Risto-Pekka Happonen

Compositional dependence of bioactivity of glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2

The bioactivity, i.e., bone-bonding ability, of 26 glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2 was studied in vivo. This investigation of bioactivity was performed to establish the compositional dependence of bioactivity, and enabled a model to be developed that describes the relation between reactions in vivo and glass composition. Reactions in vivo were investigated by inserting glass implants into rabbit tibia for 8 weeks. The glasses and the surrounding tissue were examined using scanning electron microscopy (SEM), light microscopy, and energy-dispersive X-ray analysis (EDXA). For most of the glasses containing < 59 mol % SiO2, SEM and EDXA showed two distinct layers at the glass surface after implantation, one silica-rich and another containing calcium phosphate. The build-up of these layers in vivo was taken as a sign of bioactivity. The in vivo experiments showed that glasses in the investigated system are bioactive when they contain 14-30 mol % alkali oxides, 14-30 mol % alkaline earth oxides, and < 59 mol % SiO2. Glasses containing potassium and magnesium bonded to bone in a similar way as bioactive glasses developed so far.

Contact allergy to dental restorative materials in patients with oral lichenoid lesions

118 patients with oral lichenoid lesions (OLL) topographically related to dental fillings were patch tested (FT) to reveal contact allergy to restorative materials. 80 (67.8%) patients displayed positive PT reactions to metals of dental filling materials: 76 reactions were found to various mercury compounds. 4 to sodium aurothiosulphate, 3 to stannic chloride and 2 to silver nitrate. The positive patch lest reactions appeared more commonly in patients with restricted contact lesions (85.1%, type‐1 lesions) as compared to patients with lesions exceeding to the adjacent areas (38.6%, type‐2 lesions). The replacement of dental fillings was carried out in 62/80 PT‐positive and 15/38 PT‐negative patients. 28 out of 62 (45.2%) PT‐positive and 3/15(20%) PT‐negative patients showed complete healing of OLL after a mean follow‐up time of 16 months. Complete healing occurred in 29/54(54.0%) type‐1 and 2/23 (8.7%) type‐2 lesions. Topographical relation between the lesion and the filling material (restricted versus exceeding the contact area) indicated association of OLL lesion and the filling material, which could be further confirmed by patch testing in the majority of patients. The patch test series should include mercuric chloride (0.1%), mercury (0.5%) and mercury ammonium chloride (1.0%), each in pet.

Simple bone cyst: Review of the literature and analysis of 23 cases

A retrospective study of 23 simple bone cysts including analysis of clinical, radiographical, histopathological features and follow-up information was made. The age of the patients varied from 8 to 59 years (mean 21.4 years). All lesions were found in the mandible, and 2 of them were radiologically multilocular. A loose connective tissue lining was found histologically in 8 out of 17 cysts with the biopsy specimens available. At follow-up, 2 failures of the primary surgical treatment were noted. The results emphasize that a proper follow-up is required after the treatment of simple bone cyst.

Detection of human papillomavirus (HPV) structural antigens and DNA types in inverted papillomas and squamous cell carcinomas of the nasal cavities and paranasal sinuses.

To assess the suggested etiological role of human papillomavirus (HPV), biopsies from 14 patients operated on for an inverted papilloma (11 cases) and squamous cell carcinoma (3 cases) of the nasal cavity and paranasal sinuses were analysed for light microscopical evidence of HPV, by indirect immunoperoxidase (IP-PAP) to demonstrate HPV structural proteins, and using in situ DNA-hybridization to disclose the DNA of HPV types 6, 11 and 16. The majority of the inverted papillomas contained areas of metaplastic squamous cells, including koilocytes as well as dysplastic changes consistent with intra-epithelial neoplasia as described in uterine cervix. In 3 patients, frankly invasive squamous cell carcinomas were found, originating from dysplastic squamous epithelium. Of the 14 lesions, 7 (50%) expressed HPV antigens, usually confined to only a few cells close to the surface of the epithelium. None of the malignant lesions expressed HPV antigens. In situ DNA-hybridization disclosed HPV 11 DNA alone in 5 lesions, but none of the lesions contained HPV 6 DNA. HPV 16 DNA was found in 2 lesions as a single HPV type, and in 3 other lesions concomitant with HPV 11. All three carcinomas contained HPV 16 DNA. The HPV DNA distribution proved to be different from that found in the genital tract HPV lesions; HPV DNA was less abundant in the nasal papillomas, and it was also found in the basal and suprabasal cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Resolution of oral lichenoid lesions after replacement of amalgam restorations in patients allergic to mercury compounds

