[Dissertations 25 years after date 22. Surgical treatment of keratocysts]. / Proefschriften 25 jaar na dato 22. Chirurgische behandeling van keratocysten.

In 1984, the dissertation 'The incredible keratocyst' was published. A postscriptum of this dissertation introduced a new and simplified approach in the treatment of keratocysts. Keratocysts are disreputable for a high recurrence prevalence and the new method is minimizing the chance of recurrence. The essence of the method is fixation of the cystwall with a modified Carnoy's solution before enucleation. During the past 25 years no new developments have been published concerning surgical treatment of keratocysts, which are essential divergent of this method. However, some authors have objections to the use of the modified Carnoy's solution because of feasible pathologic side effects. Based on research data and experiences of the author, it can be concluded that the fixing agent may be used without any risk.

Maxillary overdentures retained by splinted and unsplinted implants: a retrospective study.

The purpose of this retrospective study was to evaluate the clinical performance of and patients' satisfaction with maxillary overdentures retained by splinted and unsplinted implants. Patients who had been treated with maxillary implant-retained overdentures because of functional problems with conventional complete dentures were identified and invited to participate in the study. A total of 16 patients fulfilled the enrollment criteria and agreed to participate. Eleven patients were treated with bar-retained overdentures with 3 to 6 clips (mean follow-up 32 months), and 5 patients wore overdentures retained by 2 to 6 ball attachments (mean follow-up 54 months). All subjects were satisfied with their prostheses, and most subjects experienced improvement in their oral function after treatment with implant-retained overdentures. At the time of clinical examination, 92% (n = 77) of the 84 implants placed were functioning satisfactorily. The cumulative survival rate for the implants after 72 months was 90%. Loss of bone support correlated with peri-implant probing depth (r = 0.29; P < .02). No differences in mean bone loss between the subjects with ball-retained or bar-retained overdentures were found. The presence of plaque or peri-implant bleeding was not associated with the type of attachment.

[Abscesses caused by deciduous teeth]. / Abcessen uitgaande van melkelementen.

Abscesses in children, caused by deciduous teeth, ar not so frequently as seen in the permanent dentition. In most cases caries or an odontogenic infection of the associated deciduous tooth have already been treated by the dentist or oral surgeon at an earlier stage, i.e. before the infection exacerbates to an abscess. At the department of Oral and Maxillofacial Surgery of the Academic Hospital Nijmegen, between April 1997 and April 1998 20 children have been treated on a total of 1,693 patients with an odontogenic infection. Of this group, nine young children had an abscess caused by a deciduous tooth. In most cases the mandibular deciduous molars were involved. In one case an osteomyelitis of the mandible was diagnosed. All abscesses and infections could be treated adequately. The use of antibiotics is of paramount importance in the treatment of these abscesses in children.

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.

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.

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.

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.

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.

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.

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).

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.

[Is segmental osteotomy of the jaws outdated?]. / Is segmentosteotomie van kaken obsoleet?

In earlier days segmental osteotomies had a broad field of indications. In the era of combined surgical-orthodontic treatments, they are pushed far into the background. This article shows that this development is unjust. If carefully indicated, segmental osteotomies still have a well-defined place in our armory of surgical interventions. With their elegance and the compulsion to respect detail they are not only of marked didactic value, but they also fill a gap, especially in the treatment options for the lower jaw. Far from being obsolete, they should still belong to the routine options when orthognathic surgery is considered.

[The transmandibular implant. From bone loss to bone growth--an investigation of 116 patients]. / Het transmandibulaire implantaat. Van botverlies tot botgroei--een onderzoek bij 116 patiënten.

In a prospective study 116 consecutive patients were treated according to a revised protocol to induce and control bone growth. Revisions included: 1. lengthening of the transosseous posts and cortical screws between the mental foramina so that two threads extended beyond the alveolar crest of the mandible without protruding through the mucosa; and 2. fabricating an implant borne prosthesis with a gap of 2 mm between the denture base and the mucosal tissues in the saddle areas and loading only the retromolar pads. The gap was re-opened every 8 weeks until further bone growth would prevent proper oral hygiene. Measurements of the height of the mandible were made using a digital millimeter caliper and standardized radiographs. The radiographic enlargement was calculated per radiograph for the sites to be measured. The follow-up varied from 15 up to 39 months. Bone growth had occurred in 104 of the 116 patients, while the resorption of bone had ceased in the remaining patients. The increase of bone height varied from 9 mm in patients with severe mandibular atrophy down to 2 mm for patients with mild atrophy. The revised protocol for TMI insertion and rehabilitation is advocated to promote bone growth and to cease further resorption in the atrophic mandible.

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.

[Autotransplantation of teeth]. / Autotransplantatie van gebitselementen.

Autotransplantation of teeth has become a common procedure in oral surgery. The most usual procedures are autotransplantation of premolars, canines and third molars. The method can be performed on young patients in combination with orthodontic treatment, creating optimal occlusal relationship. Indication, selection and timing in connection with the surgical procedure are of paramount importance for optimal results.

[Germectomy. The germ of the third mandibular molar in children: remove or preserve?]. / Germectomie. De kiem van de derde molaar in de onderkaak bij kinderen: verwijderen of behouden?

Third molars are often removed in order to prevent complications and various other problems associated with impacted third molars and their removal. Abortion of mandibular third molars is a procedure carried out at an early age in those subjects where there is insufficient room for the eruption of the third molars. On the other hand one can also decide to remove the second molars and to annexate orthodontically the third molars in the arch.