Effect of procedure on diametral tensile strength of composite resin.

The sensitivity of the test for diametral tensile strength to variations in testing procedure was investigated. Composite resin specimens of four different surface roughnesses at both ends of the specimens were loaded at one of three crosshead speeds. The diametral tensile strength values varied between 43.9 and 65.7 MPa. Diametral tensile strength was found to decrease with increasing loading rate, with decreasing roughness of the specimens, and with increasing length of the cylindrical specimens. The significant influence of the surface roughness is suggested to be a result of the correlation between roughness and length of specimens, and not the expression of a true influence on diametral tensile strength of surface roughness of the specimens' ends.     

A standardized method of X-ray CT for sagittal splitting osteotomy of the mandibular ramus

A useful standardized method of X-ray computed tomography (CT) was proposed for the preoperative examination of sagittal splitting osteotomy of the mandibular ramus. In our assessment conducted for cases of mandibular prognathism operated on by a modified technique, the most informative CT image of the mandibular ramus was provided by the scans between the upper and lower dentitions in the open mouth position at which the scan-plane angulation was given as parallel to the dentition in each jaw. These sections enabled preoperative assessment on the mesio-lateral thickness of the marrow space and the positional relationship between the ramal cortices and the mandibular canal together with other geography of the ramal bone structure. Using these CT images, the plane of sagittal osteotomy is predictable. A technique for obtaining standardized CT slice is proposed in this report.     

Prosthetic treatment by pushing back part of the hard palate in third-degree cleft palate

In the third degree of cleft palate, the palate bones are short, the cleft is wide, the degree of palatal tissue atrophy and the anterior displacement of the muscles are great. It is difficult to repair satisfactorily. We carried out a treatment plan by pushing the soft palate and posterior part of the palatal bone fully back to the physiological closure position by surgical means without cutting through the palatal aponeurosis. By using a palatal plate with pharyngeal prong immediately after operation to fix the composite flap posteriorly and restore the defect of the hard palate. The palatal palate is changed with a silicon obturator or performed secondary operation to repair the perforation of the hard palate after the primary wound is well healed. 24 cases have been performed by this means since 1984. The outcomes are good. It is well conditioned for surgical orthodontics of severe crossbite which results from undeveloped maxilla also.     

The influence of surface free-energy on planimetric plaque growth in man

The purpose of this study was to examine the change in plaque area over nine days in vivo on four materials with different surface free-energies (s.f.e.). Twelve healthy dental students participated in a cross-over, split-mouth, double-blind study. Supragingival plaque formation was recorded over a nine-day period, on four different materials: fluorethylenepropylene (Teflon) (FEP), parafilm (PAR), cellulose acetate (CA), and enamel (E) with s.f.e. of 20, 26, 57, and 88 erg/cm2, respectively. Strips made from the first three materials were stuck to the buccal surface of an upper incisor. The remaining incisor was carefully polished and served as an enamel surface. The increase in plaque was evaluated after three, six, and nine days. A planimetrical analysis was used so that the plaque area could be expressed as a percentage of the total buccal tooth surface. This procedure was repeated on each subject, so that at the end, each pair of central or lateral incisors received the four tested materials. The results indicated that the adherence of micro-organisms on pellicle-coated substrata was influenced by the material's s.f.e.; there was an association between the s.f.e. of the substrata and the supragingival plaque extension in vivo. High surface free-energy substrata in the oral cavity attracted more micro-organisms than did low energetic materials. Additionally, the bacterial adhesion seemed very weak on surfaces with a low s.f.e.     

Intermediate bone grafting of alveolar clefts

During the five year period 1980 to 1985 bone grafting was performed in 37 cleft patients before the eruption of the canine tooth (group IBG) and in 30 patients after the eruption of the canine tooth (group SGB). The initial healing was more favourable in the IBG group. In 72.5% of the clefts oro-nasal fistulae were present preoperatively. In all cases the fistulae were successfully closed. In the IBG group with orthodontic closure of the gap in the dental arch the interdental bone height in the grafted area was more than 75% of normal bone height in all clefts. In group SBG this situation was found in only 66% of the bone-grafted areas. There seems to be a clear relation between the age or the developmental stage of the canine tooth on the one hand and the possibility of orthodontic closure of the gap in the dental arch and good interdental bone height on the other hand. This also leads to the suggestion that if bone grafting to the alveolar cleft is required the operation should be performed before the eruption of the canine tooth on the cleft side.     

