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Biomedical subjects

R A Voorsmit

Publications and source records attributed to R A Voorsmit.

15 recordsLinked to original sources
PubMed1998

Treatment of the edentulous mandible with a vestibuloplasty combined with Intramobil Zylinder implants: a 5-year follow-up.

The long-term success of endosseous implants is related to healthy peri-implant tissues. Attached keratinized mucosa does not seem important for the prevention of soft tissue complications. Prevention of muscle attachment near the implants, however, seems more decisive for maintaining a favourable peri-implant environment. We treated 150 patients from 1990-91 with two Intramobil Zylinder implants and modified vestibuloplasty, 65 of whom were randomly selected for evaluation at 1 year; 48 of the 65 were also seen at 5 years. The vestibuloplasty was done by the technique of Pichler and Trauner, to prevent muscle pull and to create a thin layer of mucosa around the implants, and endosseous osseointegrated implants were inserted. The results show an adequately depended vestibulum with no muscle pull around the implants and significantly lower pocket depth after 5 years of follow-up compared with similar studies.

Chi-Square Distribution↗
PubMed1998

Randomized prospective clinical trial of two implant systems for overdenture treatment: a comparison of the 2-year and 5-year results using the clinical implant performance scale.

In a prospective randomized clinical trial, edentulous patients were treated with dental implants and overdentures. The results of treatment with two IMZ implants connected by a Dolderbar, and a transmandibular implant (TMI) were compared. By using the clinical implant performance scale, the clinical and radiographic data were evaluated and compared after a two-year and five-year follow up. After the five-year follow up, significantly less problems and complications were recorded in the IMZ group than in the TMI group (Wilcoxon, P=0.03). When compared to the two-year follow up, there was, however, a gradual increase of scores on the clinical implant performance scale in the IMZ group, while in the TMI group only a slight increase was recorded.

Adult↗
PubMed1998

Open bite deformity in amelogenesis imperfecta. Part 1: An analysis of contributory factors and implications for treatment.

Anterior open bite (AOB) is often seen in patients with amelogenesis imperfecta (AI). The skeletal and dental components were analysed in 15 patients with AI and AOB. Measurements on cephalometric radiographs and dental models were compared with those of 130 patients with AOB but without enamel anomalies. Skeletal components in the AI and non-AI group were comparable. The AI group showed omega-shaped dental arches and a reversed mandibular curve of Spee. Orthodontic treatment options are limited because of the conical form of the teeth, tight contacts in the posterior regions and the condition of enamel resulting in difficulties in bonding brackets. Fixation problems encountered during surgery are discussed. A multidisciplinary treatment is outlined consisting of a multi-segment Le Fort I osteotomy followed by prosthetic rehabilitation to stabilize occlusion for at least one year postoperatively.

Adolescent↗
PubMed1998

Open bite deformity in amelogenesis imperfecta. Part 2: Le Fort I osteotomies and treatment results.

Functional conditions, skeletal and dento-alveolar stability and condylar changes in 15 patients with mandibular hypoplasia, anterior open bite (AOB) and amelogenesis imperfecta (AI), who had undergone a Le Fort I osteotomy, were analysed after a mean follow-up of 5 years. Two patients underwent a one-piece Le Fort I intrusion osteotomy and 13 patients a multi-segment Le Fort I osteotomy. In three of these patients, an additional bilateral sagittal split osteotomy was performed. Thirteen patients underwent a genioplasty. Surgery was followed by prosthetic rehabilitation in 10 patients. Skeletal and dento-alveolar stability were analysed on lateral cephalometric radiographs and condylar changes on orthopantomographic radiographs. Transverse stability of the dental arches was analysed on dental casts. The treatment results in this group were compared with patients with similar skeletal features but without amelogenesis imperfecta. The harmony of the long faces was restored and a reasonable vertical stability of the maxilla was achieved, however, a slight open bite and tongue interposition was still present. The transverse stability of dental arches (60%) was disappointing. Rigid internal fixation produced better transverse stability. Progressive condylar resorption was seen in two patients (13%). Less occlusal stability could be achieved in patients with AI, but resulted neither in less skeletal stability nor in more susceptibility to morphological condylar changes.

