Gabriella Dvorak

Peri‐implantitis and late implant failures in postmenopausal women: a cross‐sectional study

AIM Systemic bone loss is a major cause of fractures in postmenopausal women and may also affect the jawbone; however, its consequences on the success of dental implants remain poorly understood. MATERIALS AND METHODS In this cross-sectional study, the relation between self-reported osteoporosis and the success rate of dental implants in an adult female population was evaluated. The primary outcome parameters were the occurrence of peri-implantitis and late implant failures. Women with unknown bone status were excluded from the study. The potential confounders age, recipient site, smoking, periodontal disease and time of loading were recorded. RESULTS Data from 203 women with a mean age of 63 ± 9 years and 967 dental implants were investigated. The patients were classified according to their medical history into one of three groups: osteoporosis (47 women), osteopenia (16 women) and healthy controls (140 women). Patients with unknown bone status (n=26) were excluded. The multi-level statistical analysis showed no association between peri-implantitis [odds ratio (OR) 2.1; p=0.6] or implant failure [hazards ratio (HR) 2.5; p=0.2] and systemic bone loss. CONCLUSIONS No relation was found between osteoporosis and peri-implantitis in an adult female population.

Impact of dietary vitamin D on osseointegration in the ovariectomized rat

AIM Vitamin D deficiency is highly prevalent in the population and associated with impaired peri-implant bone regeneration. Yet, there is a gap in understanding the impact of vitamin D supplementation on the process of osseointegration. In this study, the effect of vitamin D supplementation on peri-implant bone regeneration was investigated. METHODS Fifty ovariectomized Sprague-Dawley rats were divided into three groups. The depletion group was fed a vitamin D-free diet for 8 weeks. The repletion group received vitamin D-free diet for 6 weeks, before animals were switched to standard diet containing 2400 IU/kg vitamin D. The control group was fed the standard diet. Two titanium mini-implants were placed in the tibia. All groups remained on their previous diet until sacrifice. Blood sample testing and histomorphometric analysis were performed. RESULTS Vitamin D depletion caused a significant reduction in 25-hydroxvitamin D in rat serum that returned to control levels in the repletion group. This vitamin deficiency was associated with a decrease in bone-to-implant contact in the cortical area, which was leveled to controls in the repletion group. No significant changes by vitamin D depletion were noticed in the medullar compartment. Moreover, also the peri-implant bone area and the mineral apposition rate remained unchanged upon vitamin D depletion. CONCLUSION These results indicate that vitamin D deficiency has a negative impact on cortical peri-implant bone formation in ovariectomized rats, which can be compensated by vitamin D supplementation. This study provides first insight into the potential beneficial effect of vitamin D supplementation in implant dentistry.

Effect of Maxillary Sinus Floor Augmentation on Sinus Membrane Thickness in Computed Tomography

BACKGROUND Little is known about maxillary sinus compliance, i.e., the intrinsic potential of the sinus membrane to resume its homeostatic status after the surgical trauma caused by sinus floor elevation. The aim of the present study is to investigate the effect of maxillary sinus floor augmentation on sinus membrane thickness. METHODS Within-patient comparison of computed tomographic scans before bone grafting versus 4 to 6 months after bone grafting was performed. Changes in membrane thickness were evaluated in 65 maxillary sinus floor augmentation procedures via a lateral approach in 35 patients without clinical signs of sinus pathology at any time. RESULTS Sinus membrane thickness differed significantly before (0.8 ± 1.2 mm) versus after (1.5 ± 1.3 mm) augmentation surgery (P <0.001), with a mean increase of 0.8 ± 1.6 mm (maximum: 4.4 mm). Only 28% of augmented sinuses did not show membrane thickening. In non-augmented control sinuses, there was no evidence of membrane thickness increase. CONCLUSIONS The results indicate that the maxillary sinus membrane, even in healthy clinical conditions, undergoes morphologic modifications after sinus floor elevation, yet membrane reactions demonstrate significant variability. Future research on the effect of augmentation surgery on maxillary sinus physiology is recommended.