Prosthodontic management of the hydroxylapatite denture patient: a preliminary report

A 4-year study and evaluation of nonresorbable hydroxylapatite to augment different alveolar ridges has been reported. The technique used resulted in improved contour, height, and width of the alveolar ridge. It was found that denture comfort improved with ridge augmentation as this allowed improved stability, support, and preservation of the ridge. Patient satisfaction was correlated to both surgical and prosthodontic success with the use of hydroxylapatite. The state and health of the tissues were found to be improved with the use of hydroxylapatite or hydroxylapatite and bone marrow. The prosthetic and surgical procedures were found to be easier to perform, and they produced more permanent and superior results than those previously experienced with only bone grafts and other alloplasts.     

Assay of bone morphogenetic protein-2, -4, and -7 in human demineralized bone matrix

Demineralized bone matrix (DBM) is a widely used bone graft material that derives its osteoinductive potential from matrix-associated bone morphogenetic proteins (BMPs). Prior investigations have shown that the osteoinductive potential can vary widely, with influence from both donor and processing sources. Although it is plausible that donor variance in the BMP profile can be an important consideration, the few published studies available have given inconsistent and incomplete information about this. The goal was to (1) characterize the variance of BMP-2, BMP-4, and BMP-7 in fully demineralized DBM derived from 20 appropriately screened (Food and Drug Administration and the American Association of Tissue Banks criteria) donors (male and female, 17-65 years) and (2) using literature review, infer the potential for this to be an important source of variability in graft function. BMPs were extracted with 4 M guanidine hydrochloride, and levels of BMP-2, BMP-4, and BMP-7 were measured using enzyme-linked immunosorbent assay. Measured levels were as follows: BMP-2 = 21.4 +/- 12.0 ng/g DBM, BMP-4 = 5.45 +/- 2.04 ng/g DBM, and BMP-7 = 84.1 +/- 34.4 ng/g DBM, which were significantly different (P < 0.05). There was a positive linear correlation between BMP-2 and BMP-7 (P = 0.0227). DBM derived from female donors had significantly greater concentrations of BMP-2 and BMP-7 than did that derived from male donors (P = 0.0257 and 0.0245, respectively). There was no significant correlation between donor age and the levels of any of the measured BMPs. The magnitude of variance of BMP profile appears to reasonably well correspond to the variance in osteoinductive potential cited by others, suggesting the possibility of using this as a method of donor screening.     

Patient evaluation of outcomes of external rhinoplasty for unilateral cleft lip and palate

Thirty-five patients (range 16-59 years) with cleft-lip nasal deformity treated by external rhinoplasty were evaluated for satisfaction and perception of outcomes. Treatment involved alar base relocation and augmentation of the asymmetric nasal tip with auricular cartilage grafts. The patients completed a satisfaction survey and interview at the 2-year follow-up visit. A visual analogue scale (VAS) numbered 0-10 was also used by the patients to grade outcome compared to preoperative appearance at 4 anatomic sites. Prior to surgery, the nasal tip was perceived as being most deformed (15/35), followed by alar position (12/35) and nasal apertures (8/35). The site on the nose most improved by surgery was the tip (15), followed by alar position (10), symmetry of nostrils (6) and dorsum (4). The highest VAS score was for the tip (8.32), followed by alar position (7.59), dorsum (7.41) and symmetry of nostrils (6.73). No patients suffered long-term pain for more than 2 months following surgery. All patients were prepared to undergo such procedure for a second time, if necessary. The unilateral cleft-lip nasal deformity can be improved in the eyes of the patient, using the combination of external rhinoplasty with alar base relocation, where necessary, and auricular cartilage augmentation of the nasal tip.