The purpose of this article is to introduce Optiflex (^TM), the first non-metal archwire in orthodontics. This clear archwire is comprised of three layers : a silicone dioxide core, a silicon resin middle layer and a stain-resistant nylon outer layer. It is available in two sizes : 0.017″ and 0.021″. Optiflex was compared to three other flexible archwires (Niti, Respond and Nitinol) by means of tensile, bending and time-dependent effects tests. The results showed that :
1. The tensile strength of Optiflex was significantly lower than that of metal archwires.
2. The force delivered by Optiflex was much lighter and more constant than those delivered by other archwires.
3. The force of Optiflex was less than half the force delivered by at “Respond” archwire of similar size.
4. Time-dependent effects of Optiflex were almost identical to those of nickel-titanium.
These mechanical advantages, along with its esthetic properties and stain resistance, make Optiflex a unique addition to orthodontic archwires currently available. The new archwire is highly effective in the alignment of crowding in most orthodontic cases, particularly adults with special esthetic considerations.

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The speech patterns of 10 normal Japanese were studied to establish a method for evaluating speech disorders from the standpoint of orofacial articulatory movements during the pronunciation of the following Japanese test sentence : “Sakura no hana ga sakimashita.”
To assess the speech pattern of each subject, 5 points on the median sagittal plane of each face were monitored : the subnasale (N), the vermilion border of the upper and lower lip (UL, LL), the menton (M), and the middle of the LL and M (LM). In addition, movement of the incisal point (IP) was represented by using a mandibular kinesiograph (MKG).
The following 2 images and the voice of each subject were simultaneously recorded on the same video tape by two high-speed TV cameras : (1) the face of each subject as the sentence was spoken or a CRT display of the MKG ; and (2) the voice spectrograms of each subject as depicted on a speech spectrographic display (SSD). Then, the recorded video tape was played back on a high-speed TV monitor and the scenes during which each of the consonants was pronounced were identified on spectrograms of the SSD. On the freeze frame images, the data was reduced by utilizing an electronic digitizing tablet. The trajectory of each monitored point during pronunciation of the test sound was then computed by an analyzer (Sportias 300) with respect to the following parameters : the total length from start to finish of the trajectory (TL); the distance between the start and finish of the trajectory (SL); the ratio of the TL to the SL (T/S); the antero-posterior range (X-R) and the vertical range (Y-R); the area of the rectangle encompassing the entire trajectory (AR); and the average of the angles made by the differences in the direction of the preceding and following trajectories at each measured time point (TH).
The results revealed that the mandible and each monitored reference point had specific trajectories during the pronunciation of/s, ∫, and m/in contrast to the other constants and vowels of the test sentence. Further, the movements of the IP, L, and M were generally similar, excepting the pronunciation of /m/ : the IP was rather steady and the UL moved downwards whereas the LL and M moved upwards. With regard to the entire articulatory movements of the test sentence, the TLs and ARs were larger in the following order : IP <M<LL, and, excepting the IP and LL, a statistically significant difference was noted (p<0.05). On comparing the trajectories of /s, ∫, and m/, the IP, M, LM and LL movements showed significant differences between /∫/ and /s, m/, but not the TL. Differences were noted between the trajectory of /s/ and /m/ in the X-R of M and LM, i.e., the /s/ trajectory was greater than the /m/ trajectory (p<0. 01).
These findings will help to provide standard patterns for diagnosing motor disorders of speech.

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Various-shaped and sized defects of human coronal enamel were illustrated by scanning electron microscopy. Small Tomes' process pits (TPP) and larger focal holes (FH) were usually present in the enamel surfaces. On the other hand, FH-like defects were often scattered in the regions adjacent to large enamel defects. Some TPP contained a smaller punched-out deep pit (POP). In the natural surfaces of hypoplastic enamel, keyhole-shaped prism structures (KHP) were observed. Some KHP also contained a POP. That is, the center of enamel prisms occasionally mineralized later than the other prism regions. Small deep holes, roughly equal to FH in diameter, were relatively rarely observed. In rare cases, large shallow and deep defects were observed, while minor irregular oval or slit-shaped defects with a depth up to 15 ym were scattered in the supracervical zones. In addition, the rows of conic-shaped defects running longitudinally or transversely were found in the supracervical zones. The floors of the large defects showed TPP, KHP, or afibrillar cementum-like structures as well as smooth enamel surfaces. FH and TPP occasionally with a smaller POP, which are usually present along the perikymatas, are formed by the final stage of normal amelogenesis, while the remaining pits and defects must have been caused by some hypoplastic enamel.

