Increased fluoride uptake and acid resistance by CO2 laser-irradiation through topically applied fluoride on human enamel in vitro.

OBJECTIVES: The aim of the current in vitro study was to evaluate the effect of CO(2)-laser treatment immediately after applying amine fluoride solution on enamel. It was hypothesized that such a treatment would increase enamel fluoride uptake, and reduce dissolution rate and thermal surface alterations. METHODS: Fluoride uptake was determined in 40 human enamel sections randomly assigned to four groups (n=10), which were either left untreated (1), exposed to a 1% amine fluoride solution for 15s without irradiation (2), irradiated for 15s with a continuous-wave carbon dioxide laser (3), or laser-treated for 15s through the amine fluoride solution applied immediately beforehand (4). Fluoride uptake was determined with an ion selective electrode after acid dissolution of the specimens (surface and subsurface layers). For the determination of acid resistance, another 40 enamel sections were treated according to the above protocol. Acid resistance was determined in surface and subsurface layers by measuring eluted calcium upon 3% lactic acid exposure with atomic absorption spectrometry. Enamel surface alterations after laser irradiation were monitored using scanning electron microscopy. RESULTS: Laser irradiation through the fluoride solution led to significantly higher fluoride contents in the surface enamel layer compared to fluoride treatment alone or laser treatment alone (p=0.002). Laser treatment with or without fluoride resulted in an increased acid resistance of enamel specimens. Fewer surface alterations were observed upon SEM examination of specimens irradiated through the amine fluoride solution compared to counterparts treated with laser only. CONCLUSIONS: CO(2) laser light application through an amine fluoride solution may be useful and effective in the prevention of caries.

Apical inflammatory root resorption: a correlative radiographic and histological assessment.

AIM: To assess the reliability of routine single radiographs in the diagnosis of inflammatory apical root resorption by correlating the radiographic and histological findings. METHODOLOGY: The material comprised serial and step serial sections of plastic-embedded root-apices with attached apical periodontitis lesions that were prepared for a previous study and the diagnostic radiographs. The histological sections of 114 specimens were analysed by light microscopy and categorized into three groups: (i) those without any resorption (0); (ii) those with moderate resorption (+); and (iii) those with severe resorption (+ +). The radiographs were examined by a separate examiner and graded with a similar categorization of no resorption (0); moderate (+); and severe (+ +) apical resorption. RESULTS: Radiographically, 19% of the teeth were diagnosed as having apical inflammatory root resorption, whereas histologically, 81% of the teeth revealed apical inflammatory root resorption. A correlative radiographic and histological assessment (n = 104) revealed a coincidence of diagnosis in 7% of the specimens and noncoincidence of diagnosis in 76% of the specimens. CONCLUSIONS: The results indicate that routine single radiographs are not sufficiently accurate or sensitive to consistently diagnose apical root resorptive defects developing as a consequence of apical periodontitis.

Types and incidence of human periapical lesions obtained with extracted teeth.

OBJECTIVES: To determine (1) the frequency of the incidence of abscess, granuloma, and radicular cyst among human periapical lesions obtained with extracted teeth; and (2) whether periapical cysts occur in two categories when histologically analyzed in relation to the root canals. STUDY DESIGN: A total of 256 lesions were analyzed. The specimens were decalcified and embedded in plastic. Serial sections or step-serial sections were prepared, and the sections were evaluated on the basis of predefined histopathologic criteria. RESULTS: The 256 specimens consisted of 35% periapical abscess, 50% granuloma, and 15% cysts. The latter occurred in two categories, the apical true cysts and the apical pocket cysts. CONCLUSIONS: These results show (1) the low incidence of radicular cysts among periapical lesions as against the widely held view that almost half of all periapical lesions are cysts; and (2) the occurrence of two classes of radicular cysts. We are of opinion that the pocket cysts may heal after root canal therapy but the true cysts are less likely to be resolved by conventional root canal treatment.

[Mandibular fractures due to implant management--incidence, mechanism of injury and therapeutic characteristics]. / Unterkieferfrakturen infolge Implantatversorgung--Inzidenz, Verletzungsmechanismen und therapeutische Besonderheiten.

We report of 5 of 337 patients (1.48%), in whom a fracture of the edentulous atrophied mandible occurred after dental implants had been inserted. In 79 patients a sandwich osteotomy (anterior and/or lateral mandible) had been carried out together with the insertion of implants. The reason for a fracture was infection in 3 patients and weakening of the atrophied mandible by the additional osteotomies in 2 patients. One of the latter two was seen intraoperatively and fixed immediately using miniplates. The other occurred about 4 weeks postoperatively and was not discovered until callus had been developed. Consequently only 4 of the 5 patients were treated by osteosynthesis. In two patients no implants were lost. The application of bone morphogenetic protein (BMP) helped to avoid the loss of implants because it accelerated ossification of the fracture and the integration of the implants.

