMed1999

[An experimental study on transplantation of frozen autogenous tooth-mandible compound].

OBJECTIVE: To study the feasibility of reserving the teeth in the transplantation of frozen autogenous mandible. METHODS: Forty adult Wistar rats were used for these operations of transplantation of frozen autogenous tooth-mandible compound (ATMC) and fresh ATMC. Then the healing process after transplantation of frozen ATMC and fresh ATMC was compared by clinical, radiographical, histological and microangiographical observation. RESULTS: There were no significant differences between the healing process of frozen ATMC and that of fresh ATMC, and the fibres of regenerated periodontal membrane which maintained the dental root in normal position could be imbedded in the newly formed cementum. CONCLUSION: It is feasible to transplant the frozen ATMC for reconstructing the mandible and improving its function in clinic.

Alveolar Process↗
PubMed2002

Assessment of density and mandible bone structure in patients with generic osteoporosis symptoms.

In a group of 130 patients with diagnosed osteoporosis and in 110 patients in control group radiovisiographic test of mandible bone structure had been carried out. Digital images analysis was carried out using Software Radiograph Workshop. It proved that in the group of patients with osteoporosis process in comparison with the control group there has been observed a significant deterioration of mandible bone density, defined as reduced bone mineral contents (BMC), reduced bone mineral density (BMC), and reduced mandible bone density (BD). Bone structure analysis showed in the control group of the treated patients with osteoporosis lower than in the control group quantity of structure of trabecular number (STN), deterioration of bone trabecular density expressed in % of area and greater structure of trabecular width than that in healthy patients.

Absorptiometry, Photon↗
PubMedDate not supplied

[The bone structure of the ramus of the mandible].

Osseous structure of the ramus of mandible (RM) is of a practical clinical significance. Osteosynthesis of fractured segments and the success of the sagittal or the horizontal ramus split osteotomy depends on the cortical bone disposition and thickness. After morphometric investigations of the RM, conducted on 70 mandibles of adults, consecutive horizontal and frontal sections were made. On these sections, the cortical layer was studied and the cortical bone thickness was measured at four previously marked points. In the regard of morphometry, the significant datum is that nearly half of all the cases is grouped round the mean value of any parameter. Cortical bone is continuous and its two main sheets are the buccal and the lingual cortical plates. In its entirety, the buccal cortical plate is thicker than the lingual. The thickness of both cortical plates increases in the direction from the coronoid process to the angle of mandible.

Adult↗
PubMed2003

The development of bone mass and bone strength in the mandible of the female rat.

The present study provides baseline data for a number of mandibular growth dimensions, specially on bone mass and bone strength, that were collected between the 21st and the 180th days of postnatal life, which are intended as a reference for researchers designing experimental studies, specially on mandibular catch-up growth, and as an aid for clinicians who must evaluate results from published animal studies for validity and potential extrapolation to the human clinical situation. Fifty weanling female Wistar (Hsd:Wi) rats were fed ad libitum a diet previously shown to allow normal, undeformed mandibular growth. Five of them were randomly selected at different times between 21 and 180 d of life. Mandibular growth was estimated directly on the right hemimandible by taking measurements between anatomical points; mandibular bone mass (calcium mass) was estimated from the mg of calcium, determined by atomic absorption spectrophotometry, present in the ashes of the left hemimandible; and mechanical properties of the right hemimandible were determined using three-point bending mechanical test. Dimensions, bone calcium mass and bone strength of the female rat mandible increased linearly from day 21 to approximately day 90. Bone growth, as expected, was more than twice when assessed from bone weight than when derived from mandibular area, length or height when the parameters were expressed as the relative increase from the mean infant condition. The growth rate of the posterior part of the mandible (behind the third molar) was almost five times greater than that of the anterior part. The rates of growth of the studied parameters showed a marked decline after day 90. ANOVA indicated that no statistical differences were found between day 90 and day 120 values. It could be concluded that the female rat mandible attains its adult size, peak bone calcium mass and bone structural mechanical properties at some point between 90 and 120 d of postnatal life. Because of the extremely high positive correlation between mandibular bone calcium mass and both mandibular area and mandibular weight, it was possible to calculate the mandibular peak bone mass from the relations 7.69 mgCa/cm2 and 0.19 mgCa/mg bone.

