Sex-related differences in the bone mineral density of atrophic mandibles

A case control study to investigate the effects of denture wear on residual alveolar ridge resorption in edentulous patients

OBJECTIVES

To investigate the effect of complete denture wearing on residual ridge resorption in edentulous patient compared with edentulous patient who never wore dentures.

METHODS

Patients who had been edentulous for at least five year who had never worn dentures successfully were matched to edentulous denture wearing control patients. To control for factors possibly associated with alveolar ridge resorption patients who had been rendered edentulous in one arch before the other, smokers, those taking steroids, bisphosphonates, with histories of autoimmune diseases, diabetes mellitus or osteoporosis at any time during their period of edentulousness were excluded. Case and control groups were matched for age, sex and time since being rendered edentulous. Statistical analyses were undertaken using Person's Chi squared (X²) test and Fisher's exact test.

RESULTS

30 edentulous patients who had not worn dentures for at least five years were identified and matched with 30 controls. All control patients were the same age ± 2 years and had been edentulous for the same number of years ± 2 years of their respective controls. There was no significant difference between age and time since being rendered edentulous between case and control. Denture wearers had significantly more maxillary and mandibular residual alveolar ridge resorption than did non denture wearers. Severe ridge resorption was mostly confined to the denture wearing group.

CONCLUSION

Patients wearing complete dentures for more than 5 years had significantly more residual alveolar ridge resorption than was found in non-denture wearing edentulous patients.

Association of Neutral Zone Position with Age, Gender, and Period of Edentulism

PURPOSE

The changing dynamics of an aging mouth influence the position of the neutral zone (NZ). While the advantage of the NZ concept in complete denture treatment is quite established, what is not clearly understood is its position in relation to the crest of the residual ridge due to conflicting reports from previous studies. The purpose of this study was to investigate the distance and direction of NZ position in relation to crest of the residual ridge in edentulous patients and its association with age, gender, and period of edentulism.

MATERIALS AND METHODS

A cross-sectional study was conducted in 133 patients (70 males, 63 females) with a mean age of 58.81 ± 11.78 years. NZ recording was done using admix material by following standard procedures. Two metallic wires were adapted, one on the ridge and another on the center of the occlusal rims, and standardized digital radiographs were made. The position of NZ in relation to the crest of the residual ridge was recorded by noting the direction and measuring the distance between the adapted wires digitally at five locations (right molar, right premolar, incisor, left molar, left premolar regions).

RESULTS

Age, gender, and period of edentulism had no significant association with the position of NZ. No specific trend was observed in the in NZ position with a non-significant correlation.

CONCLUSIONS

Distance and the direction of neutral zone position in relation to crest of the residual ridge in edentulous patients bear no significant relationship with factors such as age, gender, and period of edentulism.

Bone density and its importance in orthodontics

BACKGROUND

Researchers have generally focused on tissue reactions occurring within the periodontal ligament and bone to find possible explanation for various clinical phenomena, with less attention being paid to the inherent bone density. Recently, regional differences in jaw anatomy and bone structure including bone density have become important issue to explain some of the variation in clinical practice with respect to tooth movement, implant success rate, anchorage loss etc.

MATERIALS AND METHODS

The intent of this review is to discuss various methods and classification proposed to determine bone density in particular area and its importance in field of orthodontia. Various clinical studies and research done in relation to bone density were searched using PubMed.

RESULTS AND CONCLUSION

This review endeavours to compile the research of bone density in maxilla and mandible. Many clinical studies have demonstrated relation between bone density and various clinical phenomena in dentistry. Knowledge of bone density in particular area of oral cavity may help the clinician to plan proper site for implant placement and various anchorage augmentation techniques in order to increase success rate of the treatment.

