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At least 595 records · Page 33Linked to original sources
PubMed2003

"All-on-Four" immediate-function concept with Brånemark System implants for completely edentulous mandibles: a retrospective clinical study.

BACKGROUND: Immediate-function Brånemark System implants (Nobel Biocare AB, Gothenburg, Sweden) have become an accepted alternative for fixed restorations in edentulous mandibles, based on documented high success rates. Continuous development is ongoing to find simple protocols for their use. PURPOSE: The purpose of this study was to develop and document a simple, safe, and effective surgical and prosthetic protocol for immediate function (within 2 hours) of four Brånemark System implants supporting fixed prostheses in completely edentulous mandibles: the "All-on-Four" concept. MATERIALS AND METHODS: This retrospective clinical study included 44 patients with 176 immediately loaded implants, placed in the anterior region, supporting fixed complete-arch mandibular prostheses in acrylic. In addition to the immediately loaded implants, 24 of the 44 patients had 62 rescue implants not incorporated in the provisional prostheses but incorporated in final prostheses later on. RESULTS: Five immediately loaded implants were lost in five patients before the 6-month follow-up, giving cumulative survival rates of 96.7 and 98.2% for development and routine groups, respectively. The prostheses' survival was 100%, and the average bone resorption was low. CONCLUSIONS: The high cumulative implant and prostheses survival rates indicate that the "All-on-Four" immediate-function concept with Brånemark System implants used in completely edentulous mandibles is a viable concept.

Acrylic Resins↗
PubMed2003

Immediate loading of Brånemark System TiUnite and machined-surface implants in the posterior mandible: a randomized open-ended clinical trial.

BACKGROUND: Immediate loading of osseointegrating implants shortens the treatment time and makes it possible to give the patient an esthetic appearance during the whole treatment period. A previous retrospective clinical study showed a success rate of 94.2% after 1 year of immediate loading of fixed partial constructions in the maxilla supported by machined-surface implants. The recently introduced Brånemark System TiUnite (Nobel Biocare AB, Gothenburg, Sweden) surface has been shown to better maintain primary implant stability and to help achieve secondary stability earlier compared with the machined surface. PURPOSE: The aim of the present study was to compare TiUnite and machined-surfaced Brånemark System implants when applying immediate loading of partial fixed bridges in the posterior mandible. MATERIALS AND METHODS: Forty-four patients were randomized for test and control therapy. In the test group, 22 patients received 66 Brånemark System TiUnite surface implants supporting 24 fixed partial bridges, all of which were connected on the day of implant insertion. In the control group, 22 patients received 55 Brånemark System machined-surface implants supporting 22 fixed partial bridges, which also were connected on the day of implant insertion. All constructions were two- to four-unit bridges. Bone quality and quantity were assessed. Radiographic examinations were performed on the day of surgery/loading and at the 1-year follow-up visit. RESULTS: Three TiUnite and eight machined-surface implants failed during the first 7 weeks of loading. This resulted in a cumulative success rate of 95.5% for TiUnite surface implants after 1 year of prosthetic load in the posterior mandible. The corresponding cumulative success rate for machined-surface implants was 85.5%. When using the machined-surface implants, the number of failed implants was significantly higher in smokers and in bone quality 4 sites. Such findings were not seen with the use of TiUnite implants, despite the fact that there were more smokers and more implants placed in bone quality 4 in this group. The marginal bone resorption after 1 year of loading was on average 0.9 mm (SD 0.7 mm) with the TiUnite implants and 1.0 mm (SD 0.9 mm) with the machined implants. CONCLUSIONS: The present study demonstrated a 10% higher success rate following immediate loading of partial fixed bridges in the posterior mandible supported by TiUnite surface implants compared with success with machined implants. When using the machined implants, the number of failed implants was significantly higher in smokers and in bone quality 4 sites. Such findings were not seen following the use of TiUnite implants.

Adult↗
PubMed2004

Interimplant distance and crestal bone resorption: a histologic study in the canine mandible.

