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Biomedical subjects

M S Block

Publications and source records attributed to M S Block.

At least 37 records · Page 2Linked to original sources
PubMed1996

Radiocephalometric evaluation of a family with mandibulofacial dysostosis.

Persons from four generations of a family with mandibulofacial dysostosis (MFD), known as Treacher Collins (TC) Syndrome, were examined for the presence of clinical signs traditionally associated with this syndrome. In this family, 14 adults, who had been judged trait bearers by an earlier family study were included in this study. Maxillary and mandibular study models were taken of affected and unaffected family members. Panoramic cephalograms and lateral radiographs were taken. The lateral cephalograms were traced and digitized on a computer system and compared. The 117 cephalometric values of the trait bearers were compared with known standard values and nontrait bearing family members. In the trait bearing group, 81 of the 117 values and, in the nontrait bearing group, 72 of the 117 values were significantly different (p < 0.05) when comparing mean values to the accepted normal range. The interfamily comparison between trait-bearing and nontrait members revealed nine values to be significantly different. This indicates that cephalometric analysis of these patients, some of whom have minimal clinical expression of the gene, may have potential value for screening and further characterization of this condition. The results also suggest that intrafamily comparisons may be of greater value for diagnostic confirmation of TC than comparison with literature norms.

Adult↗
PubMed1995

Anterior maxillary advancement using tooth-supported distraction osteogenesis.

PURPOSE: This study used the principle of distraction osteogenesis to advance the anterior maxilla of the dog using a totally tooth-supported distraction device. MATERIALS AND METHODS: After an anterior maxillary osteotomy, the distraction device was activated 0.5 mm every 12 hours to advance the anterior segment 10 mm in 10 days. RESULTS: Serial tooth and radiographic measurements indicated that on the 10th day the average tooth advancement was 8.4 mm +/- 1.5 mm and the average skeletal advancement was 4.0 mm +/- 1.5 mm. After 6 weeks the average tooth advancement was 7.2 +/- 1.6 mm and the average skeletal advancement was 3 +/- 1.3 mm. At 3 months the tooth advancement was 6.2 +/- 1.5 mm and at 6 months the tooth advancement was 5.0 +/- 1.1 mm. Bone healing was present in all animals. CONCLUSION: This results of this study indicate that a tooth-borne maxillary distraction device will result in significantly greater dental movement than skeletal movement and that skeletal fixation may be needed for appliances used to advance the maxilla.

Animals↗
PubMed1995

A new device for absolute anchorage for orthodontics.

A new device has been designed to provide anchorage for orthodontic tooth movement. It is a disk, textured and hydroxylapatite coated on one side, with an internal thread on the other side. It is placed on palatal bone and, after integration, can be connected to teeth for anchorage. This article reviews a dog study demonstrating unilateral tooth movement towards the "onplant" and a monkey study mimicking its use to anchor the molars for anterior retraction.

Alloys↗
PubMed1994

Use of distraction osteogenesis for maxillary advancement: preliminary results.

In this pilot study, the principle of distraction osteogenesis to advance the anterior maxilla of the dog was used. After an anterior maxillary osteotomy, the anterior segment was advanced 10 mm in 10 days. Soft and hard tissue formation resulted in complete healing across the distraction gap without a soft tissue defect.

Animals↗
PubMed1994

Long-term follow-up on hydroxylapatite-coated cylindrical dental implants: a comparison between developmental and recent periods.

PURPOSE: To compare success rates for dental implants placed from 1985 through 1988 and from 1989 through 1991, and to investigate the factors associated with success or failure. PATIENTS AND METHODS: All hydroxylapatite-coated cylindrical implants placed from 1985 through 1991 were followed yearly. Lifetable survival analyses compared implant success for a "developmental period" from 1985 through 1988 (4 to 8 years follow-up) and a "recent period" from 1989 through 1991 (1 to 4 years follow-up). Reasons for success or failure, time from implant placement to removal related to failure reason, outcome after implant removal, and a morbidity analysis are included. RESULTS: The 7 to 8-year cumulative success rate for all implants placed in the developmental period (maxilla and mandible combined) was 86.5%; it was 84.2% for all maxillary implants and 87.5% for all mandibular implants. The cumulative success rate for all implants placed in the recent period was 97.5%; it was 97.5% for all maxillary implants and 97.6% for all mandibular implants. The difference between the two periods was statistically significant only for the anterior maxilla. Regression analysis on the interval success rates indicates that interval failure did not follow a linear relationship with time. The most common reasons associated with failure were lack of keratinized gingiva, poor oral hygiene, mechanical overload, and malposition. CONCLUSION: Comparison with previously reported cumulative success rates indicated learning curve experiences comparable with other implant systems. Improvements in hardware, surgical and prosthetic techniques, and patient selection have led to an improvement in success rates with the recent period implants.