Mandibular fracture in conjunction with bicortical penetration, using wide-diameter endosseous dental implants

Prosthodontic rehabilitation of a patient with an atrophic edentulous mandible presents a significant challenge in restoring esthetics and function. The purpose of this clinical report is to describe fracture of an atrophic edentulous mandible opposing maxillary natural dentition in association with endosseous dental implants. The patient received two wide-diameter implants in the anterior mandible for an implant-assisted mandibular overdenture, in which the implants penetrated the inferior border of the mandible for bicortical stabilization. Three months following implant placement surgery, the patient experienced pain, swelling, and intraoral purulent drainage around the right implant. Panoramic radiograph revealed a fracture of the mandible through the right implant site and signs of infection around the left implant. The implants were removed surgically, and open reduction and fixation of the fracture site were undertaken using a titanium bone fixation plate. This clinical report demonstrates that placement of wide-diameter implants in conjunction with bicortical penetration in a severely atrophic edentulous mandible can risk fracture of the mandible.

Sex differences in denture satisfaction

OBJECTIVES

Males and females differ in their responses to many health conditions and treatments. The aim of this randomized clinical trial was to determine whether there are differences in the way that male and female edentulous elders rate their satisfaction with new mandibular implant overdentures (IODs) and conventional dentures (CDs), at 6 and 12 months following delivery.

METHODS

Edentulous elders (n=256) were randomly assigned to receive maxillary conventional dentures and either mandibular overdentures supported by two implants with ball attachments or conventional dentures. Participants rated their general satisfaction, as well as other features of their dentures (comfort, stability, ability to chew, aesthetics, etc.) prior to treatment and 6 and 12 months after delivery.

RESULTS

Ratings of satisfaction with IODs were significantly higher than with CDs. Six months after delivery, females in the CD group rated their general satisfaction and satisfaction with ability to chew and aesthetics significantly lower than did the males. The sex differences in the CD group remained at 12 months after delivery. However, males and females in the IOD group rated their general satisfaction and all six subcategories equally.

CONCLUSIONS

Elderly females are less satisfied with conventional dentures than elderly males with regards to aesthetics and ability to chew, but equally satisfied with implant overdentures. At 6 and 12 months after delivery, elderly edentulous males and females wearing mandibular implant overdentures were significantly more satisfied than those wearing conventional dentures.

Oral implications of osteoporosis

OBJECTIVES

The association between osteoporosis and oral health remains a matter of controversy. It is important to confirm whether there is a role of osteoporosis in bone loss in the jaws, periodontal diseases, tooth loss, and other oral tissue changes. The objective of this article is to review and summarize the published literature on the associations between osteoporosis and various oral conditions such as bone loss in the jaws, periodontal diseases, and tooth loss.

METHODS

A search of the computerized database MEDLINE was conducted. Clinical information concerning systemic osteoporosis and animal studies reporting possible associations between osteoporosis and changes in the dental and oral tissues were included. The review focus was on studies involving (1) methods for assessing bone mineral density (BMD); (2) methods for assessing osteoporosis-related changes in intraoral sites; (3) associations between mandibular BMD and skeletal BMD; (4) changes in the jaws, periodontal tissues, and temporomandibular joint concurrent with osteoporosis; (5) changes in the oral tissues following estrogen deficiency; and (6) effects of estrogen-hormone replacement therapy and/or calcium and vitamin D on oral health.

RESULTS

Ninety-seven studies conducted in various parts of the world were identified. Evidence from prospective studies supports the contention that individuals with osteoporosis may be at increased risk for the manifestations of oral osteoporosis; however, such risk is not definitively proven. Studies suggest that findings on dental panoramic radiographs may be used to detect individuals with low BMD.

CONCLUSIONS

Further well-controlled studies are needed to better elucidate the inter-relationship between systemic and oral bone loss and to clarify whether dentists could usefully provide early warning for osteoporosis risk.