BACKGROUND: Crestal bone loss has been shown to occur around dental implants. This crestal bone resorption may determine a more apical position of the gingival margin. A clear trend of increased bone loss with increased interimplant distance has been reported. PURPOSE: The aim of the present study was to evaluate, in the canine mandible, the crestal bone behavior around dental implants inserted with different interimplant distances. MATERIALS AND METHODS: Sandblasted and acid-etched implants (Bone System, Milano, Italy) were placed in the mandibles of six beagle dogs. Each dog received 10 implants in the mandible (five in the right side and five in the left side). A total of 60 implants was used in this study. The implants were divided in four groups: group I, with a 2 mm interimplant distance; group II, with a 3 mm interimplant distance; group III, with a 4 mm interimplant distance; and group IV, with a 5 mm interimplant distance. The dogs were killed after 12 months. RESULTS: No statistically significant differences were found in regard to vertical bone loss whereas on the contrary, statistically significant differences were found in regard to lateral bone loss (p = .0001). Statistically significant differences also were found in regard to vertical crestal bone loss (p = .0001). In fact vertical crestal bone loss decreased, from 1.98 mm in group I to 0.23 mm in group IV. CONCLUSIONS: The clinical significance of these data lies in the fact that the increased crestal bone loss results in an increase in the distance between the base of the contact points of the neighboring implants and the crest of bone, and this fact could determine whether the papilla is present or absent between two implants.

Alveolar Bone Loss↗
PubMed2005

Three-dimensional modelling and finite element analysis of the human mandible during clenching.

BACKGROUND: Until recently, very few papers have been published concerning the development, analysis and experimental verification of three-dimensional, finite element modelling of the human adult edentulous mandible. The purpose of this study was to improve the method of modelling by using computer-aided engineering (CAE) and computer-aided design (CAD) methods and to utilize the model in analyzing maxillofacial problems. METHODS: The model geometry was derived from position measurements taken from 28 diamond blade cut cross-sections of an average size human adult edentulous mandible and generated using a special sequencing method. Data on anatomical, structural, functional aspects and material properties were obtained from measurements and published data. The materials were idealized as transversely isotropic. The complete model consisted of 258 solid elements and 1635 nodes. RESULTS: The model was solved for displacements and stresses during clenching. In general, the observed displacement and stresses (tensile and compressive) were highest around the condylar region. Compressive stress was also observed around the premolar and molar bite points. CONCLUSION: This investigation has shown that the use of computer-aided modelling in conjunction with the finite element analysis could be effectively utilized in biomechanical analysis of the mandible. It could help to investigate many functional problems and could reduce the time of extensive experimentations.

Adult↗
PubMed1998

Mandibular stability after sagittal split ramus osteotomy without post-operative maxillomandibular fixation in the treatment of prognathic patients with symmetric mandibles.

This study was designed to examine post-operative stability in prognathic patients with symmetric lower jaws who underwent sagittal split ramus osteotomy (SSRO) of the mandible without post-operative maxillomandibular fixation (MMF). Twenty prognathic patients with symmetric mandibles were investigated. An appliance for repositioning the proximal segment and titanium screw fixation was applied in all patients. Ten patients underwent post-operative MMF with stainless steel wire (mean duration, 9.6 days) and intermaxillary rubber traction after removal of the MMF (Group I), and the remaining ten underwent intermaxillary rubber traction only (Group II) post-operatively. Cephalograms were obtained 2-3 days post-operatively, and 3, 6, and 12 months after surgery. Changes in the positions of upper incisors (U-1), lower incisors (L-1), B-point, and pogonion were examined on lateral cephalograms. In the early stages of follow-up, decreases in the overbite tended to be more marked in Group I than in Group II, and the forward movement of each standard point was significantly larger in Group I than in Group II. No significant differences, however, were revealed between the two groups at 12 months after surgery. Forward movement of anterior cephalometric landmarks, post-operatively, in Group II were significant, however, this pattern differed from Group I, in which big changes occurred in the early stages after surgery. Although the patterns of post-operative changes in the two groups are different, there are no significant differences in their post-operative stability in long-term follow-up. Therefore, post-operative MMF may be avoided when prognathic patients with symmetric mandibles undergo SSRO with an appliance for repositioning the proximal segment and titanium screw fixation.

Adult↗
PubMed2001

Morphogenesis of the medial region of the developing mandible is regulated by multiple signaling pathways.

Experimental evidence indicates that the mandibular primordia are specified as at least two independent functional regions: two large lateral (proximal) regions where morphogenesis is dependent on FGF-8 signaling, and a small medial region where morphogenesis is independent of FGF-8 and dependent on other signals. The patterns of expression of multiple signaling molecules and regulatory genes in the epithelium and mesenchyme of the medial region suggest that the regulatory hierarchies controlling morphogenesis of the medial region of the developing mandible are complex and involve multiple pathways. Recent genetic studies indicate that the 'ET-1-dHAND-Msx1 pathway' constitutes one of the genetic pathways involved in outgrowth and morphogenesis of the medial region. Functional studies in chick mandible suggest that FGFs (other then FGF-8) and BMPs are also part of signaling pathways that regulate morphogenesis of the medial region. These studies suggest that in the medial region of the developing mandible, FGF-mediated signaling is involved in growth-promoting interaction, whereas BMP-mediated signaling is involved in chondrogenesis.

