[A phd completed. The effect of radiotherapy on oral mucosa cell morphology.] / Serie: Hora est. Het effect van radiotherapie op de morfologie van de orale mucosa.

The treatment of oral cancer usually consists of surgical removal of the tumour, possibly followed by radiotherapy. The purpose of this dissertation research was to investigate the effects of radiotherapy on the oral tissues, in particular the superficially positioned epithelial cells in the oral mucosa. Earlier studies with electron microscopy revealed that unradiated oral mucosa cells, when observed at high magnification, contain microplicae (ridges or folds). Together with various saliva components, these microplicae form a protective layer that offers defence against, for instance, microorganisms. Radiotherapy damages these microplicae and may even destroy them altogether. Studies have shown that this effect of radiation can be observed in animals as well as in humans. As the radiation dose increased (50 Gy or more) the destruction of the microplicae was more severe. With a dose of 60 Gy or more the microplicae completely disappeared. This process may play an important role in the occurrence of osteoradionecrosis in the jaw and failure of dental implants placed after radiotherapy.

Microplicae--Specialized Surface Structure of Epithelial Cells of Wet-Surfaced Oral Mucosa.

The surface structure of the superficial cells of the oral mucosa is decorated with numerous membrane ridges, termed microplicae (MPLs). The MPL structure is typical of the epithelial surfaces that are covered with protective mucus. Cell membrane MPLs are no longer seen as passive consequences of cellular activity. The interaction between MPLs and the mucins has been demonstrated, however the role of MPL structure seen on the upper surface of the oral epithelial cells is speculative. The cell surface is of potentially great significance, as it harbors many markers for refined prognosis and targets for oral mucosal diseases and cancer therapy. With these aspects in mind, we conducted the present review of the MPL structure and function in order to form the basis for further studies of MPLs of the oral epithelial cells.

[Notes concerning an overdenture on 2 implants as the standard for treating an edentulous mandible]. / Kanttekeningen bij een overkappingsprothese op 2 implantaten als gouden standaard voor de behandeling van een edentate onderkaak.

Patients with an edentulous mandible often have difficulty retaining conventional dentures. It was formerly the case that, as a rule, 4 implants were placed in the interforaminal area of the mandible in order to provide retention for the mandibular denture. A large body of research, however, revealed good results with 2 implants with various mesostructures. The 2 implant overdenture in the mandible has since become standard for edentulous patients. Research results indicate that this treatment should be the primary option under certain conditions. The appropriate types of care which are indicated by these conditions should, however, be carefully distinguished. Under certain anatomical conditions, such as a low and narrow alveolar ridge, exposed mandibular nerves, very low density alveolar bone (Class IV bone) and very sensitive mucous membranes, 4 implants are indicated. Patients who are less manually dextrous might be better served with 2 implants and a single mesostructure.

The use of Straumann Bone Ceramic in a maxillary sinus floor elevation procedure: a clinical, radiological, histological and histomorphometric evaluation with a 6-month healing period.

OBJECTIVES: In this study, we evaluated the quality and quantity of bone formation in maxillary sinus floor elevation procedure using a new fully synthetic biphasic calcium phosphate (BCP) consisting of a mixture of 60% hydroxyapatite and 40% of beta-tricalcium phosphate (Straumann Bone Ceramic). MATERIAL AND METHODS: A unilateral maxillary sinus floor elevation procedure was performed in six patients using 100% BCP. Biopsy retrieval for histological and histomorphometric analysis was carried out before implant placement after a 6-month healing period. RESULTS: In this study, the maxillary sinus floor elevation procedure with the use of BCP showed uneventful healing. Radiological evaluation after 6 months showed maintenance of vertical height gained immediately after surgery. Primary stability was achieved with all Straumann SLA dental implants of 4.1 mm diameter and 10 or 12 mm length. The implants appeared to be osseointegrated well after a 3-month healing period. Histological investigation showed no signs of inflammation. Cranial from the native alveolar bone, newly formed mineralized tissue was observed. Also, osteoid islands as well as connective tissue were seen around the BCP particles, cranial from the front of newly formed mineralized tissue. Close bone-to-substitute contact was observed. Histomorphometric analysis showed an average bone volume/total volume (BV/TV) of 27.3% [standard deviation (SD) 4.9], bone surface/total volume (BS/TV) 4.5 mm(2)/mm(3) (SD 1.1), trabecula-thickness (TbTh) 132.1 mum (SD 38.4), osteoid-volume/bone volume (OV/BV) 7.5% (SD 4.3), osteoid surface/bone surface (OS/BS) 41.3% (SD 28.5), osteoid thickness (O.Th) 13.3 mum (SD 4.7) and number of osteoclasts/total area (N.Oc/Tar) 4.4 1/mm (SD 5.7). CONCLUSIONS: Although a small number of patients were treated, this study provides radiological and histological evidence in humans confirming the suitability of this new BCP for vertical augmentation of the atrophied maxilla by means of a maxillary sinus floor elevation procedure allowing subsequent dental implant placement after a 6-month healing period. The newly formed bone had a trabecular structure and was in intimate contact with the substitute material, outlining the osteoconductive properties of the BCP material. Bone maturation was evident by the presence of lamellar bone.

