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Alveolar ridge augmentation using nonresorbable hydroxylapatite with or without autogenous cancellous bone.

A four-year prospective evaluation of the use of nonresorbable, particulate hydroxylapatite (HA) to augment deficient alveolar ridges was performed. The material was used alone and in combination with finely crushed autogenous cancellous bone. Implants were delivered subperiosteally by syringe injection, usually using local anesthesia for Class I to Class III ridges and general anesthesia for Class III and Class IV ridges. The improved ridge height and width were stable. Postoperative resorption with significant loss of ridge height, frequently seen with rib and iliac crest onlayed grafts, was not observed with HA augmentation. Permanent denture construction began as early as three weeks postoperatively and by four to six weeks if HA was combined with autogenous cancellous bone. It was possible to place mandibular staple implants simultaneously or following HA augmentation. Visor osteotomy techniques were improved by use of HA to produce a wider, more convex stable ridge. Although skin, mucosa, or dermal vestibuloplasties were performed as early as three months postoperatively in a small number of patients, there appeared to be a lesser need for vestibuloplasty after HA augmentation than after onlay bone grafting. In addition, prosthodontists performed fewer denture relines after HA augmentation than after onlay bone grafts. The authors believe the most significant factor accounting for these observations is the firm, nonmobile mucosal base resulting from augmentation with HA. The resultant stable, soft tissue base and improved ridge height and contour have contributed to a comfortable, retentive, stable denture for these patients. The prosthetic and surgical procedures are easier to perform and have produced superior, more permanent results than onlay bone grafts and alloplasts. Preliminary studies also point to exciting possibilities for use of HA as a bone substitute/marrow extender in maxillary and mandibular defects, cysts, and clefts and in osteotomies for orthognathic surgery.

Adult↗

Long-term radiographic evaluation of hydroxylapatite-augmented mandibular alveolar ridges.

From six months to four years after alveolar ridge augmentation was performed, the vertical ridge heights of 74 Class III and Class IV alveolar ridge deficiency patients, who had undergone augmentation with hydroxylapatite with or without autogenous cancellous bone, were measured using panoramic radiographs adjusted for magnification errors. No statistically significant decreases in vertical ridge heights were seen when only hydroxylapatite was used, nor were there significant differences between the two types of hydroxylapatite particles used. Unlike other bone onlay procedures, the use of autogenous bone and HA together did not result in significant decreases in vertical ridge height.

Alveolar Process↗

A technique for osseous restoration of deficient edentulous maxillary ridges.

A technique for maxillary bone grafting to augment the atrophic ridge is presented, and the results from 15 cases followed from three to ten years are briefly described. Loss of postoperative ridge height ranged from 10-20% in this sample. It appears that the tendencies to postoperative resorption that occur when autogenous particulate cancellous bone grafts are employed to restore atrophic mandibles are not operative in the maxilla.

Alveolar Process↗

Ridge augmentation using solid and porous hydroxylapatite particles with and without autogenous bone or plaster.

Edentulous areas of dog jaws were augmented with solid or porous particles of hydroxylapatite (HA) alone, or combined with either finely crushed autogenous bone or plaster of paris. At the end of the experiment (24 weeks), the augmented ridges were firm and stable and covered with healthy mucosa. The ridges augmented with only porous particles of HA demonstrated a greater amount of bone ingrowth compared with the solid, dense particles. The new bone formation occurred in those parts of the implants adjacent to the underlying alveolar bone. The addition of autogenous bone to the HA particles did not enhance bony deposition, and none of the autogenous bone chips survived for 24 weeks. The amount of new bone in the ridges augmented with plaster of paris and HA was similar to the other groups, and the plaster did not interfere with healing. There was evidence of resorption of the underlying cortical bone in many of the specimens.

Alveolar Process↗

Histologic study of tissue response to implanted hydroxylapatite in two patients.

The tissue response to hydroxylapatite implants that had been used to augment deficient mandibular alveolar ridges was examined histologically in samples taken from two patients at five-months and one-year after implantation, respectively. New bone formation in the interparticular spaces was found in both cases. There was no evidence of foreign body response around the subperiosteal implanted particles.

Aged↗

Chemical, physical, and histologic studies on four commercial apatites used for alveolar ridge augmentation.

The purpose of this study was to evaluate four commercial apatite products. Subperiosteal alveolar ridge augmentation was performed on the maxilla of rats by implantation of granules of two dense products and of two porous products, and the tissue response was compared with the material characteristics obtained by chemical analysis and infrared spectrometry. None of the apatites caused osteoinduction or osteoconduction; fibrous encapsulation with multinuclear giant cells was observed around all four types. One of the apatites was fluorapatite and not hydroxylapatite, as claimed by the manufacturer. The tissue response to this implant material was dominated by multinuclear giant cells.

Alveolar Process↗

The effect of therapeutic radiation on canine alveolar ridges augmented with hydroxylapatite.