Animals↗
PubMed1990

A comparison of the position of the mental foramen in Chinese and British mandibles.

The antero-posterior position of the mental foramen was studied in 68 Chinese and 44 British skulls of known or calculated age at death. All skulls showed low pre-mortem tooth loss and had a good occlusion. The position of the foramen was related to the body of the mandible as well as to the standing mandibular teeth using two previously published methods. There was no significant difference in the size of the Chinese and British mandibles. There was a significant difference between the two groups when measurements relating the foramen to the body of the mandible (symphysis menti) were considered, the foraminal position being more distal in the Chinese group. The modal position of the foramen in the Chinese sample was along the long axis of the second premolar, whereas in the British sample it lay between the apices of the first and second premolar. The foraminal position apparently moved distally in both groups with age and this was likely to be associated with mesial tooth drift and age-related attrition.

Adolescent↗
PubMed1992

The mandible--an analysis.

In this study, an attempt has been made to examine and analyse the ancient mandibles of people who have died several hundreds of years ago during the second and first millenium B.C. These mandibles have been recovered from the burial mounds in Bahrain (Arabian Gulf) and preserved in the National Museum and the Department of Antiquities in Bahrain. The dental conditions recorded are e.g. attrition, caries, fluorosis, periodontitis or antemortem tooth loss. The results indicate the age, sex, diet, occupation and environmental conditions that existed and even the culture of the people. A comparative study of the ancient mandibles and those of the present generation has been carried out.

Adult↗
PubMed1979

Mandible height and syllable-final tenseness.

Mandible movements in the vowel-to-consonant transition manifest consistent differences between /t/ and /d/ in syllable final position. Both mandible position at its peak value near the articulatory release of the stop and velocity of its ascending movement in the transition are found to be apparently relevant to the tense/lax distinction, even though the reliability of these criteria for categorizing t/d data somewhat varies depending on the speaker. Some related characteristics of lingual movements and similar mandible characteristics for the k/g distinction are mentioned. The data were obtained by the computer-controlled X-ray microbeam system in cooperation with the University of Tokyo group.

Humans↗
PubMed1977

Stress trajectories within the mandible under occlusal loads.

A human mandible was duplicated in birefringent resin. The distribution and effect of occlusal forces within the mandible was demonstrated utilizing birefringent resin models compared to natural specimens. The results of this study reinforce those theories that assign function a major role in bone remodeling in the mandible. Further, the condyle is seen to be a stress-bearing structure.

Birefringence↗
PubMed1979

Relationship between structure and the stress pattern in the human mandible.

The internal bony structure of ten dentate human mandibles was examined on lateral radiograms, and the condylar shape measured with a digital electronic machine. The external surface was coated with photoelastic material. Each mandible was then placed in centric occlusion with brass replicas of the upper arch and the glenoid fossae and set in a supporting frame. Occlusal loads were simulated and the isoclinics recorded in plane-polarized light. The isostatic flow lines were constructed for each mandible. A relation was found between the mandibular structure and the distribution pattern of these lines.

Adult↗
PubMed1981

Facial bone scintigraphy. VII. Diagnosis of malignant lesions in the mandible.

Fifty-four patients were examined clinically, radiographically and scintigraphically with respect to mandible bone involvement by oral carcinoma. Sixteen resected mandibular specimens were available for microscopic examination and the results were correlated to the clinical, scintigraphic and radiographic results. Clinical assessment overestimated and radiography underestimated oral carcinoma involvement of the mandible; scintigraphy was more accurate than was clinical assessment or radiography. Combination of clinical examination with both conventional radiography and bone scintigraphy is recommended for optimum diagnosis of mandible bone involvement by oral carcinoma.

Adult↗
PubMed2001

Mandible and mandibular first molar tooth measurements in dogs: relationship of radiographic height to body weight.

Height measurements of the mandible and the mandibular first molar tooth were obtained from 234 dogs. Statistical analysis was performed to determine possible associations between these measurements and body weight, sex, age, and body condition. There was a statistically significant association between the mandible: mandibular first molar tooth height measurement ratio and body weight (p < 0.0001) in all body weight groups. Small dogs had proportionally larger mandibular first molar teeth relative to mandibular height compared with larger dogs. This relationship may contribute to an increased susceptibility in small dogs for periodontitis and subsequent tooth loss. There was no statistically significant association between the mandible: mandibular first molar tooth height measurement ratio and other parameters evaluated in this study.