[Surgical dilemmas. Sinus floor elevation]. / Chirurgische dilemma's. De sinusbodemelevatie.

Limited alveolar bone height prevents the placement of dental implants. Sinus floor elevation is an internal augmentation of the maxillary sinus that allows implants to be placed. The principle of this surgical procedure is the preparation of a 'top hinge door', that is raised together with the Schneiderian membrane in the cranial direction. The space which created under this lid is filled with a bone transplant. Autogenous bone is the standard transplant material, despite the fact that a second surgery site is necessary. Under certain circumstances bone substitutes can be used, with a longer healing phase. If sufficient alveolar bone height is available to secure implant stability, simultaneous implantation and sinus floor elevation are possible. Considering the significant anatomical variation in the region of the maxillary sinus, a sound knowledge of the anatomy is of great importance.

[Recommendations in oral implantology]. / Aanbevelingen voor orale implantologie.

Oral implantology is a fast growing and dynamic specialization. An increasing number of dental professionals are carrying out oral implant treatments. Recommendations for oral implant treatments are needed to improve and manage treatment quality. In this article recommendations are proposed for 4 oral implant and superstructure indications in patients without complicating factors. The 4 oral implant indications are a mandibular complete overdenture, a maxillary complete overdenture, a single crown in the maxillary aesthetic region, and crowns and fixed partial dentures in the non-aesthetic region. The recommendations are also related to diagnostics and aftercare.

The use of a biphasic calcium phosphate in a maxillary sinus floor elevation procedure: a clinical, radiological, histological, and histomorphometric evaluation with 9- and 12-month healing times.

BACKGROUND: This study evaluates the clinical, radiological, histological, and histomorphometric aspects of a fully synthetic biphasic calcium phosphate (BCP) (60% hydroxyapatite and 40% ß-tricalcium phosphate), used in a human maxillary sinus floor elevation (MSFE) procedure with 9- and 12-month healing time. METHODS: A unilateral MSFE procedure, using 100% BCP, was performed in two series of five patients with healing times of 9 and 12 months respectively. Clinical and radiological parameters were measured up to 5 years postoperatively. Biopsy retrieval was carried out during dental implants placement. Histology and histomorphometry were performed on 5-µm sections of undecalcified bone biopsies. RESULTS: The MSFE procedure with BCP showed uneventful healing in all cases. All dental implants appeared to be well osseointegrated after 3 months. Radiological evaluation showed less than 1 mm tissue height loss from MSFE to the 5-year follow-up examination. No signs of inflammation were detected on histological examination. Newly formed mineralized tissue was found cranially from the native bone. The BCP particles were surrounded by connective tissue, osteoid islands, and newly formed bone. Mineralized bone tissue was in intimate contact with the BCP particles. After 12 months, remnants of BCP were still present. The newly formed bone had a trabecular structure. Bone maturation was demonstrated by the presence of lamellar bone. Histomorphometric analysis showed at 9 and 12 months respectively an average vital bone volume/total volume of 35.2 and 28.2%, bone surface/total volume of 4.2 mm2/mm3 and 8.3 mm2/mm3, trabecular thickness of 224.7 and 66.7 µm, osteoid volume/bone volume of 8.8 and 3.4%, osteoid surface/bone surface (OS/BS) of 42.4 and 8.2%, and osteoid thickness of 93.9 and 13.6 µm. CONCLUSIONS: MFSE with BCP resulted in new bone formation within the augmented sinus floor and allowed the osseointegration of dental implants in both groups. From a histological and histomorphometric perspective, a 9-month healing time for this type of BCP may be the optimal time for placement of dental implants.

Melkersson-Rosenthal syndrome in a patient with sero-negative oligoarthritis.

The Melkersson-Rosenthal syndrome is a rare disease consisting of orofacial swellings, facial nerve palsy and plicated tongue. The etiology is unknown. On histopathological examination a characteristic granulomatous inflammation is found. A case of this syndrome in a young white female with seronegative oligoarthritis is described and the possible relationship between the two diseases is discussed on the basis of the literature.