Aging↗
PubMed1992

Secular changes within Arctic and Sub-Arctic populations: a study of 632 human mandibles from the Aleutian Islands, Alaska and Greenland.

A series of 632 human mandibles was used to test temporal variations in two Aleut populations and spatial variations in four homogeneous Greenlandic Eskimo populations. Sixteen metric variables and five non-metric observations were applied to generate univariate and multivariate statistics to determine variations caused by group homogeneity (Greenland), sexual dimorphism (Aleutian and Greenland), bilateral asymmetry (Aleutian and Greenland), temporal variation (Aleutians), and spatial variation (Greenland). The following results were obtained: (1) sexual dimorphism outweighed any other investigated variation, (2) no bilateral asymmetry was found in the metric variables, (3) temporal variation (Aleutian) was more significantly expressed in the male group than in the female group (patrilocal residence?), (4) spatial variation (Greenland) was more significantly expressed in the female group (matrilocal residence?), (5) the highest biological distance within the Greenlandic isolates was found between the Northeastern and Southeastern coastal areas, (6) variations in the mandible were related to metric changes rather than to changes in the morphological configuration, and (7) changes in non-metric frequencies (i.e., for mandibular tori as observed on the west coast of Greenland) were primarily induced by phenotypical variation (masticatory stress, changes in diet, ante-mortem loss of premolars and molars) caused by an inceptive increase of exogamic tendencies. The study concludes that as a single bone the human mandible yields a considerable quantity of information applicable to biological variations and reconstructions of biological and social histories, and that this information is conveniently available within the Arctic and Sub-Arctic populations.

Alaska↗
PubMed2004

[Application of image correction in 3D reconstruction of mandible from CT slices].

Precision registration of serial sections is an important step for 3-D image reconstruction. It directly affects the accuracy of the reconstructed result and parameter computation. This problem has been studied and demonstrated by many investigators, but the whole process has not yet reached good performance. In this paper, we discussed the registration of serial sections image of mandible and put forward a method of the soft registration-based transformation on the basis of the hard registration in consideration of the speciality of 3-D image reconstruction for the serial sections of mandible. Employing control points and using Affine Transformation and Extended Hough Transformation, we solved the problem of displacement on 3-D image reconstruction for serial secons and paved the way for reconstructing the mandible microstructure with reality. The results of experiments indicate that the 3D image reconstructed after registration has only a little distortion.

Humans↗
PubMedDate not supplied

Mylohyoid bridging in South Indian mandibles.

The incidence of the bony bridging of the mylohyoid groove of the mandible was studied in a collection of two hundred and twenty five south Indian mandibles. The bony bridging was noticed in 6.39% of the mandibles studied. The incidence of this trait shows a wide range of variation among the different population groups of India. The bony bridging of the mylohyoid may be useful as a non-metric trait in population studies when used in combination of other non-metric traits.

Adult↗
PubMedDate not supplied

The extremely resorbed mandible: a comparative prospective study of 2-year results with 3 treatment strategies.

PURPOSE: The aim of this prospective clinical study was to compare the clinical and radiographic results of 3 modes of implant treatment in combination with an overdenture in patients with extremely resorbed mandibles. The 3 treatment strategies used were a transmandibular implant, augmentation of the mandible with an autologous bone graft followed by placement of 4 endosseous implants, and the placement of 4 endosseous implants only. MATERIALS AND METHODS: Sixty edentulous patients met the inclusion criteria and were assigned according to a balanced allocation method to 1 of the 3 groups. Postoperative complications, implant survival, periodontal indices, change in mandibular bone height, and prosthetic complications were assessed during a 2-year evaluation period. RESULTS: During the evaluation period significantly more implants were lost in the transmandibular implant and the augmentation groups compared to the group with endosseous implants only. Except for the Bleeding Index and the Periotest values, the periodontal parameters did not differ significantly among the groups. In all 3 groups, there was no significant bone loss at most locations. Minimal prosthetic retreatment was necessary. DISCUSSION: Although implant loss is a frequently used outcome measure for success, the necessity of retreatment seems to be of more relevance for both the patient and the clinician. CONCLUSIONS: The results of this study suggested that patients with extremely resorbed mandibles can be treated with implants alone in this patient population.