The use of onplants and implants in children with severe oligodontia: a retrospective evaluation

OBJECTIVE To evaluate a stable treatment concept for the oral rehabilitation of children with severe oligodontia. The treatment is intended to solve a specific problem caused by limited skeletal growth, multiple congenital missing teeth, underdeveloped bone volume and young age. MATERIAL AND METHODS A surgical/prosthodontic approach was chosen for six patients with subtotal edentulism despite their young age. To support removable dentures the maxilla was treated with onplants (OnPlant), whereas dental rootform implants (NobelReplace, Nobel Biocare) were placed in the mandible. RESULTS Eight onplants were placed in the hard palate of four patients for rehabilitating the maxilla and eight dental rootform implants were placed interforaminally in three patients to rehabilitate the mandible. While none of the rootform implants was lost, one onplant was lost and replaced with a stable outcome. The mean follow-up time of the onplants was 5 (±1) years vs. 3 (±2) years for the rootform implants. CONCLUSION The evaluation showed the treatment concept described to ensure stable oral rehabilitation and recovery of the stomatognathic system even during the juvenile growth period.

Periodontal histomorphometry and status of aged sheep subjected to ovariectomy, malnutrition and glucocorticoid application.

OBJECTIVE Ageing, hypogonadism, malnutrition, and the application of glucocorticoids have adverse effects on skeletal homeostasis. Herein we determined to which extent the periodontium undergoes catabolic changes under these conditions in a sheep model. METHODS Six old sheep with a mean age of 7.5+/-1.0 years were subjected to ovariectomy, calcium/vitamin D-restricted diet, and intramuscular administration of approximately 2g methylprednisolone. Six adult sheep with a mean age of 3.8+/-0.9 years remained untreated and served as controls. First and second premolars of both jaws were subjected to histological analysis. The distances from the gingival margin (GM) and from the alveolar bone crest (ABC) to the cemento-enamel junction (CEJ) were determined. Periodontal attachment was given as the ratio between the dimension of the periodontal ligament and the alveolar bone. Clinical data were collected by counting the number of teeth missing, teeth with gingival recession, and teeth with a probing depth > 4 mm. RESULTS We report that distance between GM and CEJ (2.1+/-1.7 mm and 6.6+/-2.6mm maxilla; -0.4+/-1.4 mm and 3.2+/-1.5 mm mandible), and between ABC and CEJ (-3.4+/-1.3mm and 1.8+/-2.7 mm maxilla; -3.5+/-1.1mm and -0.1+/-1.4mm mandible) are significantly lower in test than in control animals. In line with these findings, periodontal attachment was 67% in the maxilla and 86% in the mandible of the test group and almost completely preserved in the control group. Clinical evaluation showed that the overall number of teeth with recessions was significantly higher in the test compared to the control group (4.9+/-2.4 and 2.3+/-3.6), but not the number of teeth missing and teeth with a probing depth>4mm. CONCLUSIONS Together these findings suggest that in sheep, the cumulating effects of ageing, hypogonadism, malnutrition and glucocorticoid application can cause substantial catabolic changes of the periodontium.

Cortical porosity of the mandible in an osteoporotic sheep model

OBJECTIVES Cortical porosity and thickness of the axial and the appendicular skeleton are predictors of osteoporotic fractures. In the jawbone, however, cortical porosity and thickness may affect the mechanical stability of dental implants. We have shown previously that the jawbone of osteoporotic sheep has impaired trabecular structures, but whether catabolic bone turnover also accounts for the cortical bone porosity remains unknown. MATERIAL AND METHODS We compared mandibular bone from six geriatric sheep subjected to ovariectomy, calcium/vitamin D restriction, and methylprednisolone administration to those of six healthy adult control sheep. Histological ground sections were prepared from the diastema, first and second premolars, and postmolar region. Cortical porosity and thickness were assessed by histomorphometry. RESULTS Cortical porosity was higher in osteoporotic sheep than in adult controls in the diastema and in the first and second premolar region. In the postmolar region, the difference failed to reach the level of significance. The changes were even more prominent when histomorphometry was restricted to the inner millimeter of the mandibular cortex. In contrast, induction of osteoporosis did not have a discernable effect on cortical thickness. CONCLUSION These results demonstrate that cortical porosity of mandibles is more pronounced in geriatric osteoporotic sheep than in adult controls.