Animals↗
PubMed1989

Standard forms of dentition and mandible for applications in rotational panoramic radiography.

Mathematical expressions describing the average form and size of the dentition and the mandible are presented. These expressions should be of value in applications of panoramic radiography when reference to an average standard jaw form is of interest. Data were collected from axial radiographs of 35 males and 35 females of three ethnic groups: Mexican-Americans, black Americans and American and Scandinavian Caucasians. Curves were traced on the axial radiographs representing the dentition and the mandible and points along these curves digitized. Mathematical expressions were established using advanced algorithms for orthogonal polynomial curve fitting, i.e. perpendicular distances to the curved dentition and mandible were minimized rather than distances parallel to the y-axis in an arbitrarily chosen coordinate system. The standard deviations around the polynomials defining the average curves are demonstrated and expressions for calculating the continuously varying standard deviations are given.

Dentition↗
PubMed1994

Cephalometric changes after gradual lengthening of the mandible: an experimental study in sheep.

Gradual distraction after osteotomy has been used both clinically and experimentally to lengthen the mandible. In this experimental study in sheep, the changes in dimensions after osteotomy and gradual distraction were analysed by means of cephalometry. There was a strong correlation between the amount and duration of distraction and the increase in length of the mandible. The difference in length between the operated and control sides persisted for up to 1 year. It was concluded that new bone was deposited and that the increase in length of the mandible was real and permanent.

Animals↗
PubMed2003

Image processing and analysis program for measurement of bone density changes in reference and follow-up standardized extraoral oblique lateral cephalometric radiographs of the mandible.

OBJECTIVES: The aim of this study was to develop an image processing and analysis program for peri-implant bone density measurements of the mandible using extraoral radiographs, which includes a correction for the variable projection of the soft tissues of the face. METHODS: The measurement procedure is based on pairs of reference and follow-up extraoral oblique lateral cephalometric radiographs (OLCRs) of patients with endosseous implants in the anterior part of the atrophic edentulous mandible. The procedure consists of image acquisition, correction for radiographic variation using an aluminium wedge (i.e. film exposure and development) and transformation of the grey values into aluminium-equivalent values. After correction for variation in the projection of the soft tissues of the face using internal calibration fields, the actual peri-implant bone density measurements are performed. RESULTS: The soft tissue projection correction significantly reduces the variation between radiographs owing to the position of the soft tissues. CONCLUSIONS: It is concluded that the described image processing and analysis program, in combination with extraorally made OLCRs, is a valuable technique for measurement of peri-implant bone density changes of the mandible. With minor adaptations, the program can be used for other semi-edentulous patients.

Absorptiometry, Photon↗
PubMed1983

Reconstruction of the mandible.

Forty-five patients were evaluated for reconstruction of the mandible. Thirty-four patients had a particulate cancellous bone and marrow (PCM) crib graft placed. Thirty of 34 were successful at the primary operation producing a success rate of 88%. By using secondary procedures all 33 patients repaired to date have been rehabilitated. A dynamic bendable defect bridging plate with cancellous cortical graft (DBDB plate with CCG) was used in 7 patients, 4 of whom had tumor surgery and 3 of whom were operated on after trauma to the anterior mandible. All 7 cases were successfully rehabilitated in achieving a stable, functioning mandibular arch. An osteomyocutaneous flap was planned to reconstruct the anterior mandible in 4 cases; 1 in this group was not reconstructed. The PCM graft has been our first line approach to the mandibular non-union but with experience we are beginning to rely on the DBDB plate with CCG for large bony defects after both trauma and secondarily after tumor surgery. When indicated, the osteomyocutaneous flap has been eminently successful in restoring function and form in the tumor patient.

Bone Transplantation↗
PubMed1986

Latissimus dorsi myocutaneous-iliac bone flap for reconstruction of massive defects of mandible and oral basis.

Recent advances in reconstructive surgery for head and neck cancer have improved the cure rate of advanced carcinoma, and the function of the organ. However, it still remains difficult to repair the mandible and oral floor. We devised a combined flap of myocutaneous latissimus dorsi and iliac bone, and applied it to two patients with advanced carcinoma of the oral cavity that invaded to the mandible (T4N3M0). Each patient received preoperative irradiation, totalling 30 Gy and 40 Gy. Two weeks before the extensive resection, a sufficient bony mass for the presumed mandibular defect was taken from the iliac crest and transplanted beneath the latissimus dorsi muscle. Defects of the mandible and oral floor were reconstructed using this combined flap immediately after the resection. The patients began to eat 2 weeks after surgery.

Carcinoma, Squamous Cell↗