The three-dimensional microstructure of the trabecular bone in the mandible

This study investigated the three dimensional (3D) trabecular microstructure of the alveolar and basal bone in the mandible using micro-CT and compared the morphometric values of the different sites. Ten specimens were prepared and scanned using a micro-CT system. Both the alveolar and basal trabecular bone of the premolar region in the mandible were measured for the structural analysis. Cross-sectional 1024x1024 pixel images were created. From the two-dimensional (2D) images produced, 3D structural images were reconstructed. After scanning the specimen, the volumes of interest (VOI) of the alveolar and basal bone regions were selected from the 3D reconstruction images, and the structural parameters such as bone volume fraction, bone surface density, trabecular thickness, trabecular separation, trabecular number and structural model index were analyzed. The trabecular structure showed a marked variation within the sites of the specimen, especially in the basal trabecular bone inferior to the mandibular canal. In both the alveolar and basal bone regions, a mixture of both plate-like and rod-like structures was observed. The alveolar region showed a more compact, plate-type trabecular structure than the basal regions. In parametric comparison with the basal bone, the alveolar bone generally had a higher bone volume fraction, bone trabecular thickness and trabecular number, and lower bone surface density, trabecular separation and structural model index. The alveolar bone consisted of a compact bone structure with a large amount of thick plate-type trabecular bone, which was effectively resistant to the masticatory forces. As the measurements were made closer to the basal bone, a loose structure was observed with lower bone volume and fewer, thin, rod-like trabeculae.

Densitometric study of human developing dry bones: a review

In this article we describe the use of dual-energy X-ray absorptiometry (DXA) technique in the study of fetal and infant bone development. In particular, we review the results of densitometric studies on human developing dry bones such as spine, femur, and mandible; these data are compared with the results obtained with other methods used in the past. In particular DXA technique applied in dry is able to detect the first appearances of the ossification centers; show individual variability of bone mineral density yet during the prenatal life; and determine the correlation between bone mineral density and the variation of mechanical loading.

Periodontal diseases and osteoporosis: association and mechanisms

There is increasing evidence that osteoporosis, and the underlying loss of bone mass characteristic of this disease, is associated with periodontal disease and tooth loss. Periodontitis has long been defined as an infection-mediated destruction of the alveolar bone and soft tissue attachment to the tooth, responsible for most tooth loss in adult populations. Current evidence including several prospective studies supports an association of osteoporosis with the onset and progression of periodontal disease in humans. The majority of studies have shown low bone mass to be independently associated with loss of alveolar crestal height and tooth loss. However studies that focus on the relation of clinical attachment loss and osteoporosis are less consistent. To date, the majority of studies on the relationship between periodontal disease and osteoporosis have been hindered by small sample sizes, limited control of other potential confounding factors, varying definitions of both periodontal disease and osteoporosis, and few prospective studies where the temporality of the association can be established. Potential mechanisms by which host factors may influence onset and progression of periodontal disease directly or indirectly include underlying low bone density in the oral cavity, bone loss as an inflammatory response to infection, genetic susceptibility, and shared exposure to risk factors. Systemic loss of bone density in osteoporosis, including that of the oral cavity, may provide a host system that is increasingly susceptible to infectious destruction of periodontal tissue. Studies have provided evidence that hormones, heredity, and other host factors influence periodontal disease incidence and severity. Both periodontal disease and osteoporosis are serious public-health concerns in the United States. Prevalence of both osteoporosis and tooth loss increase with advancing age in both women and men. Understanding the association between these common diseases and the mechanisms underlying those associations will aid health professionals to provide improved means to prevent, diagnose, and treat these very common diseases. This paper reviews the current evidence on the association between periodontal disease and osteoporosis.