Bone Resorption↗
PubMed1994

Implant reconstruction of a facial trauma patient: clinical report.

Dental implants can be used for the replacement of lost teeth as a result of trauma, even in complex cases with extensive loss of hard and soft tissues. Cooperation between the surgeon and restorative dentist is essential. The sequence of steps each team member must take to reach the definitive prosthesis stage must be clearly defined during treatment planning. A clinical report is presented.

Adolescent↗
PubMed1994

Maxillary sinus bone grafting.

When a patient is missing posterior teeth and desires a fixed prosthesis, bone grafting is often needed. Since 1983, our clinical experience indicates that sinus grafting can provide very good restoration of the posterior quadrants. If the implants are loaded in a physiologically stable manner, one may expect maintenance of bone levels.

Alveolar Bone Loss↗
PubMed1993

Current trends in implant reconstruction.

Significant advances have occurred in preprosthetic surgery in the past decade. Patients whose problems range from the loss of a single tooth to extreme conditions involving acquired or congenital defects now have options for reconstruction previously not possible. Optimal care most often requires a team approach with careful planning and execution. Ongoing basic research and strict clinical documentation involving current and future areas of treatment will provide an even greater degree of safety and effectiveness for our patients.

Bone Transplantation↗
PubMed1993

Changes in the inferior alveolar nerve following mandibular lengthening in the dog using distraction osteogenesis.

Distraction osteogenesis as per Ilizarov was used to lengthen the canine mandible. In this study, physiological and ultrastructural examination of the inferior nerve was performed. Mandibular body corticotomies were performed, and the mandible was distracted 7 mm. The animals were killed 4 weeks after the distraction was completed. Bone formed within the distraction gap in all dogs. There was no statistically significant difference in the jaw-jerk voltage between control and experimental sides. There was a significant difference between the distracted and control nerves in only one area of one nerve.

Animals↗
PubMed1993

Update on the vitek partial and total temporomandibular joint systems.

A retrospective recall study was done on 262 VK I (N = 138) and VK II (N = 124) (Vitek, Inc, Houston, TX) partial and total temporomandibular joints placed between 1982 and 1990. The cumulative success rate of VK I total joints observed for up to 10 years was approximately 20%, whereas the success rate of VK II total joints observed up to 6 years was approximately 80%. At the 5- to 6-year interval for each, these rates were 44% and 79%, respectively. Wear of the Teflon fluorinated ethylene propylene polymer surface was the primary reason for VK I failure; there was no material failure of the VK II prostheses. Slightly better pain relief, increase in interincisal opening, improvement in diet, and greater overall satisfaction were noted with the use of VK II. A highly significant improvement in success data was found if no surgery had been performed before either VK I or VK II total joint placement. Rib grafts were not particularly helpful after removal of total joint prostheses, particularly if the patient had a history of multiple surgeries. Total temporomandibular joint surgery must be reserved for patients in whom alternative surgical methods have failed or are no longer indicated. All total joint implants, particularly the VK I, must be observed closely with clinical examination and imaging and removed at the earliest sign of material failure.

Adult↗
PubMed1993

Maxillary sinus grafting for totally and partially edentulous patients.

The presence of the maxillary sinus and lack of adequate bone to stabilize the implants could make traditional implant placement impossible. The solution includes grafting bone to the posterior maxilla to provide adequate bone support for implant integration and long-term survival.

Bone Transplantation↗
PubMed1993

Long-term results on VK partial and total temporomandibular joint systems.