The purpose of this investigation was to evaluate the effect of radiation on hydroxylapatite (HA) implanted subperiosteally for alveolar ridge augmentation in dogs. All bicuspids and molars were extracted from 16 dogs. After 6 weeks, nonporous HA granules were implanted subperiosteally on the alveolar ridge. Following 4 months of healing, 12 dogs (experimental group) underwent therapeutic radiation therapy (Co60, 4,000 rad [40 Gy]) to the head and neck region. Four dogs were not irradiated and served as controls. Four animals (three experimental and one control) were killed at 5,6,7, and 8 months after HA augmentation. Light microscopic evaluation showed that approximately 25% of HA granules were encased by bone while the others were surrounded by fibrous connective tissue. Dissolution of the HA was observed. Microparticles of HA were phagocytized as part of a granulomatous inflammatory reaction. This reaction decreased significantly as time elapsed after implantation. Osteoclastic activity was seen at the junction of HA and periosteum and as part of bone remodeling. Dissolution of the HA granules and the granulomatous inflammatory reaction were not significantly increased by therapeutic radiation. The radiation did not cause development of dehiscence or osteonecrosis.

Alveolar Process↗

Correlations between lower incisor crowding and lower incisor position and lateral craniofacial morphology.

Crowding of the lower incisors is a problem encountered frequently in orthodontic practice. Successful therapy may depend on the orthodontist's ability to evaluate factors contributing to the overall pattern. Two of these factors, vertical skeletal morphology and lower incisor position in the lateral cephalogram, were evaluated. Dental casts and cephalograms of 100 children with primary mandibular incisor crowding (that is, primary discrepancy between mesiodistal tooth width and available space of the dental alveolar process and apical base) were examined in this study. Results indicated the following: (1) all vertical skeletal and lower incisor position measurements closely duplicated published norms, (2) no correlation was found between lower incisor crowding and either skeletal morphology or lower incisor position, (3) a factor analysis did demonstrate, however, that other selected variables were interrelated, and (4) the cause of lower incisor crowding must be attributed to factors not examined in this study.

Cephalometry↗

Second respiratory and upper digestive tract cancer following oral squamous cell carcinoma.

727 patients with squamous cell carcinoma (SCC) of the lip and oral cavity have been followed for the occurrence of second primary tumours (SPTs) in the respiratory and upper digestive tract (RUDT). 74 patients (10%) developed at least one SPT in the RUDT. The incidence of SPTs was expressed per 1000 person-years of follow-up. In our study about 28 SPTs per 1000 person-years of follow-up were seen in the RUDT. Patients were at risk for a second primary tumour, at a steady rate of approximately 2.8% per year during at least 10 years. Furthermore, patients with an index tumour in the lower part of the mouth (floor of mouth, retromolar area and lower alveolar process), which is more related to tobacco and/or alcohol, seem to be more at risk for SPTs than patients with an index tumour in the other (sub)sites of the mouth.

Aged↗

Influence of orthodontic derotation and extrusion on pulpal and periodontal condition of autotransplanted immature third molars.

The aim of this study was to determine the influence of orthodontic treatment on the pulpal and periodontal condition of 91 transplanted immature third molars. In patients with atrophy of the alveolar process or unfavorable root morphology, transplants had to be placed in extreme rotated or infraoccluded positions. After 3 to 6 months, these transplants were derotated (45 degrees to 90 degrees) to a correct position in the dental arch (derotation group; n = 28) or extruded to the occlusal plane (extrusion group; n = 21). Finally, approximal spaces were closed in both groups. A sample of 42 transplanted third molars with no orthodontic treatment need served as the control group. All transplants were followed clinically and radiologically for a mean period of 4.0 years. With respect to pulpal and periodontal conditions, no significant differences were observed between the control and the extrusion group. In contrast, compared with the control group, transplants in the derotation group had a significantly poorer pulpal and periodontal condition. In the derotated transplants, a significant correlation was detected between pulp necrosis and orthodontic treatment of multi-rooted transplants. This study indicates that orthodontic extrusion and minor lateral movements of autotransplanted immature third molars, as well as rotation of single-rooted third-molar transplants, represent no additional risk to transplant survival. In contrast, rotation of multi-rooted transplants seems to initiate later severance of the vascular and nerval supply to the pulp.

Adolescent↗

Maxillofacial fractures in Hamedan province, Iran: a retrospective study (1987-2001).

BACKGROUND: This study presents the various types, causes and incidence, along with their clinical management and associated complications of maxillofacial fractures at an emergency hospital in Hamedan, Iran. PATIENTS AND METHODS: A total of 2268 patients with 3107 facial fractures treated between 1987 and 2001, were retrospectively analysed. The average number of fractures for each patient was 1.37. Data on the patient's age, gender, cause, site, treatment modalities and trauma-associated complications were recorded and assessed. RESULTS: Men 21-30 years of age sustained the most facial fractures. The ratio of male to female was 3.8:1. The age range was 4 months to 90 years (mean 24.6 years). Most fractures were caused by motor vehicle accidents (60%, 1360 pts), followed by falls (18.9%, 429 pts), and assaults (10%, 227 pts). Isolated mandibular fractures (52.6%, 1194 pts) were most common, followed by isolated mid-facial fractures (29.5%, 669 pts) and alveolar process fractures (15.1%, 342 pts). 70.8% of patients were treated by closed reduction, 17.8% with open procedures and 11.4% using both. Complications resulting directly from trauma occurred in 5.5% of patients. CONCLUSION: The findings support the view that both the causes and incidence of maxillofacial fractures vary from one country to another.

Accidental Falls↗