Correlation between upper airway dimension and TMJ position in patients with sleep disordered breathing.

OBJECTIVE: The goal was to perform a 10-year retrospective study on the correlation between sleep disordered breathing (SDB) and upper airway dimensions, as well as the relation between SDB status and TMJ position. The study also examined links between airway dimensions and TMJ position. METHODS: Patients were categorized into Control (n = 28) or SDB (n = 45). Cone beam (CBCT) data was analyzed using InVivo5™. RESULTS: Although there were distinctive features within the SDB group, these did not show a correlation of significance with airway dimensions. SDB patients were more likely to have their condyles posteriorly seated. Other factors, such as presence of TMD, limited mouth opening, and pain upon palpation of masticatory muscles also significantly affected the TMJ position. Volumetric airway analysis showed links to TMJ position. CONCLUSION: SDB patients have a smaller airway volume and have a significant relationship between airway volume and TMJ position with their condyles seated more posteriorly.

Effects of deformation twinning on the mechanical properties of biodegradable Zn-Mg alloys.

To satisfy the property requirements for biodegradable medical implants, Zn alloyed with low levels of Mg (≤0.8 wt%) has attracted increased research interest. In the present study, deformation twinning was observed in tensile tests and twinning appears to have an adverse impact on ductility. The profuse twinning in the as-cast Zn-Mg alloys accelerated crack growth in tension due to twinning impingement which caused local stress concentrations and initiates cracking. As-rolled Zn-Mg alloys have better ductility than their as-cast counterparts due to the inhibition of twinning by the refined Mg2Zn11 intermetallic phase and the finer grain size.

Evaluation of the first maxillary molar post-extraction socket as a model for dental implant osseointegration research.

OBJECTIVES: Published information regarding the use of rat jawbones for dental implant osseointegration research is limited and often inconsistent. This study assessed the suitability and feasibility of placing dental implants into the rat maxilla and to establish parameters to be used for dental implant research using this model. MATERIALS AND METHODS: Forty-two customized titanium implants (2 × 3 mm) were placed bilaterally in the maxillary first molar area of 21 Sprague-Dawley rats. Every animal received two implants. The animals were subsequently sacrificed at days 3, 7, 14, 28 and 56 post-surgery. Resin-embedded sections of the implant and surrounding maxilla were prepared for histological and histomorphometric analyses. RESULTS: The mesial root of the first molar in the rat maxilla was the optimal site to place the implant. Although the most apical 2-3 threads of the implant penetrated into the sinus cavity, 2 mm of the remaining implant was embedded in the bone. New bone formation at day 7 around the implant increased further at day 14, as measured by the percentage of bone-to-implant contact (%BIC) and new bone area (%BA) in the implant thread chambers (55.1 ± 8.9% and 63.7 ± 7.7%, respectively). There was a further significant increase between day 14 and 28 (P < 0.05), however, no significant differences were found between day 28 and 56 in either %BIC or %BA. CONCLUSIONS: The mesial root socket of the first molar in the rat maxilla is a useful model for dental implant research. Osseointegration following implant placement as measured by BIC plateaued after 28 days. The recommended implant dimensions are 1.5 mm in diameter and 2 mm in length.

Estrogen Deficiency-Associated Bone Loss in the Maxilla: A Methodology to Quantify the Changes in the Maxillary Intra-radicular Alveolar Bone in an Ovariectomized Rat Osteoporosis Model.

The effects of estrogen deficiency on bone characteristics are site-dependent, with the most commonly studied sites being appendicular long bones (proximal femur and tibia) and axial bones (vertebra). The effect on the maxillary and mandibular bones is still inconsistent and requires further investigation. This study was designed to evaluate bone quality in the posterior maxilla of ovariectomized rats to validate this site as an appropriate model to study the effect of osteoporotic changes. Forty-eight 3-month-old female Sprague-Dawley rats were randomly divided into two groups: an ovariectomized (OVX) group (n=24) and Sham-operated (SHAM) group (n=24). Six rats were randomly sacrificed from both groups at time points 8, 12, 16, and 20 weeks. The samples from tibia and maxilla were collected for micro computed tomography (µCT) and histological analysis. For the maxilla, the volume of interest area focused on the furcation areas of the first and second molar. Trabecular bone volume fraction (BV/TV, %), trabecular thickness (Tb.Th.), trabecular number (Tb.N.), trabecular separation (Tb.Sp.), and connectivity density (Conn.Dens) were analyzed after Micro CT scanning. At 8 weeks the indices BV/TV, Tb.Sp., Tb.N., and Conn.Dens showed significant differences (p<0.05) between the OVX and SHAM groups in the tibia. Compared with the tibia, the maxilla developed osteoporosis at a later stage, with significant changes in maxillary bone density only occurring after 12 weeks. Compared with the SHAM group, both the first and second molars of the OVX group showed significantly decreased BV/TV values from 12 weeks, and these changes were sustained through 16 and 20 weeks. For Tb.Sp., there were significant increases in bone values for the OVX group compared with the SHAM group at 12, 16, and 20 weeks. Histological changes were highly consistent with Micro CT results. This study established a method to quantify the changes of intra-radicular alveolar bone in the posterior maxilla in an accepted rat osteoporosis model. The degree of the osteoporotic changes to trabecular bone architecture is site-dependent and at least 3 months are required for the osteoporotic effects to be apparent in the posterior maxilla following rat OVX.