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The adaptation accuracy of a commercially available non-computer-aided ceramic system (CELAY system) to the MOD inlay model specified by the ADA was investigated by measuring the discrepancy between the top surface of the master die and the resin pattern or the ceramic inlay. Even when the resin pattern was prepared directly on the stainless master model, the ceramic inlay could not to be seated exactly on the master model. The discrepancy between the resin pattern and the master die (0.083 ±0.028 mm) was not significantly greater than that between the ceramic inlay and the master die (0.118±0.052 mm). However, this discrepancy was significantly decreased when the resin pattern was prepared in a stone model that had been coated with a resinous die spacer at a thickness of approximately 30 pm. However, it was still difficult to obtain a ceramic inlay which exactly fit the master model. These results suggest that greater effort should be devoted to improving the accuracy of resin pattern preparation and the milling apparatus itself.

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Since porcelain is brittle and the hardest restorative material, it was difficult to be finished smoothly enough with conventional dental mechanical polishing tools. Glazing has been used regularly for the final finishing procedure of porcelain. However, we sometimes faced the situation in which we had to finish porcelain restorations with mechanical buffing for example in which we could not perform glazing besides the patient in a clinic or we aimed to produce delicate surface gloss on the porcelain restorations in a laboratory. Recently polishing pastes for the buffing of porcelain are available on a market for this purpose. However, the composition and size of the polishing particles and their effects on the polishing efficiency have been unclarified. Therefore, in this study we analyzed the composition, shape and size of the particles and performed polishing experiments for fired porcelain samples using 9 kinds commercial pastes, industrial diamond pastes and alumina pastes. The surface texture especially surface gloss was examined. Results indicated that the diamond pastes could produce excellent surface with high gloss efficiently for all the samples in spite of the pre-prepared surface texture. On the other hand, the alumina pastes could produce excellent surface for only the sample with well pre-prepared texture. Commercials pastes improved surface gloss of the most self-glazed samples over 90 for 40 seconds and the main components and particle size distribution influenced the efficiency of improving surface gloss, which suggested that we have to select the material for the situation. These findings indicated the mechanical buffing of porcelain is useful and promising in both a clinic and a laboratory.

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The purpose of this study was to determine whether the application of pulsed electromagnetic fields (PEMFs) could accelerate bone formation in the midpalatal suture after rapid maxillary expansion. Nine adult male dogs were divided into three groups. Group 1 (N=1) was kept as a sham operation control. Group 2 (N=4) was treated for 2 weeks and then separated into a non-PEMF and a PEMF-stimulated subgroup. Group 3 (N=4) was also separated as group 2 was but treated for 3 weeks. The maxilla was rapidly expanded for 1 week and left for retention of 1 or 2 weeks. The experimental groups were stimulated by PEMFs for 10 hours daily. The PEMF appliance was set to produce the specific asymmetrical repetitive 200 its pulses in burst of 4.8 ms repeated at a 15 Hz rate. Tetracycline and calcein were intramuscularly injected at intervals according to the experimental schedule. Soft X-ray photographs were taken and frontal sections of undecalcified and decalcified tissues were prepared. Contact microradiographs were then taken and bone histomorphometry was applied to quantify the areas of new bone formation. After 2 or 3 weeks of PEMF stimulation, the bone formation rate and mineral apposition rate, including total new bone volume, in the experimental groups were significantly increased. The results suggested that PEMFs enhanced acceleration of bone formation rate in midpalatal suture after rapidly maxillary expansion treatment and should be considered for clinical orthodontic application in the near future.