Does osteoporosis influence the marginal peri‐implant bone level in female patients? A cross‐sectional study in a matched collective

BACKGROUND/PURPOSE Osteoporosis, being a homeostatic imbalance, affects the remodeling of bone. Whether this catabolic bone disease influences peri-implant marginal bone remodeling remains unknown so far. The purpose of this study was to evaluate the influence of osteoporosis on peri-implant marginal bone loss (MBL) in postmenopausal women. MATERIALS AND METHODS In a matched collective, radiographic peri-implant bone level (at baseline and at follow-up examinations) was compared in healthy and osteoporotic women. General health and behavioral history of the patients were recorded using a printed questionnaire. RESULTS A best fit matching procedure generated a sample of 48 women with a total of 204 implants matched at patient and implant level that was further statistically analyzed. The mean mesial MBL-statistically corrected to report the first year-was -0.6 ± 1.2 mm (range: -5.1 to 2.2) in the healthy control group and -1.1 ± 1.3 mm (range: -5.3 to 2.2) in the osteoporotic group. Similarly, the mean distal MBL was -0.5 ± 1.3 mm (range: -5.1 to 4.8) in the healthy control group and -1.2 ± 1.3 mm (range: -4.7 to 1.6) in the osteoporotic group, respectively. The base linear regression models including solely osteoporosis and time without any other confounders revealed a significant influence of osteoporosis and time since implant placement on the MBL at the mesial and the distal implant aspect. The significance of osteoporosis on bone loss did not change incorporating the confounders: bone level at implantation, smoking, jaw, location, surface, concrement, plaque, augmentation, edentulism in opposing and implant jaw, bisphosphonates, vitamin D, fixed versus removable prosthetics, connection type. CONCLUSIONS There is no contraindication to place dental implants in osteoporotic patients. This study implicates to respect the bone level at implant placement and not to place the implant below bone level if possible.

Dental implants are a viable alternative for compensating oligodontia in adolescents

OBJECTIVES To clinically and radiographically evaluate dental implant treatment in adolescents with extensive oligodontia. METHODS Patients with more than nine permanent teeth congenitally missing and implant treatment before the age of 16 years were included. Clinical follow-ups involved bleeding on probing, plaque index and peri-implant probing value. The peri-implant bone level was analysed on panoramic radiographs at time of implant treatment and at follow-up. Characteristics of the dental implants and patients were retrieved. RESULTS This study involved 18 patients (nine males, nine females) having 71 dental implants. The lower left premolar was predominantly missing. The mean age at the time of dental implant treatment was 12.5 (± 2.6) years. The bleeding on probing value was determined negative on 44%. The mean pocket depth was 3.6 (± 1.1) mm. The peri-implant bone level correlated significantly negative with the age at time of implant placement (r = -0.346, P = 0.004). The region of implant habits had no influence on peri-implant bone level. Dental implant treatment in adolescents resulted in a survival rate of 89% (63/71) and a mean loading time of 11.0 (± 4.1) years. The implant crowns to be renewed resulted in 54% (9 of 18 patients, 38 of 71 crowns) after a period of 7.8 ± 4.5 years. CONCLUSION Dental implant treatment in maturing adolescents with extensive oligodontia before is supported by the data of the present study. Providing that other treatment options are considered, the areas of skeletal growth are respected and the patients are well informed. To enhance quality of life of growing children with oligodontia clinicians are asked to evaluate their long-term outcome on dental implant treatment in adolescents.

Morphometric analysis of sinus depth in the posterior maxilla and proposal of a novel classification

The aim of this study was to analyse the posterior maxillary sinus based on its extension into the alveolar process and to provide a simple clinical classification. A retrospective cohort study was conducted in CT scans of 200 dentate and 200 edentulous patients (100 women and 100 men, respectively). After manual placement of 12 reference points morphometric analysis was performed and sinus depth, residual alveolar ridge height (RH) and the sinus opening angle were calculated. Sinuses were classified according to the quartiles of sinus depth: class I (above the hard palate), class II (0–6 mm below the hard palate) and class III (>6 mm below the hard palate). Sinus depth was found to be a reliable anatomical landmark and did not vary significantly between gender (p = 0.8940) or dentition groups (p = 0.9723). Alveolar height varied significantly between sinus classes (p < 2 × 10−16) and dentition groups (p < 2 × 10−16) but not between genders (p = 0.5178). The sinus opening angle was significantly different between sinus classes (p < 2.2 × 10−16) but not between gender or dentition groups. We propose a novel classification built upon the quartiles of sinus depth, dividing the sinuses into three classes. Our classification is the first one that represents the anatomy of the patient independent of gender and dentition.