Adolescent↗
PubMed1997

Bone level changes in patients with transmandibular implants.

PURPOSE: In this article, the mandibular bone height in edentulous patients previously treated with a transmandibular implant was evaluated after the dentures were modified according to the latest prosthetic protocol. PATIENTS AND METHODS: The bone height of 36 patients was measured on three radiographs; the first at the time of insertion of the implant, the second just before using the latest prosthetic protocol, and the third 1 year later. RESULTS: A slight bone increase at the lateral posts and at the cortical screws mesial to these posts was measured. No significant bone increase was found above the lateral cortical screw. CONCLUSION: The bone increase that is found in this study was not of the extent indicated in earlier reports.

Adult↗
PubMed1997

Improvement in oral function following tumour surgery by a combination of tongue plasty by the Steinhäuser technique and osseointegrated implants.

Oral functions such as speaking, chewing and swallowing are often reduced after ablative tumour surgery in the mouth and oropharynx. For restoration of at least a part of these functions, stable dentures and satisfactory mobility of the tongue are necessary. Dental implants can be used to achieve stable dentures. Pre-implant surgery, however, is often needed to reduce the amount of bulky tissue when myocutaneous flaps have been used for reconstruction, and to achieve adequate mobility of the tongue. A combination of tongueplasty by the Steinhäuser technique and osseointegrated implants will be described and discussed. Twelve patients have been treated by this technique between 1992 and 1995, with a mean follow up of 11.6 months. All patients reported an improved tongue mobility and ability to chew. Tongueplasty by the Steinhäuser technique with secondary epithelialization, in combination with osseointegrated implants, is a simple and effective means of improving oral function.

Deglutition↗
PubMed1996

Transmandibular implant versus intramobile cylinder implants: a randomized, prospective clinical trial.

A randomized, controlled clinical trial was conducted to compare two different implant treatment modalities for edentulous patients with severely resorbed mandibles. In one modality (the IMZ group), two intramobile cylinder implants were placed, connected by a Dolder bar and provided with an overdenture, and in the other (the TMI group), a transmandibular implant with a triple bar and cantilever extensions was placed, likewise provided with an overdenture. The conditions of the overdentures, the peri-implant tissues, and the implants were evaluated. Orthopantomograms were taken for radiologic evaluation. An overall complication scale which took account of all aspects was devised to compare the results. The follow-up period was 2-4 years, with a mean follow-up of 3 years. The condition of dentures and oral hygiene aspects were comparable for both groups. The complication rate in the TMI group was significantly higher than that in the IMZ group. The scores on the complication scale resulted in a significant difference between the TMI and the IMZ groups (Wilcoxon, P = 0.0044).

Alveolar Bone Loss↗
PubMed1996

Occlusal and functional conditions after surgical correction of anterior open bite deformities.

The dental occlusion and alterations in orofacial muscles were studied in 267 patients whose severe anterior open bite had been treated with a Le Fort 1 intrusion osteotomy with or without an advancement sagittal split osteotomy about 6 years ago. Only 17% of those patients showed anterior contact, and 20% had no vertical overlap of mandibular and maxillary central incisors at all. Tongue position, activity of masticatory muscles, lip competence, lip-incisor relationship, and breathing mode were assessed. Statistically significant correlations were found between tongue positions and occlusion in both the anterior and the posterior regions. In addition, the activity of the masticatory muscles, habitual mouth posture, and interlabial distance were each significantly correlated to overbite, open bite, and overjet. The interlabial distance was also significantly correlated with both breathing mode and mentalis muscle activity. The activity of the masticatory muscles was negatively correlated with tongue position.