Differences in static cortical bone remodeling parameters in human mandible and iliac crest

Knowledge of the baseline turnover characteristics, and of possible general and local factors influencing alveolar bone responses, is particularly important in the planning of oral rehabilitation. The conventional tool used to obtain information on bone turnover is the iliac crest biopsy, but it is not clear whether it mirrors the situation involving the jaws. The aim of this study was to compare static bone remodeling parameters in the mandible and in the iliac crest to obtain baseline values for the mandible and to test the hypothesis of site specificity of bone remodeling. Bone specimens were obtained from 50 subjects (mean age 64 +/- 17) at autopsy. Three sites were sampled: iliac crest; jaw angle; and foramen mentalis area. In addition, occlusal status was recorded. On undecalcified thin sections, cortical porosity (Ct.Po), eroded sites (ESi), formative sites (FSi), osteonal diameter (On.Dm), Haversian canal diameter (H.Ca.Dm), and wall width (W.Wi) were measured. Ct.Po in the jaw angle and in the foramen mentalis area was lower (48% and 50%, respectively) than in the iliac crest, as was ESi and FSi (80% in the jaw angle and 74% in the foramen mentalis area). In the foramen mentalis area, Ct.Po was greater in subjects with occlusion. On.Dm, H.Ca.Dm, and W.Wi were significantly larger and mutually correlated within the mandible, whereas no correlation was found between mandibular sites and iliac crest. Static cortical bone remodeling parameters are different in the mandible and the iliac crest, thus confirming the hypothesis of site specificity of bone remodeling. Within the mandible, the parameters were correlated, whereas there was no correlation between the mandible and the iliac crest. This could be ascribed to the different functional demands to the mandible and the iliac crest, which was also reflected in the observed influence of functional occlusion on bone remodeling in the mandible. It can thus be concluded that bone reaction to dental intervention is more dependent on the local environment than on general bone turnover as reflected by the iliac crest.

The role of osteopenia in oral bone loss and periodontal disease

Osteoporosis and periodontitis are diseases which affect a large number of women and men, with incidence increasing with advancing age. Osteopenia is a reduction in bone mass due to an imbalance between bone resorption and formation, favoring resorption, resulting in demineralization and leading to osteoporosis. Osteoporosis is a disease characterized by low bone mass and fragility and a consequent increase in fracture risk. Periodontitis is characterized by inflammation of the supporting tissues of the teeth, resulting in resorption of the alveolar bone as well as loss of the soft tissue attachment to the tooth and is a major cause of tooth loss and edentulousness in adults. The relationship of osteopenia to oral bone loss and periodontal disease has been addressed in a limited number of studies. A review of current knowledge regarding this relationship is presented. Interpretation of the literature is complicated by the variety of methods used to assess osteopenia, oral bone mass, and periodontitis, as well as varying definitions of outcomes of interest. Results of a previously unpublished study are presented which suggest that severity of osteopenia is related to loss of alveolar crestal height and tooth loss in post-menopausal women. The literature on the relationship among these disorders is limited and points to the need for additional studies which thoroughly evaluate the influence of potential confounding factors to further define the relationship between low bone mineral density and periodontal disease in larger populations. Clearer understanding of this relationship may aid health care providers in their efforts to detect and prevent osteoporosis and periodontal disease. Increased dialogue among medical and dental professional will be increasingly important in achieving and maintaining patients' optimal health.

Quantitative computed tomography of trabecular bone in the mandible

OBJECTIVE

To evaluate the potential use of quantitative computed tomography (QCT) for the assessment of bone mineral density of the edentulous mandible prior to implant placement.

METHODS

Ten 2 mm thick CT slices of anterior and posterior edentulous sections from 15 mandibles were obtained perpendicular to the buccal and lingual plates. The bone mineral density, expressed as the amount of calcium hydroxyapatite (mg cm-3) of the trabecular bone, was calculated using a method that takes into account the influence of fat.

RESULTS

The variation of bone mineral density between mandibles was high. Anterior sections showed higher values than posterior sections and a variation was found within sections of the same mandible.

CONCLUSION

CT provides a site-related measure of the bone mineral density in the mandible and appears potentially useful as a non-invasive method to determine a parameter that may reflect bone quality prior to implant placement.