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Antibacterial activity of filler powder (designated Apacider) was examined by in vitro growth inhibition assay of Streptococcus mutans IFO 13955. Apacider powder itself showed the growth inhibition effect against S. mutans. The Apacider also exhibited an effective inhibition even when it was mixed into a resin composite. The maximum inhibition activity was obtained at the filler concentration of 10 wt %. At the concentration of 15 to 40 wt % filler, those activities were the same as that of 10 wt % filler. Five wt % of the filler also showed the effect, but its activity was weaker than that of 10%. It took about 7 days to observe the effective inhibition activity at any filler concentrations. Color of Apacider-containing composite resin did not change and it has been keeping antibacterial activity even when those materials were exposed into an artificial saliva for 7 days. Direct tensile and compressive strength of the resin containing various concentrations of Apacider decreased slightly as compared with the composite resin without Apacider. But those values were still effective for clinical use. These results indicated that the composite resin containing Apacider could be useful as an antibacterial agent in the field of clinical dentistry.

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The full bracket method, the mainstream of so-called mechanotherapy, has some differences in therapy methods depending on the forms and materials of the appliances. Even with the same appliance or material, the way to reach the treatment goal is likely to be different because of differences in the orthodontic procedures of the therapist.
If the material used has a wide range of deformation, the use of a material that causes almost no permanent deformation after application and that has stable and effective power for orthodontics for a long time can improve the situation. Though the structural form of brackets differs in various edgewise methods now, tooth movement using elastic chains has recently been recognized as an effective treatment in terms of improved operability, harmlessness, and attractiveness. However, there is still room for improvement in marketed elastic chains in spite of improvements in the permanent deformation rate and discoloration.
In the present study, a polyethylene material different from thermoplastic, thermosetting polyurethane rubber was developed and its features were scientifically and technologically compared with those of marketed materials.
The chain of new material is adjustable in the range of about two times the traditional elongation percentage, is highly flexibile, and shows almost no permanent deformation for 30 days longer than the existing materials with a noticeable restoring force.
These of this material enables us to improve operability, remove uncertain orthodontic force caused by an elastic chain with permanent deformation, and give a continuous load which is optimal for tooth movement.
Furthermore, the favorable features found in term of color fastness against foods etc., improves attractiveness.

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The purpose of this study was to clarify the histological characteristics of soft palate in patients with congenital velopharyngeal incompetence, and to investigate its relationship with nasopharyngoscopy and speech analysis. The following results were obtained.
1) The absence of the musculus levator veli palati and musculus uvulae was found to varying degrees in the medial zone of the soft palate in all cases.
2) Histological examination of the musculus levator palati was classified into three subgroups : slight defect, moderate defect and severe defect.
3) Histological examination of the musculus uvulae was assigned to three subgroups : slight absence, moderade absence and serious absence.
4) Three-dimensional reconstruction views of the palatal muscles were also divided into slight defect, moderate defect and severe defect groups.
5) Nasopharyngoscopy indicated that the velopharyngeal function was affected by the degree of the muscle defect.
6) The degree of hypernasality was almost related to abnomality of the musculus levator veli palati.
7) The morphological abnormality influences velopharyngeal incompetence.

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A patient was applied by Brånemark implant in the mandible, because a block resection for radical therapy of chondrosarcoma created an oral invalid with in mastication. This paper describes a prosthetic-surgical treatment approach utilizing Brånemark implant in combination with iliac bone graft. While a-28-year-old woman had received reconstruction of resected mandible with iliac bone graft, she hadn't been rehabilitated with a removable prosthesis satisfactorily, and 8 years after reconstruction of the mandible with iliac bone, Brånemark implant was applied to the mandible. Ten months after ten fixtures were installed in the mandible, an abutment operation and prosthetic treatment were carried out successfully. We ascertained that Brånemark implant was an effective prosthetic method in such patient as those received reconstruction of the mandible with iliac bone graft.

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