A Comprehensive Clinical Review of Maxillary Sinus Floor Elevation in Patients with Well-Defined Faintly Radiopaque Lesions in the Antrum.

Well-defined, faintly radiopaque lesions are occasionally observed in the antrum of the maxillary sinus in asymptomatic patients during maxillary sinus floor elevation. These lesions are treated as antral pseudocysts (AP) based on the clinical diagnosis in some cases, and maxillary sinus floor elevation is performed without enucleating these lesions. However, further surgery is required after implant placement if the lesion is a mucocele, odontogenic cyst, or tumour. This comprehensive clinical review aimed to identify an appropriate approach for maxillary sinus floor elevation in patients with well-defined, faintly radiopaque lesions in the antrum based on our clinical experience.

A Reliable Surgical Procedure for Sinus Floor Augmentation with Antral Pseudocysts.

An antral pseudocyst (AP) is a common well-defined 'dome-shaped' faintly radiopaque lesion of the maxillary sinus, and usually does not require treatment in asymptomatic patients. However, when sinus floor augmentation is required to increase bone volume for implant installation, the elevation of the sinus mucosa might drive the AP against the ostium. This might cause its obstruction and, as possible consequence, sinusitis. The purpose of this study was to investigate the clinical and tomographic conditions of APs to identify a predictable cyst removal that might allow a safety sinus floor augmentation. A total of 52 maxillary sinuses in 46 patients (mean age 55.1 years) presenting AP were examined by cone beam computed tomographies (CBCTs). A two-stage approach was applied. At the first surgery, the cystic lesions were further inspected by an endoscope through the antrostomy, and histopathological diagnosis of the removed tissues was carried out. After the confirmation of decrease of the swelling of sinus membrane by CBCT, the sinus floor augmentation was performed, at least four months after cyst removal. The color and transparency of the 86 cystic lesions were classified into 4 types. The whitish transparent cysts were 34 (39.5%), the yellowish transparent cysts were 18 (20.9%), the dark purple transparent cysts were 8 (9.3%) and the milky-white opaque cysts were 26 (30.2%). The contents of the 60 (69.8%) transparent cysts were serous fluid, but those of milky-white cysts were composed of viscous or elastic soft tissues, and the aspiration of the contents was unsuccessful. The analysis of the preoperative CBCT did not provide certainty on the contents of the cystic lesions. All cystic lesions were diagnosed as AP, and an infection was identified in one AP, presenting marked infiltration of the inflammatory cells. Considering the difficulties of performing a correct diagnosis of the AP content by a CBCT analysis, the risk of failure of the surgery that creates severe afflictions to the patients, and the necessity of a histological evaluation of the cyst, a two-stage surgery appeared to be the most reliable procedure.

Horizontal alveolar ridge distraction osteogenesis in dogs: radiographic and histologic studies.

PURPOSE: This study was designed to evaluate the healing process in horizontal alveolar ridge distraction of the narrow alveolus in dogs. MATERIALS AND METHODS: Six beagle dogs weighing approximately 9 to 10 kg were used in this experiment. Horizontal alveolar ridge distraction was performed in the right mandible, where the premolars had been extracted 12 weeks previously. Twelve days after the completion of distraction, the lengthening apparatus was removed. The distracted site was evaluated at 12 and 24 weeks after the removal. RESULTS: At 12 weeks, thin woven bone was observed at the distracted site growing from the surface of the original lingual cortical bone toward the transport segment. At 24 weeks, the distracted site had fully changed into new mature lamellar bone, but the transport segments had been almost completely resorbed. DISCUSSION: Horizontal alveolar ridge distraction was performed successfully in beagle dogs even though the apparatus was removed 12 days after the completion of distraction. The most important feature of this technique is the resorption of the transport segment. CONCLUSION: Horizontal alveolar ridge distraction can be a beneficial technique for augmenting the alveolar ridge horizontally in the buccolingually reduced alveolar process before the placement of implants.

Vitamin D receptor gene polymorphism is associated with chronic periodontitis.

Chronic periodontitis (CP) is caused by enhanced resorption of the alveolar bone supporting the teeth and is associated with intraoral inflammation after infection with certain bacteria. The VDR gene polymorphism was reported recently to be deeply related to the occurrence of tuberculosis and infection of chronic hepatitis B virus. This may be interpreted to indicate a close relationship between VDR gene polymorphism and the immunological action, because vitamin D activates monocytes, stimulates cell-mediated immunity, and suppresses lymphocyte proliferation. The purpose of the present study was to clarify whether polymorphisms in VDR gene exons are associated with the incidence of CP. A case-controlled study was performed on a group of 168 unrelated Japanese subjects whose ages ranged from 35 to 65 years. The Taq I polymorphism in the VDR gene was found to be associated significantly with CP (X2=4.48, P=0.034). We performed multiple logistic regression analyses on the TT genotype, which was found to be associated with CP, and on well-recognized risk factors, smoking and diabetes. The odds ratio (OR) for the genotype (TT/Tt) was 2.73 (95% CI 1.11-6.68, P=0.028), being larger than the unadjusted value. This indicates that the VDR gene polymorphism (TT genotype) is a risk factor for CP, independently of smoking and diabetes.

Bone morphogenetic protein-4 gene polymorphism and early marginal bone loss around endosseous implants.

