Kokubyo Gakkai zasshi. The Journal of the Stomatological Society, Japan最新文献

The functions of articulation and mastication after glossectomy for tongue carcinoma were sequentially assessed. Longitudinal assessment of articulatory and masticatory functions was analyzed in 64 tongue cancer patients who underwent partial glossectomy (partial glossectomy group: 40 cases) or hemiglossectomy (hemiglossectomy group: 24 cases) in our department between January 2007 and August 2008. The mean age of the 64 patients (37 men, 27 women) was 56.9 years, ranging from 21 to 82 years. Tongue mobility was assessed using a tongue movement function test by Matsunaga's classification. Articulatory function was assessed using the monosyllable Japanese speech intelligibility test, while masticatory function was evaluated using color-changeable chewing gum and occlusal force score using Yamamoto's classification. The functions were evaluated preoperatively, and 1 month, 3 months, 6 months, and 12 months postoperatively. In all groups, both tongue movement and articulatory and masticatory functions were impaired 1 month after surgery, however they gradually recovered between 3 to 6 months and reached a plateau from 6 to 12 months. The values of the parameters in the partial glossectomy group and the hemiglossectomy group at 6 months postoperatively were respectively as follows : the tongue movement function scores were 6.9+/-0.4, 5.2+/-0.8; the speech intelligibility scores were 94.1+/-3.5%, 88.8+/-9.9%; the occlusal force scores by Yamamoto's classification were 5.3+/-0.9, 3.7+/-1.0; and the values of a* determined using the chewing gum were 13.8+/-2.4, 8.6+/-3.5. In addition, there was a correlation between speech intelligibility and the value of a*, and between speech intelligibility and occlusal force scores by Yamamoto's classification.

Purpose of this study was to determine the relationship between food mixing ability and oral health-related quality of life (OHR QoL) in partially edentulous patients with removable partial dentures. One hundred and thirty one patients (mean age 67.1 years) participated in this study. The subjects comprised patients who were treated with removable partial dentures (RPDs) in an undergraduate program (n=52), those who were receiving oral maintenance care (n=57) and those who planned to replace current RPDs with new ones (n=22), and OHR QoL was measured using the oral health impact profile-Japanese version (OHIP-J). To evaluate food mixing ability, the subjects were asked to chew a two-colored paraffin wax cube as a test item. Mixing ability index was determined from the color mixture and shape of the chewed cube. Spearman rank correlation coefficient was used to test the relationship between mixing ability index and scores of OHIP-J. No significant correlations were found between mixing ability index and scores of OHIP-J in each group (p>0.08). The results suggest that association between food mixing ability and OHR QoL life is very weak in partially edentulous patients with RPDs.

Recently, new metal free materials for crown and bridges such as yttria stabilized tetragonal zirconia polycrystals (Y-TZP) have been introduced in the dental profession. These systems enable the fabrication of long-span bridges of more than 3 units in the posterior region. But occasionally chipping of the veneering porcelain was observed. The aim of this study was to analyze the influence of the design of the zirconia framework on the fracture strength of the veneering porcelain. Two types of Y-TZP framework were fabricated for the lower second premolar crown (normal type and support type) (Cercon base colored, DeguDent, Hanau-Wolfgang, Germany). The support-type framework has a 1 mm-wide collar around the margin to support the veneering porcelain. Twelve all-ceramic crowns were fabricated, six crowns for each group. The framework was covered by veneering ceramics (Vintage ZR Press Over, SHOFU INC., Kyoto, Japan) using the heat press method. All specimens were fixed using adhesive resin cement on the master die and the vertically loaded was measured at the distal ridge of the crown at a cross-head speed of 1 mm/min until fracture. The maximum compressive load required to cause a fracture was recorded for each specimen. The t test was used for the statistical analysis of the fracture loads, with a significance level of alpha = 0.05. The following conclusion was obtained. The fracture strength of the all-ceramic crowns with a support-type Y-TZP framework was significantly higher than that of the normal type. This result suggests that the design of the Y-TZP framework is important for all-ceramic restorations.

The connecting rigidity of the retainer and the denture supporting area may influence the distribution of the occlusal load. Three types of retainers (wrought wire clasp, Akers cast clasp and conical crown telescopic retainer) and three outline forms of denture bases designed for distal extension removable partial dentures were assessed in six patients with Kennedy Class II situations. To evaluate the influence of oral function, mandibular displacement, abutment tooth displacement, and denture base exerted pressure were measured simultaneously during maximum voluntary clenching. The mandibular displacement increased when the connecting rigidity decreased or the size of the denture base was reduced. The abutment tooth displacement increased as the denture base was reduced with the Akers clasp. The denture base pressure increased as the denture base reduced with the wrought wire clasp. The conical crown telescopic retainer did not cause overloading to the supporting tissues even when the denture base was reduced. It was also revealed that the abutment tooth tended to displace distally when a distal occlusal rest was prepared on the abutment tooth.

Much research has been reported about post and core systems with composite resin, but the influence of the different types of prefabricated posts on the distribution of stress in the root has not yet been elucidated. It is necessary to clarify the influence of the relationship between core and crown materials to obtain combined restorations. The aim of this study is to analyze the influence of the combination of various post and core systems and different kinds of crown material on the stress distribution in the root. Six 2-dimensional photoelastic premolar models were designed. Three types of post and core systems (composite resin post and core, composite resin core with the fiber post, and composite resin core with a prefabricated stainless steel post) and two kinds of crown materials (metal and hybrid-type hard composite resin) were fabricated and cemented to each model. In these models, we applied a load of 200 N at an angle of 45 degrees to the tooth axis and analyzed the fringe order using a transmission polariscope. As a result, it has been clarified that the combination of the post and core and the crown plays an important role in preventing stress concentration within root Stress concentration can be prevented using a crown fabricated with a high-elastic modulus for the post and core with a high-elastic modulus, and a crown fabricated with a low-elastic modulus for the post and core with a low-elastic modulus.