The significance of contact allergy in patients with various oral symptoms was studied. Positive patchtest reactions to mercury compounds were found in 21/91 patients. Of these, 18 had lichenoid lesions in oral mucosa in close contact to amalgam fillings, and three patients with contact allergy had neither amalgam fillings in their teeth nor visible oral lesions. Amalgam replacement was carried out in 15/18 symptomatic patients. The fillings were replaced with gold in three cases, composite resin fillings in six, glass ionomer in three and both gold and composite materials in three cases. In 10 patients there was complete replacement and in five it was restricted to the fillings adjacent to the mucosal lesions. After a mean follow‐up period of 3.2 years a complete cure was seen in seven patients, each of whom had had all their fillings changed. A marked improvement occurred in six patients, and there was no change in two.

Odontogenic myxoma: a radiographic study of 21 tumours

Radiological features of 21 odontogenic myxomas found in 14 women and 7 men were analysed. Ten of the tumors were unilocular and 11 were multilocular. Unilocular lesions were mostly located in the anterior and multilocular in the posterior areas of the jaws. Intralesional trabeculation was seen in all multilocular but only in 3 unilocular lesions. Because radiological appearance of myxoma may be essentially similar with many other lesions of the jaws careful radiological examination is mandatory for planning of proper treatment.

Temporal and spatial patterns of transforming growth factor-β1 expression in developing rat molars

Regulatory peptides of the TGF-beta family affect various aspects of embryonic development. Recent immunolocalization and in situ hybridization studies have demonstrated a specific time- and tissue-dependent expression of TGF-beta 1 in the developing mouse embryo. The purpose of this study was to evaluate the distribution of TGF-beta 1 within rat molars at different stages of development, using a well-characterized antibody, highly specific for TGF-beta 1, and immunohistochemical methods of detection. TGF-beta 1 was immunolocalized intensely within the ectodermally derived stellate reticulum and the mesenchyme of the dental papilla at the bell stage of development. Marked immunostaining was also evident in the papillary layer and the reduced dental organ subjacent to ameloblasts in the differentiation and secretory phases of amelogenesis. During the formation of coronal tissues and in the pre-eruptive phase, immunoreactive TGF-beta 1 was localized conspicuously within the dental follicle overlying the tooth germ. This temporospatial pattern of expression of TGF-beta 1 appears to correlate with specific events in morphogenesis, histogenesis and cytodifferentiation during tooth development.

Craniofacial morphology in preschool children with sleep-related breathing disorder and hypertrophy of tonsils.

The purpose of this study was to examine craniofacial morphology, pharyngeal airway space and hyoid bone position in preschool children with sleep‐related breathing disorder associated with hypertrophy of tonsils (SBDT). Thirty‐eight preschool children, mean age 4.7 y, with SBDT and with an apnoea index (AI) of 0 < AI <5, were divided into two groups. One consisted of 15 children with sleep‐related breathing disorder (SBD) and more than 75% of the tonsils visible (GUI) and the other of 23 children with SBD and 25–75% of the tonsils visible (Gil). The control group consisted of 31 children without ear, nose and throat disease and with GI (barely visible) tonsils. Compared with the controls, GUI children had a retrognathic mandible, a large posterior facial height, a large interincisal angle with retroclined lower incisors, a narrow pharyngeal airway space, an anterior tongue base position and a long soft palate. Compared with the controls, Gil children had a large anterior lower facial height and a short nasal floor. However, like the controls, Gil children did not have a retrognathic mandible.

Obliteration of the frontal sinus cavity with bioactive glass

Bioactive glass (BG) is a glass ceramic material. It has been used as surgical bone replacement material in ear and oral surgery, orthopedics, and dentistry.

Prophylactic use of phenoxymethylpenicillin and tinidazole in mandibular third molar surgery, a comparative placebo controlled clinical trial

A clinical double-blind placebo controlled trial was carried out in 136 patients to test the value of the prophylactic use of phenoxymethylpenicillin and tinidazole in mandibular third molar surgery. The three patient groups were uniform with regard to the background data such as age and weight of the patients and the clinical status of the operated tooth, as well as to the observations made at surgery. No statistically significant differences were found between the study groups in the parameters used for evaluation. The results indicate that neither penicillin nor tinidazole have more effect on postoperative complications following operative extraction of wisdom teeth, than placebo tablets.