PURPOSE: At stage II surgery during dental implant treatment, early marginal bone loss around the implant occasionally occurs despite a lack of apparent causal events, and the etiology of this bone loss is unclear. This study was designed to investigate whether the bone morphogenetic protein-4 (BMP-4) genetic polymorphism is associated with early marginal bone loss around implants. MATERIALS AND METHODS: The BMP-4 polymorphism was detected by restriction fragment length analysis using HphI digestion after polymerase chain reaction. A total of 262 implants were placed in 41 patients, and early marginal bone loss was observed in 25 of the 109 maxillary implants and 14 of the 153 mandibular implants. RESULTS: In the mandible, the patients with the BMP-4 AV genotype had a significantly higher rate of occurrence of marginal bone loss than those with the BMP-4 W genotype (P = .012). According to multiple logistic regression analyses, the odds ratio of the AV versus the W BMP-4 genotype was 8.106 between patients with and those without bone loss in the mandible (95% CI = 1.30 to 50.51; P = .025). DISCUSSION: These results suggest that the BMP-4 genetic polymorphism influences early marginal bone loss around implants. CONCLUSION: While perhaps premature in recommendation, genetic screening before implant surgery may prove to be a very useful aid to consider the risk of implant treatment.

Genetic polymorphisms of the interleukin-1 gene and early marginal bone loss around endosseous dental implants.

Dental implant surgery commonly proceeds in two stages. It is generally accepted that bone loss around implants does not occur at stage-II surgery because implants do not receive mechanical loading. However, early marginal bone loss around implants occasionally does occur during the healing period. Genetic polymorphisms in the interleukin-1 (IL-1) gene have been reported to be important for bone homeostasis and susceptibility to bone disease. We therefore investigated whether the idiopathic early marginal bone loss around implants is related to polymorphisms in the IL-1 gene. We performed a case-control study. Patients demonstrating marginal bone loss around implants at stage-II surgery were designated as the 'marginal bone loss (+)' group and those without bone loss as the 'marginal bone loss (-)' group. Polymorphisms of the IL-1alpha and IL-1beta genes (IL-1A-889, IL-1B-511 and IL-1B+3954) were detected by restriction fragment length polymorphism using NcoI, AvaI and TaqI after polymerase chain reactions. A total of 251 implants were placed in 39 patients. Marginal bone loss was observed in 36 implants. The patients with IL-1B-511 2/2 genotype exhibited a significantly higher occurrence of marginal bone loss than those with IL-1B-511 1/1 or 1/2 genotypes (OR=5.63; 95% CI=1.20-26.42; P=0.033). Multiple logistic regression analyses showed a markedly increased odds ratio (OR=10.86; 95% CI=1.64-71.90) in IL-1B-511 2/2 genotype carriers, while ORs of the other risk factors for bone loss, such as age, smoking status, post-menopausal women and bone quality, remained between 0.44 and 6.20. There was no significant difference in the distributions of the IL-1B+3954 and IL-1 A-889 genotypes between cases and controls. These data suggest that the IL-1B-511 2/2 genotype has a significant association with the incidence of early marginal bone loss around endosseous implants.

Association of calcitonin receptor gene polymorphism with early marginal bone loss around endosseous implants.

PURPOSE: This study investigated the relationship between calcitonin receptor (CTR) genotype and buccal marginal bone loss observed at stage II surgery for endosseous implants. MATERIALS AND METHODS: A total of 237 implants were placed in 35 patients; 89 implants were placed in maxillae and 148 implants in mandibles. The CTR genetic polymorphism was examined by the polymerase chain reaction restriction fragment length polymorphism method. RESULTS: Patients with the TC genotype were 20 times more likely to suffer buccal marginal bone loss in the mandible than patients with the CC genotype. Furthermore, there were no significant differences in the distribution of age, smoking status, postmenopausal women, and bone quality between patients with and without bone loss in either jaw. DISCUSSION: These results suggest that the known risk factor for bone loss cannot explain the early marginal bone loss around the implants. CONCLUSION: Although further genetic research should be conducted, it is suggested that the CTR genetic test could become a useful tool in the planning of treatment before implant surgery and lead to more predictable implant treatment.

Endosseous implants in horizontal alveolar ridge distraction osteogenesis.

PURPOSE: This study evaluated horizontal distraction of the narrow alveolar ridge in dogs and the possibility of achieving osseointegration of implants placed into the distracted site during a consolidation period. MATERIALS AND METHODS: Six beagle dogs weighing approximately 9 to 10 kg were used in this experiment. Twelve weeks after extraction of the mandibular premolars, horizontal alveolar ridge distraction was performed using an originally designed lengthening apparatus. Twelve days after the completion of distraction, screw-type implants were placed into the distracted site. RESULTS: Twelve weeks after the placement of implants, thin lamellar bone rose horizontally from the transport segment toward the surface of the implant. Twenty-four weeks after their placement, the implants were fully embedded in mature lamellar bone, and direct bone contact with the implant surface could be seen. DISCUSSION: Horizontal alveolar ridge distraction was performed successfully by using a lengthening apparatus in the narrow alveolar models. Osseointegration was achieved even though the implants were placed into the distracted site during the consolidation period. CONCLUSION: Horizontal alveolar ridge distraction can be a beneficial technique in the placement of implants In the narrow alveolar ridge in the dog population.