Hemorrhage of the floor of the mouth resulting from lingual perforation during implant placement: a clinical report.

The edentulous mandible provides a frequent indication for oral implants. In many cases implants are placed in the interforaminal region to support fixed prostheses or give retention to removable overdentures. One of the hazards of this seemingly safe surgical area is hemorrhage of the floor of the mouth. In this article, two cases of this life-threatening complication are reported.

Parallelism of hollow-cylinder ITI implants: an experimental study.

Site preparation for oral implants is a delicate surgical procedure. In the ITI F-type and Bonefit implant systems, two cylindrical burs are available. Experiments were performed to verify the clinical experience that the longer bur is more accurate in defining the direction of implants. Several preparations were made in six human femur heads. The purpose of the experiments was to investigate the difference in parallelism between preparations made with the standard cylindrical bur and the bur with the long shaft. The results showed that the bur with the longer shaft was preferred for obtaining an accurate direction and parallelism of the implants.

Short (6-mm) nonsubmerged dental implants: results of a Multicenter clinical trial of 1 to 7 years.

Limited bone height restricts the use of long dental implants, so short implants may be selected in these situations. Recent reports on clinical results with short implants have been negative, however, and have suggested that indications for the use of these implants are limited. To verify these findings, a multicenter study of short ITI implants was carried out. In a 6-year period 253 short implants with a length of 6 mm were placed into 126 patients, who were followed up from 1 to 7 years. Altogether 7 implants were removed; 6 of these were located in the maxilla and 1 in the mandible. The quality of survival was comparable with the clinical results of longer implants from the same implant system. Although the clinical results of these short implants were favorable, it is recommended that they be used in combination with longer implants, especially when used in the less dense bone that is often seen in the maxilla.

Explanation procedure with special emphasis on the ITI implant system.

Removal of implants is performed in cases of irreversible implant failure and in patients having psychological problems with implants. The explantation procedure can be complicated in some situations. In the present article, techniques of explantation and some related considerations are presented.

Explantation procedure in the F-type and Bonefit ITI implant system.

The explantation technique for the ITI F-type and Bonefit implant system is described. Although implant survival rates are high, the risk of failure must be considered. In some cases implants will have to be removed for reasons other than failure of the implant itself.

Parallelism of implants visualised on the orthopantomogram.

Orthopantomography is often used in implantology to determine the position of implants in the bone. Implants, which in fact are parallel, can be projected in a non-parallel position. Considerations inherent to the technique of orthopantomography are responsible for this phenomenon. In this study some experiments were carried out to demonstrate this. It can be concluded that orthopantomography cannot be used to determine whether implants are placed parallel or not.

Autogenous maxillary bone grafts in conjunction with placement of I.T.I. endosseous implants. A preliminary report.

Small bone defects due to atrophic, traumatic or periodontal bone loss can be grafted with autologous bone grafts taken from the maxillary tuberosity. This study presents a 1-3 years follow-up of 22 patients who were treated according to this technique. Thirty-two implants were placed 6 months after bone grafting. All implants were functioning well at the time of investigation.

[Application of hydroxyapatite as an implant in oral surgery: an overview]. / Hydroxylapatietgranulaat als implantatiemateriaal. Huidige stand van zaken.

An overview is presented of the clinical application of hydroxyapatite granulate as an implant material in atrophic, edentulous parts of the jaw.

[Dental implants: one or two stages?]. / Tandheelkundige implantaten: één- of tweefasig?

Dental implants can be inserted in one or two stages. The promoters of the two stages implant systems believe that submersion is essential for osseointegration. Animal and human studies, however, have shown that implants can also be successful when the one stage procedure is used. In this article the principles and the (dis)advantages of both procedures are discussed.

[Dental ITI-implants in the Netherlands: The evaluation of 2454 implants]. / ITI-implantaten in Nederland. Evaluatie van 2454 implantaten.

Between 1982 and January 1991, 2454 ITI Bonefit implants were placed in 841 patients. The clinical data were gathered from the departments of oral and maxillo-facial surgery at hospitals in Breda, Leiderdorp and Zwolle, the Netherlands. The follow-up ranges from one year to 9.5 years. A total of 48 implants were lost (2%).

[Pre-implantation surgery of the atrophied maxilla. A review of the literature]. / Pre-implantologische chirurgie bij de geatrofieerde bovenkaak. Een overzicht van de literatuur.

The aim of preprosthetic reconstructive surgery of the resorbed maxilla is to create sufficient bone of good quality for implant placement. The classification of the edentulous jaws by Cawood and Howell is mostly used as point of departure in planning preprosthetic reconstructive surgery. In this review article some procedures and results are mentioned as described in recent literature.