A surgical guiding system with simulation software has recently been used for safe implant treatment. We report a clinical case in which we successfully used this system for implant treatment of a congenital tooth missing region with severely restricted mesiodistal space. The patient was a 19-year-old female whose mandibular right deciduous canine was wobbling without a successional permanent tooth and who desired implant treatment. CT images showed that this site was narrow buccal-lingually and only five millimeters in mesiodistal width. The implant position was planned using simulation software (SimPlant : Materialise Dental) based on CT data and a surgical guide template (SurgiGuide : Materialise Dental) was fabricated prior to the implant surgery. During the implant surgery, the deciduous canine was extracted under local anesthesia. The implant bed was prepared with the surgical guide template and an implant was installed. One month after surgery, the position of the implant was examined with a cone-beam CT, which demonstrated that the implant position was exactly the same as planned. At 5 months, a provisional prosthesis was delivered and optimal soft-tissue condition was formed by modifying the provisional prosthesis. Then, the final impression was taken and a ceramo-metal implant-supported crown was delivered. In this case of a congenital tooth missing region with narrow space, implant treatment with simulation software and the surgical guide system provided excellent clinical results.

For better understanding of the structures comprising the human body and in view of the possible need for future revision, Latin anatomical names of skeletal foramina in Terminologia Anatomica were analyzed and classified, and compared with the corresponding Japanese anatomical names. The words following Foramen or Foramina indicated:1) the form of the foramen, 2) the state of the foramen, 3) the absolute size of the foramen, 4) the structure to which the foramen belongs, 5) the position of the foramen in the skeletal system, 6) the part of the human body in which the foramen exists, 7) the structure that transmits the foramen, or 8) the function of the foramen. Analysis of Latin names and comparison with Japanese names clarified some characteristics of both names and revealed some problems in them.

Although there have been several reports about fiber-reinforced composite (FRC) fixed partial denture designs, different framework designs have not been sufficiently assessed. This study analyzed the differences between varying framework designs using FRC materials by two-dimensional photoelastic observation. Seven study models with a three-unit fixed partial denture replacing the first molar were fabricated. One without FRC was used as a control, and the other six were divided in two groups: one with the framework partially covering abutments, and the other with the framework completely covering abutments. For each group, the middle part of the framework was made with three different designs: straight bar, curved bar and curved-thickened bar. A vertical force of 400 N was applied to the occlusal center of each model. The resultant stress was observed photoelastically and recorded photographically. We found that the FRC framework provided strength support to the overall structure, and that the framework completely covering abutments with the curved-thickened bar showed the lowest stress level.

The objectives of this study were to elucidate the influence of occlusal hypofunction on the histological structure of periodontal ligament (PDL) and on the cell proliferation and alkaline phosphatase (ALP) activities of cultured PDL cells isolated from PDL. Forty-two male Wister rats were divided into three groups: two experimental groups and one untreated control group. Occlusal hypofunction was generated in the molar region in the experimental groups for 3 or 7 days. Paraffin sections of the upper molar region were stained with H.E. or ALP for light-microscope observation. PDL cells isolated from molars of each group were cultured for 7 days for cytological analyses. Cell proliferation (BrdU labeling) and ALP activity of the three groups were compared. Change in the width of the PDL space, loss of functional arrangement of PDL fibers and reduction of PDL cell number were observed among molars of the experimental groups compared with the control group. ALP activity was increased in the molar region where significant enhancement of bone morphogenesis had not yet occurred. The ratio of BrdU positive cells was significantly lower and ALP activity was higher than that of the control group among cultured cells from molars of the experimental groups and the control group. The results clearly showed that occlusal hypofunction alters the histological characteristics of PDL even in a short time. Occlusal hypofunction reduces the cell proliferation and increases the ALP activity of PDL cells. The influence of occlusal hypofunction memory on cells is retained for at least 7 days in vitro.

To clarify the extent to which patients feel anxious about dental treatment, anonymized data of a self-completed questionnaire obtained at a dental clinic in Saitama Prefecture were used for this study. The subjects were 278 patients older than 15 years of age and who had given informed consent The questionnaire contained 71 questions concerning the following seven characteristic factors: sense of hearing, sense of sight, sense of smell, sense of taste, sense of touch, sense of pain, and other situations. Each question was rated on a four-point scale. Exploratory factor analysis of the 262 answers was performed with the principal factor method and normalized varimax rotation. Six factors were extracted using the Kaiser Criterion and the Screeplot These factors were interpreted as follows: anxiety before treatment, unpleasantness of pain and bleeding, unpleasantness of smell and taste or feeling of the tongue, a sound or appliance that recalled pain, a meaningful sound such as talking by the dentist, and an unpleasant sound from an appliance. The senses of smell, taste and touch in the oral cavity were extracted as the same factor. The sense of hearing was divided into the factor of dissonance and the factor of anxiety recalled by sound in memory. However, no factor concerning the stimulation of sight was extracted. Therefore, the sense of sight might be related with the recognition method of the patient based on past experience and knowledge.