Alveolar Bone Loss↗
PubMed2004

Treatment effects of chin cup appliance on mandible in Class III malocclusion: strain tensor analysis. A pilot study.

OBJECTIVE: The effects of chin cup therapy on the mandible in Class III malocclusions have been investigated extensively via cephalometric analyses. However, the actual sites of mandibular skeletal change are not detectable with conventional cephalometric analysis. It is important to elucidate the association between remodeling of the mandible with the mechanical stress applied with chin cup therapy. METHOD AND MATERIALS: In this study, the geometric morphometric changes in the mandible from chin cup force and/or growth were investigated using strain tensor analysis. RESULTS: This geometric morphometric analysis reveals that mandibular deformation arises partly due to a size change and partly due to a shape change. The direction and magnitude of principal vectors of the strain tensors may provide more information about this deformation. CONCLUSION: Strain tensor analysis may show the degree of transformation within the mandibular geometric configuration due to treatment effects and/or growth changes as seen on lateral cephalometric radiographs.

Bone Remodeling↗
PubMed2005

[Developing a finite element model of human head with true anatomic structure mandible].

A finite element model of human mandible is developed from CT scan images by the technologies of three-dimensional reconstruction, image processing and meshing. The mandible model is connected to one modified head model of Hybrid III dummy with joint according to the anatomic structure and mechanical characteristics of the temporomandibular joint. Then a finite element model of the human head with the true anatomic structure mandible is developed. This model has been validated with the cadaver test results. It can be used in researches on the mechanism of craniofacial blunt-impact injury and on the assessment of injury severity.

Biomechanical Phenomena↗
PubMedDate not supplied

Intraosseous course of the inferior alveolar (dental) nerve and its relative position in the mandible.

The present study was planned to evaluate the position of the mandibular foramen (MF) and the course of the inferior alveolar nerve in 12 right and 14 left cadaveric hemimandibles. The soft tissue including the muscle attachments of the mandible was cleaned and the inferior neurovascular bundle was dissected up to the MF. The distances from the MF to the angle, symphysis menti, 3rd molar, and the lower point of the mandibular notch were measured. The bone was chiseled from its lingual surface to expose the mandibular canal. The distances from the nerve to the alveolar and inferior borders were measured. The distance from the MF to different landmarks did not show any side differences except the one to the symphysis menti (P<0.05; Mann-Whitney 'U' test). Similarly the distances from the nerve to the borders also did not show any significant side differences. These data indicate that, on average, MF is located at a symmetrical point on the ramus on either side, although, not exactly at a fixed distance from any landmarks tested. Further, the canals were located either at near to the middle or below near to the base of the mandible. This study concludes that, the location of the MF varies from bone to bone despite its bilateral symmetry. Further, the canal and consequently the nerve do not maintain a constant position in the mandible.

Alveolar Process↗
PubMed2005

[Langerhans' cell histiocytosis of the mandible in infant: report of one case].

Langerhans' cell histiocytosis of the mandible is a rare disease in infant. This article reported a case of Langerhans' cell histiocytosis of mandible in a 2-year old female child. The clinical manifestation, radiographic characteristics, pathologic diagnosis, differential diagnosis and treatment were discussed. It is concluded that Langerhans' cell histiocytosis of the mandible in infant is rare without typical clinical manifestation and radiographic characteristics; final diagnosis is based on pathological examination with the characteristic hyperplasia of Langerhans' cell; immunohistochemistry examination of S-100 and CD1a are useful for diagnosis and differential diagnosis. Surgical resection with close postoperative follow-up is suggested as the main treatment for this disease.

Female↗