Adaptation, Physiological↗
PubMed1993

Timing and transplant materials for closure of alveolar clefts. A clinical comparison of 296 cases.

A retrospective study of bone grafting of 296 clefts (165 unilateral and 131 bilateral was required) to answer questions about the most favourable timing and the most appropriate bone graft material. The results as such are not exceptional in comparison with earlier publications by the same or other authors, but it is of special interest that operations with different graft materials applied at different times in development, in (usually) a sufficient number of cases, can be compared together. The patients have been operated on during a period of 11 years, by the same surgeons, applying the same principles and techniques. It is shown that early secondary grafting, before the eruption of the canine, results in by far, the highest success rate. Similarly, chin bone is considerably better than any other type of transplant. Aspects of general planning, timing, technique and failures are extensively discussed. Besides the afore-mentioned most significant findings, it is also concluded that the results of grafting during osteotomies are better than they appear; that tertiary grafting is extremely difficult, and requires special surgical skill; that rib grafts score as high as iliac crest grafts and that materials other than these three types of bone should be avoided.

Alveolar Process↗
PubMed1991

The perinuclear factor, a rheumatoid arthritis-specific autoantigen, is not present in keratohyalin granules of cultured buccal mucosa cells.

Rheumatoid arthritis patients have antibodies in their serum directed against the perinuclear factor, a protein component present in keratohyalin granules in the cytoplasm of human buccal mucosa cells. The anti-perinuclear factor (APF) can only be detected by an indirect immunofluorescence test performed on fresh buccal mucosa cells from 'selected donors'. To obtain a more reliable antigen source and to gain more insight into the origin and nature of the perinuclear factor we attempted to culture perinuclear factor-containing buccal mucosa cells. Here we describe the successful culturing of such cells, which, however, did not contain keratohyalin granules nor the perinuclear factor. By adding the phorbol ester 12-o-tetradecanoylphorbol-13-acetate (TPA) we were able to induce keratohyalin granules in both cultured primary buccal mucosa cells and a squamous carcinoma cell line of the cheek (SqCC/Y1). These induced keratohyalin granules do contain the protein profilaggrin, which in vivo, in fresh buccal mucosa cells, co-localizes with the perinuclear factor. However, we were not able to demonstrate the presence of the perinuclear factor, not even after induction of terminal differentiation of the cultured cells nor after Epstein-Barr virus infection. Our results suggest that the perinuclear factor, in contrast to profilaggrin, is not an integral component of buccal mucosa cells.

Antibodies, Antinuclear↗
PubMed1984

Sialocystadenoma papilliferum of the palate.

The clinical and histological data concerning a case of sial -( ocyst )-adenoma papilliferum of the palate are presented. Ten cases of sialadenoma papilliferum have been reported to date. The lesion is characterized by several distinct clinical and histological features resembling in many aspects the syringocystadenoma papilliferum of the skin. Because of the invariable presence of more or less cystically dilated salivary gland ducts we propose to denote the lesion as sialocyst -adenoma papilliferum. Generally these neoplasms behave as benign tumours with an indolent and asymptomatic clinical course, although a single case of a malignant counterpart has been reported. An adequate local excision seems to be the treatment of choice. An accurate follow-up is required.

Aged↗
PubMed1981

The management of keratocysts.

The clinical and histological data of 106 keratocysts from the files of the Department of Oral and Maxillofacial Surgery in Nijmegen and Arnhem, The Netherlands, formed the basis of this study. There was a wide age range with a male predominance and with the mandibular third molar area and ramus being the most common sites involved. Special attention has been drawn to the various ways in which recurrent keratocysts may develop. In the present study the recurrence rate of two groups of patients, treated according to two different concepts in the surgical management of keratocysts, are compared. As a result of a 21-year follow-up on 92 keratocysts a rational approach to the surgical treatment to eliminate a high recurrence rate is suggested.

Adolescent↗