The influence of healing type on marginal bone levels of implants supporting mandibular overdentures: a randomized clinical study.

AIM: The aim of this study was to document the influence of healing type on the marginal bone loss around dental implants placed in the anterior mandible. MATERIALS AND METHODS: A total of 48 edentulous patients rehabilitated with 96 Astra Tech dental implants left to either submerged or nonsubmerged healing were included in the study group. The patients were examined in consecutive routine recall sessions six, 12, and 24 months after loading. The actual bone level measurements were performed by two independent examiners on panoramic X-rays, and the average of both examiners' calculations was used as the marginal bone level value. RESULTS: The marginal bone loss (MBL) of the implants at 6 months was found to be significantly higher in the submerged healing group (P< 0.05). No statistically significant relation was found between the MBL of implants left to submerged healing and that of implants left to non-submerged healing in the other follow-up periods. CONCLUSION: In situations where the dental implant has good primary stability, non-submerged healing can be recommended to avoid a second surgery for healing abutment connection.

Two-body wear of occlusal splint materials.

This study investigates the wear resistance of four different types of occlusal splint materials based on two-body wear simulations under wet and dry conditions. Twenty specimens of each splint material (Dentalon Plus, Orthoplast, Biocryl C, and Eclipse), each with a diameter of 16 mm and a thickness of 3 mm, were tested, half under wet and half under dry conditions. Each wear test was performed using a device called chewing simulator CS-4 (n=10; test load: 50 N; number of cycles: 10000, 20000, and 30000; continuous rinsing with 30°C water for wet conditions); the antagonists were simulated using steel balls. Wear was determined using a 3D laser scanner and a surface analysis program. To detect significant statistical differences, wear data after 10000; 20000; and 30000 cycles were compared using the Kruskal-Wallis test and the Mann-Whitney U-test. The level of significance was set at 5%. Significant differences were found between the groups of different materials tested under wet conditions (P<0.05), whereas no differences between them were found under dry conditions (P>0.05). No significant difference was found between the wet and dry conditions for all materials and cycles (P>0.05). For groups of different materials tested under wet conditions, the degree of volume loss generated in the Chewing Simulator CS-4 was found to differ significantly for different numbers of cycles. The presence of water had no effect on the volume loss in the different material groups that were tested.

A comparative in vitro evaluation of two different magnetic devices detecting the stability of osseo-integrated implants.

BACKGROUND AND OBJECTIVE: It is unknown whether the resonance frequency analysis (RFA) measurements made by two different magnetic resonance frequency analysers are comparable. This in vitro study was designed to compare the RFA measurements made by the two magnetic resonance frequency analysers and to evaluate the intra- and interobserver reliability of the magnetic devices. MATERIAL AND METHODS: Thirty-two implants were placed in four cow ribs. The RFA value of each implant was measured by five different examiners. The measurements were repeated five times, in both the buccal and mesial directions, for each implant at 2 h intervals, and the averages of registered implant stability quotient (ISQ) units were recorded as the buccal ISQ value and the mesial ISQ value for every implant. RESULTS: No statistically significant differences (p>0.05) were observed between the RFA measurements made by the two magnetic devices. The intra-observer reliability of both devices was excellent, whereas the interobserver reliability of the devices was poor. CONCLUSION: The results of the RFA measurements of both tested devices overlap. Although both devices show excellent intra-observer reliability, there are variations between the measurements of different examiners.

Influence of surgical technique, implant shape and diameter on the primary stability in cancellous bone.

Achievement of primary stability during surgical placement of dental implants is one of the most important factors for successful osseointegration depending on various anatomical, surgical and implant-related factors. Resonance frequency analysis (RFA) has been shown as a non-invasive and objective technique for measuring the stability of implants. The aim of this study was to evaluate the effect of some surgical and implant-related factors in enhancing primary stability and to estimate a correlation between RFA and insertion torque (IT) in proximal regions of cow ribs representing cancellous bone. Fifteen implant beds were prepared in the most proximal region of six fresh cow ribs. Ninety implants with three different shapes and two different diameters were placed with two different surgical techniques, and the primary stability was compared using RFA and IT. Significantly higher RFA and IT values were achieved when under-dimensioned drilling was used as the surgical method (P<0·01); significantly higher IT values were obtained with the use of wider implants (P<0·01) and partially conical Astra Tech implants showed the highest IT values (P<0·01). When all the implants were considered, significant correlations between the IT and RFA values were noted (%40·6, P<0·05). Partially conical implants with a wide diameter to be placed with the modified surgical technique proposed appear to be useful in enhancing the primary stability in cancellous bone.

Parathyroid agenesis: prenatal ultrasonographic features and pathological findings.

We report a girl with parathyroid agenesis. The gross anomaly of the long bones was diagnosed prenatally by ultrasound. Pregnancy was terminated at 24 weeks of gestation. There were no other apparent system anomalies except parathyroid gland agenesis and long bone abnormalities. This case is the first reported case of parathyroid agenesis with normal thyroid glands and other systems.

Assessment of outcome of carpal tunnel syndrome: a comparison of electrophysiological findings and a self-administered Boston questionnaire.

The relationship between nerve conduction studies and the self-administered Boston Questionnaire that measures the severity of symptoms and functional status in carpal tunnel syndrome was assessed in 44 patients with idiopathic carpal tunnel syndrome. The patients were examined preoperatively and 3 and 6 months postoperatively. Although both the clinical outcome and electrophysiological findings improved significantly after surgery, we observed no correlation between improvements in nerve conduction and the questionnaire scores.