This article reviews the results obtained on 262 VK partial and total temporomandibular joint (TMJ) procedures followed up to 10 years. VK I total joint (placed 1982 to 1986) cumulative success rate was 44% at 6 years and 20% at 10 years, while VK II (placed 1986 to 1990) cumulative success rate was 80% at 6 years. Material wear of the Teflon FEP surface of the VK I fossa was the most common reason for failure. There were no VK II material failures. A significant improvement in clinical success parameters for both prostheses was found if no previous surgeries were done before VK I or VK II total joint placement. Rib grafts were not helpful after removal of total joint prostheses if patients had a history of multiple procedures. Total TMJ prostheses must be reserved for patients with alternative surgical failures or when these procedures are no longer indicated. Close monitoring by clinical examination and imaging is necessary.

Adolescent↗
PubMed1993

Cylindrical HA-coated implants--8-year observations.

Controversy exists concerning the integrity of hydroxyapatite-coated implants over time. The Louisiana State University Oral and Maxillofacial Surgery Department studied data of 1,374 HA-coated implants that were placed from 1985 to 1991. Data were examined according to life-table survival, interval success rate, reasons for failure, and long-term effects. The rate of integration for HA-coated implants was found to be superior to that of noncoated, titanium implants. The HA-coated implants also showed excellent survival and function rates.

Dental Implants↗
PubMed1992

Tissue-supported implant overdentures.

Overdenture techniques can be modified for use with implants. Generally the implants, which replace the tooth roots, can be placed in a position to permit optimum retention and stability as well as enhancing esthetics. Bony undercuts, which at times are present with the retention of tooth roots, are not a problem when using implants. Various retentive schemes are available to retain the prosthesis and can be matched to the individual needs of patients in regard to retention, stability, and the ability to insert and remove prostheses. Two implants can adequately support an overdenture. The superstructure must be designed to enable the patient to maintain a healthy oral environment. The patient must understand and be able to perform required oral hygiene procedures. The use of overdentures over implants affords the dentist another option in meeting the needs of the patients.

Dental Clasps↗
PubMed1992

Prospective review of integral implants.

There are several factors that strongly correlate to HA-coated implant success and the prevention of implant morbidity. Surgical placement must be performed without compromise in technique. Implants placed into thin ridges or those that had dehiscence of their surface did not uniformly gain bone attachment levels during the healing period. Countersinking implants in extraction sites was critical; labial bone implant defects should be grafted with particulate HA. HA grafts to labial bone defects at the time of implant placement surgery are still short-term. Primary closure of all implant surgical sites prevented epithelial invagination into the surgical site and is associated with improved bone height around implants. Premature exposure of the implant during the healing period is associated with crestal bone loss. Loading forces should be physiologic, with maintenance of a physiologic equilibrium by a balanced restoration. Bone bulk should be created or preserved. Bone around implants may adversely respond to excessive loading forces. In the posterior maxilla, crestal bone loss has been observed that seems to result from excessive cantilever-type forces placed on the implants or from when implants are placed in the posterior mandible developed progressive bone loss that was associated with several factors. These factors included articulation against a natural occlusion, a horizontal ridge contour level with the external oblique ridge, a nonhygienic restoration, and the lack of keratinized gingiva against the abutment. Whether titanium implants develop progressive bone loss in the face of these factors is unknown. The presence of keratinized gingiva strongly correlated to bone maintenance in the posterior mandible. Because of this statistically significant finding, implant exposure should preserve all keratinized gingiva by transposing it labially to the implants. Most patients who receive implants for dental restoration have lost teeth because of caries and periodontal disease. The patient's behavioural patterns need to be redirected to maintain excellent oral hygiene in order to prevent peri-implant gingivitis. A hygienic restoration may be one of the most important factors associated with excellent implant health. Immediately upon receiving their restoration, patients did well maintaining their peri-implant hygiene. However, many patients do not continue their peri-implant hygiene. However, many patients do not continue their new hygiene methods and need to be strongly reminded to maintain their oral hygiene. Some patients do better than others. For some, a porcelain restoration with the restoration subgingival is well tended, but for others 4 to 5 mm of space needs to be established in order to prevent gingival problems.(ABSTRACT TRUNCATED AT 400 WORDS)

Dental Implantation, Endosseous↗
PubMed1991

Placement of endosseous implants into tooth extraction sites.

This study reports 4-year experiences with placement of hydroxylapatite-coated dental implants into extraction sites immediately after tooth extraction. Small defects present after implant placement were treated with dense, nonresorbable hydroxylapatite. Larger defects present after implant placement were treated with demineralized bone. Indications and contraindications for placement, as well as surgical techniques, are discussed.

Bone Resorption↗