Proper diagnosis and treatment planning are important for the placement of a dental implant. However, it seems to be impossible to evaluate the mandibular bone in a buccaLlingual direction by using conventional dental or panoramic radiography. We estimated that bone thickness was correlated with bone mineral content (BMC). Photodensitometric measurement of bone image on radiograph has been used widely as a quantitative indicator of BMC. The purpose of this study is to ascertain the relationship between the buccal-lingual thickness of mandibular bone and BMC by Photodensitometry using dental radiography.

The subject contrast of mandible was used as a parameter of BMC. The subjects were 41 adults (28 men and 13 women, aged 23-38 years with a mean of 26.7 years). BMC was evaluated by a densitometer on dental X-ray films of mandibular bone with a 0.2mm copper plate reference.Trabecular bone and cortical bone thickness in a buccal-lingual direction were measured on the occlusal radiograph using a digital caliper.

There were significant negative correlations between trabecular bone thickness and the sublect contrast of bone (r=-0.4338, p<0.01), and between cortical bone thickness and the sublect contrast of bone (r=-0.3187, p<0.05). These results suggest it is possible to estimate mandibular bone thickness by calculating the subject contrast of mandible using dental radiography.

Studies have been conducted to examine the strength of the bond between thermosetting facing resin and the surface of titaniuln pretreated with various primers or by other methods. The effect of titanium-based organic coupling agents were assessed in an attempt of improving the strength of adhesion between titanium and thermosetting facing resin and of searching for surface treatment agents which have a high affinity for titanium.

The bonding strength was also examined for specimens treated with Snicoater or conventional primers. The bonding strength of Silicoater-treated specimens was highest and of specimens treated with any primer was lower. Exposure to thermal cycles resulted in lower bonding strength of both Silicoater-treated specimens and primer-treated specimens. The strength of TTIP-treated specimens heated at 400℃ was higher than that of primer-treated specimens. Thus, it was suggested that TTIP would have a higher affinity for the surface of titanium than conventional primers, allowing better bonding strength and durability.

The objective of this study is to make sure whether classⅡ mechanics with classⅡelastics causes some abnormal stimuli on stomatognathic muscles, antigravity muscles, and equilibrium function or not, and if there are some abnormal stimuli on those things, whether they are temporary actions or permanent.A pair of oral appliances (Clear retainers) with class n elastic, havivg a pull of two hundred gram, for one side which attached lingual buttons for hooks was applied to five volunteer healthy adult men and changes of the electromyogram (EMG) and the electrogravitiogram (EGG) with the stabilometer were observed continuously. Total length (㎝), Length/Time (㎝/sec), Length/Envelope area (1/㎝), Rectangle area (㎡), Envelope area (㎡), Root mean square area (㎡), Deviation of mean of X (㎝), and Deviation of mean of Y (㎝) were analyzed from the EGG.The electromyographic activity of the anterior part of the temporal muscle, the center part of the masseter muscle, the center part of the sternocleidomastoid muscle, the posterior part of the trapezius muscle, and the center part of the gastrocnemius muscle were recorded simultaneously.The results of this study are indicated as follows:1. It was recognized tendentiously that an orthodontic force with classⅡelastics caused an unstable equilibrium function one day after application but then it adapted to the human body immediately.2. An appropriate orthodontic force with classⅡ elastics was considered also from subjective symptoms that there was not a possibility which could cause serious obstacle to the human body.3. Taking the EGG continuously while the mandibular position is changeable indicated the possibility which will become important information for having a harmonious mandibular position with the human body and allow dental treatment to progress smoothly.

New bone defect fillers (BDFs) were made from α-tricalcium phosphate and binders consisting of 50%-deacetylated chitosan with and without sodium alginate and diluted organic acid as solvent. Inflammatory response, bio-resorption and osteoconductivity were examined through studies with subcutaneous implantation of binders and bone implantation of BDFs. Histopathological images of host tissue were observed up to four weeks following implantation.The concentrations of acetic and citric acid at which chitosan dissolved exceeded 0.1 and 1.0 wt %, respectively. Adopting of chitosan thus made it possible to reduce acidity of the BDFs, which had not been possible in previous studies. Inflammatory response was higher for binder using chitosan alone than with chitosan and alginate, whereas it was scarcely different between kinds and concentrations of acid used. Bio-resorption was also higher for binder using chitosan alone than with chitosan and alginate. And it increased with acid concentration. Therefore, it was thought that inflammatory response and bio-resorption would appear possibly due to the water-soluble chitosan.In all bone implantations, the gap between the implanted bulk and bone cavity gradually was filled with newly-formed bone, thus diminishing the trabecular bone formation around the bulk. When citric acid was used, significantly higher conductivity was noted compared to acetic acid.Thus, it was suggested that adequate biocompatibility and osteoconductivity was clearly evident for all BDFs.