Clinical and genetic studies on 12 preaxial polydactyly families and refinement of the localisation of the gene responsible to a 1.9 cM region on chromosome 7q36.

Polydactyly is the most frequently observed congenital hand malformation with a prevalence between 5 and 19 per 10000 live births. It can occur as an isolated disorder, in association with other hand/foot malformations, or as a part of a syndrome, and is usually inherited as an autosomal dominant trait. According to its anatomical location, polydactyly can be generally subdivided into pre- and postaxial forms. Recently, a gene responsible for preaxial polydactyly types II and III, as well as complex polysyndactyly, has been localised to chromosome 7q36. In order to facilitate the search for the underlying genetic defect, we ascertained 12 additional families of different ethnic origin affected with preaxial polydactyly. Eleven of the kindreds investigated could be linked to chromosome 7q36, enabling us to refine the critical region for the preaxial polydactyly gene to a region of 1.9 cM. Our findings also indicate that radial and tibial dysplasia/aplasia can be associated with preaxial polydactyly on chromosome 7q36. Combining our results with other studies suggests that all non-syndromic preaxial polydactylies associated with triphalangism of the thumb are caused by a single genetic locus, but that there is genetic heterogeneity for preaxial polydactyly associated with duplications of biphalangeal thumbs. Comparison of the phenotypic and genetic findings of different forms of preaxial polydactyly is an important step in analysing and understanding the aetiology and pathogenesis of these limb malformations.

Results of the AO spinal internal fixator in the surgical treatment of thoracolumbar burst fractures.

The potential for clinical instability following thoracolumbar fractures has evoked a progressive increase in interest in the surgical treatment of unstable thoracolumbar fractures. From September 1988 to October 1991, 44 thoracolumbar burst fractures were treated surgically by the AO Spinal Internal Fixator at the Orthopaedics and Traumatology Clinics of Ankara Social Security Hospital. Mean follow-up period was 28.8 (range 12-48) months. Fourteen (31.8%) of the patients were female, and 30 (68.2%) were male. Postoperatively, the mean anterior vertebral height loss and spinal canal compromise were corrected by 36.5% and 39.9%, respectively. Also, postoperatively 15.9% of improvement was obtained in the mean kyphosis angle. The mean compression angle, which was 19.5 degrees preoperatively, was corrected by 12.3 degrees and came to an average of 7.1 degrees postoperatively. In light of these data, it is suggested that the AO Spinal Internal Fixator effectively restores three-dimensional alignment of the spine and provides a rigid fixation.

Cotrel-Dubousset instrumentation in the treatment of unstable thoracic and lumbar spine fractures.

The use of computed tomography and developments in spinal biomechanics have led to a better understanding of vertebral fractures. The disappointing results achieved with conservative treatment have led to an increasing popularity of surgical treatment in the last 15 years. The results of 20 unstable thoracic or lumbar spine fractures treated surgically with Cotrel-Dubousset instrumentation at the First Clinic of Orthopaedics and Traumatology of the Ankara Social Security Hospital between December 1988 and June 1991 were evaluated in this study. The mean follow-up was 31.9 months. The mean sagittal index angle was 23.7 degrees +/- 6.8 degrees preoperatively and was corrected by 67.1 +/- 29.9%, and the thoracolumbar junction angle was brought within physiological limits in 65% of the cases. Postoperatively, the neurological status improved in 15% of the patients and remained unchanged in the rest. It was concluded that the Cotrel-Dubousset instrumentation established vertebral stability in unstable vertebral fractures by forming a rigid frame and restored physiological thoracic and lumbar postural contours due to its highly corrective effect in the sagittal plane.

The computed tomographic evaluation of patellofemoral joint in patellar fractures treated with open reduction and internal fixation.

In this study, we examined 97 patella fractures in which open reduction and internal fixation had been performed at the 1st Orthopaedics and Trauma Clinic of Social Security Ankara Hospital between January 1983 and December 1988. After 24 to 96 months, on an average of 48.4 months follow-up period, the cases were evaluated clinically for knee function complaints and by CT and roentgenography for patellofemoral articulation. In 11 of the patients (11.5) there was patellar displacement, 2 of the patients had patellar tilt (2.1%) and in 14 patients (14.5%) there was malalignment in which 1 patient (1.1%) had both patellar tilt and displacement. This data was obtained by measuring femoral trochlear angle (FTA) and patellar tilt angle (PTA) by CT at various degrees of knee flexion. Thirty-three patients (34%) had slight and 19 patients (19.6%) had severe degenerative changes in the patellofemoral articulation. It is found that there is close relation between the variability of the pain complaints of the patients and the type of the fracture and the time of management and the postoperative rehabilitation.

Epidemiological, clinical and radiological aspects of osteopoikilosis.

Osteopoikilosis is a rare condition showing characteristic sclerotic lesions on radiographic examination, which are diagnostic for the trait. We report four patients presenting with various complaints and 49 members of their families who later were found to have osteopoikilosis. The mean age of all 53 was 27.5 years and the male:female ratio was 33:20. Most had lesions in the small tubular bones. We studied the epidemiological, clinical and radiological features of these patients and from the pedigrees conclude that the disease is inherited as an autosomal dominant.