[Severe complications after surgical removal of wisdom teeth]. / Schwerwiegende Komplikationen nach operativer Weisheitszahnentfernung.

Between 1988 and 1992, 14,765 impacted third molars were removed in the Department for Maxillofacial Surgery of the University Hospital and Dental Clinic in Zurich. A report on significant complications is given and compared to previous studies. Special attention is given to major complications which needed hospitalisation and/or surgical intervention, like secondary infection of the head and neck region, mediastinal emphysema, mandibular fractures and dislocation of third molars, which could not be removed under local anaesthesia. Mediastinitis, excessive bleeding or permanent damage to cranial nerves were not encountered in these 5 years, but are reviewed. Serious postoperative complications can be life-threatening if not diagnosed correctly and managed accordingly.

[The surgical removal of the lower wisdom teeth. Is open follow-up care still up-to-date?]. / Operative Entfernung unterer Weisheitszähne. Ist die offene Nachbehandlung noch modern?

The removal of lower wisdom teeth is one of the most common procedures in oral surgery. Postoperative complications have been reported in over 10% of the cases, of those being 8.5% due to infection. In our Department, the open wound healing method has been used routinely for more than 50 years. In this article we present a retrospective and a prospective study comparing the open and closed wound healing techniques after lower third molar removal. The retrospective study dealt with 908 consecutive cases of the year 1991 in which all postoperative complications were analysed. The prospective controlled randomized study dealt with 300 cases in which the open and the half closed wound treatment was compared. Preoperative data including the papillary bleeding index and the postoperative incidence of infections were analysed. In the open wound healing group, a complication rate of 3%, with less than 1% being infectious, was observed. In the group where a semi-closed procedure was performed, a complication rate of more than 13% with 6% infections was found. It could be demonstrated that poor oral hygiene influences the postoperative infection rate, especially in cases where the semi-closed wound healing was used, whereas open wound healing is less affected by the status of oral hygiene. In both methods approximately three postoperative consultations were necessary. Based on these results, the open wound healing method after surgical removal of lower wisdom teeth is advocated.

[Application of endosseous screw implants. Indications and planning]. / Die Verwendung enossaler schraubenförmiger Implantate. Indikation und Planung.

To achieve long term positive results for endosseous dental implants, three points have to be considered: the osséointegration, the correct indication and the suprastructural planification designed for the spécific type of implant. If the surgery part is done by a different practitioner as the prosthetic part, tight coworking for planning is necessary and the responsibility in each step has to be cleared in advance. The planification in implant cases is divided into three stages: clearing of contraindications, choice of the suprastructure, and the surgery planning. Aids for exact localisation of the implants are presented.

In-vitro formation of a new fibrous attachment to human dental roots in the presence of autologous serum.

Recent studies have accomplished the establishment of a collagenous fiber-fringe matrix upon dental root surfaces in vitro. The present study was undertaken to follow the development of such a matrix in vitro and to test the possible effects of root surface treatments upon this matrix. Periodontal ligament cells, 0.1 to 0.2-mm thick dental root discs, and alveolar bone cells were derived after extraction from four partially erupted third molars and the accompanying interradicular bony septa of 1 male patient. Autologous serum was obtained by venipuncture. Cultures were initiated by delivering a 1-ml suspension of 50,000 tritiated thymidine-labeled periodontal ligament cells and 50,000 alveolar bone cells onto each of 42 culture sets. The following day, demineralized or non-demineralized root discs treated with autologous serum, fibronectin or complete medium were placed in pairs, separated by a 0.1-1.0 mm gap, upon the initial cell layer. Representative cultures were terminated after 2, 3, 4, 5 and 6 weeks, and processed for light- and electron microscopy, morphometric analysis and autoradiography. An outstanding feature of the early cultures (2, 3 and 4 weeks) was a patchwise, random distribution of matrix making a precise developmental study impossible, although collagen fibrils were produced within the first 2 weeks. Some 3-week cultures already demonstrated a mature fiber-fringe characterized electron-microscopically as oriented, densely packed collagen fibrils closely abutting the cementum-lined root discs. The treatments (including autologous serum) used in this study had no appreciable morphologic or morphometric effect upon the fiber-fringe formed. Because none of the cultures in the present or past studies have demonstrated a true cementoid matrix, this model may not be suitable for the in-vitro study of cementum formation.

Experiences on the sequela of maxillary sinusitis following closure of the causative oro-antral fistula.

After describing the method of treating sinusitis in established oro-antral fistulae, which consists of irrigation of the maxillary sinus, antibiotic therapy and closure of the fistula, our experience gained on 75 cases checked postoperatively is presented. We found that a radical operation of the sinus, even later, was not necessary in most cases (present investigation of our clinical material showed 97.3 per cent). The inflammatorily a altered mucosa recovers after the elimination of the causative factor, which in this case is the closure of the oro-antral fistula. These findings thus correlate with those made by Obwegeser a and Tschamer (1957) and by Killey and Kay (1967).