Flapless dental implant surgery: a retrospective study of 1,241 consecutive implants.

PURPOSE: The purpose of this study was to identify retrospectively the predictors of implant survival when the flapless protocol was used in two private dental practices. MATERIALS AND METHODS: The collected data were initially computer searched to identify the patients; later, a hand search of patient records was carried out to identify all flapless implants consecutively inserted over the last 10 years. The demographic information gathered on statistical predictors included age, sex, periodontal and peri-implantitis status, smoking, details of implants inserted, implant locations, placement time after extraction, use of simultaneous guided hard and soft tissue regeneration procedures, loading protocols, type of prosthesis, and treatment outcomes (implant survival and complications). Excluded were any implants that required flaps or simultaneous guided hard and soft tissue regeneration procedures, and implants narrower than 3.25 mm. RESULTS: A total of 1,241 implants had been placed in 472 patients. Life table analysis indicated cumulative 5-year and 10-year implant survival rates of 97.9% and 96.5%, respectively. Most of the failed implants occurred in the posterior maxilla (54%) in type 4 bone (74.0%), and 55.0% of failed implants had been placed in smokers. CONCLUSION: Flapless dental implant surgery can yield an implant survival rate comparable to that reported in other studies using traditional flap techniques.

Serum bone formation marker correlation with improved osseointegration in osteoporotic rats treated with simvastatin.

OBJECTIVE: Simvastatin has been shown to enhance osseointegration of pure titanium implants in osteoporotic rats. This study aimed to evaluate the relationship between the serum level of bone formation markers and the osseointegration of pure titanium implants in osteoporotic rats treated with simvastatin. MATERIALS AND METHODS: Fifty-four female Sprague-Dawley rats, aged 3 months, were randomly divided into three groups: Sham-operated group (SHAM; n = 18), ovariectomized group (OVX; n = 18), and ovariectomized with simvastatin treatment group (OVX + SIM; n = 18). Fifty-six days after ovariectomy, screw-shaped titanium implants were inserted into the tibiae. Simvastatin was administered orally at 5 mg/kg each day after the placement of the implant in the OVX + SIM group. The animals were killed at either 28 or 84 days after implantation and the undecalcified tissue sections were processed for histological analysis. Total alkaline phosphatase (ALP), bone-specific alkaline phosphatase (BALP) and bone Gla protein (BGP) were measured in all animal sera collected at the time of euthanasia and correlated with the histological assessment of osseointegration. RESULTS: The level of ALP in the OVX group was higher than the SHAM group at day 28, with no differences between the three groups at day 84. The level of BALP in the OVX + SIM group was significantly higher than both OVX and SHAM groups at days 28. Compared with day 28, the BALP level of all three groups showed a significant decrease at day 84. There were no significant differences in BGP levels between the three groups at day 28, but at day 84, the OVX + SIM group showed significantly higher levels than both the OVX and SHAM groups. There was a significant increase in BGP levels between days 28 and 84 in the OVX + SIM group. The serum bone marker levels correlated with the histological assessment showing reduced osseointegration in the OVX compared to the SHAM group which is subsequently reversed in the OVX + SIM group. CONCLUSION: The results from this study indicate that the serum level of bone formation markers, especially BALP and BGP, could be correlated with the degree of osseointegration around titanium implants in osteoporotic rats treated with simvastatin.

Application of autologous periosteal cells for the regeneration of class III furcation defects in Beagle dogs.

The aim of this study was to evaluate the healing of class III furcation defects following transplantation of autogenous periosteal cells combined with beta-tricalcium phosphate (beta-TCP). Periosteal cells obtained from Beagle dogs' periosteum explant cultures, were inoculated onto the surface of beta-TCP. Class III furcation defects were created in the mandibular premolars. Three experimental groups were used to test the defects' healing: group A, beta-TCP seeded with periosteal cells were transplanted into the defects; group B, beta-TCP alone was used for defect filling; and group C, the defect was without filling materials. Twelve weeks post surgery, the tissue samples were collected for histology, immunohistology and X-ray examination. It was found that both the length of newly formed periodontal ligament and the area of newly formed alveolar bone in group A, were significantly increased compared with both group B and C. Furthermore, both the proportion of newly formed periodontal ligament and newly formed alveolar bone in group A were much higher than those of group B and C. The quantity of cementum and its percentage in the defects (group A) were also significantly higher than those of group C. These results indicate that autogenous periosteal cells combined with beta-TCP application can improve periodontal tissue regeneration in class III furcation defects.