Bones provide mechanical and protective function, while also serving as housing for marrow and a site for regulation of calcium ion homeostasis. The properties of bones do not remain constant with age; rather, they change throughout life, in some cases improving in function, but in others, function deteriorates. Here we review the modifications in the mechanical function and shape of bones, the bone cells, the matrix they produce, and the mineral that is deposited on this matrix, while presenting recent theories about the factors leading to these changes.

Aging and Bone

The diagnostic efficacies of three panoramic-based indices were compared with classification of bone mineral density by dual-energy x-ray absorptiometry. The panoramic indices were 1) cortical bone height, 2) an ordinal classification, and 3) the Panoramic Mandibular Index. The results indicate that panoramic dental radiographs should not be used to assess the patient's status regarding osteoporosis, although the means of the variables in different mineral density groups of skeleton may differ significantly.

Pantomography in assessment of the osteoporosis risk group.

Aims: To review the literature related to the analytical epidemiology of periodontitis generated over the past decade. This review does not deal with descriptive epidemiologic studies of the prevalence, extent and severity of periodontitis with respect to global geography, but focuses exclusively on analytical epidemiology issues, including the challenges posed by the use of different case definitions across studies, current theories and models of disease progression, and risk factors associated with the onset and progression of periodontitis.

Methods: Relevant publications in the English language were identified after Medline and PubMed database searches.

Findings and conclusions: There is a conspicuous lack of uniformity in the definition of periodontitis used in epidemiologic studies, and findings from different research groups are not readily interpretable. There is a lack of studies that specifically address the distinction between factors responsible for the onset of periodontitis versus those affecting its progression. Colonization by specific bacteria at high levels, smoking, and poorly controlled diabetes have been established as risk factors for periodontitis, while a number of putative factors, including specific gene polymorphisms, have been identified in association studies. There is a clear need for longitudinal prospective studies that address hypotheses emerging from the cross-sectional data and include established risk factors as covariates along with new exposures of interest. Intervention studies, fulfilling the “targeting” step of the risk assessment process, are particularly warranted. Obvious candidates in this context are studies of the efficacy of elimination of specific bacterial species and of smoking cessation interventions as an alternative to the traditional broad anti-plaque approach in the prevention and control of periodontitis. Ideally, such studies should have a randomized-controlled trial design.

Analytical epidemiology of periodontitis

Aim: The aim of this retrospective study was to assess the influence of systemic and local bone and intra-oral factors on the occurrence of early implant failures, i.e. up to the abutment connection.

Material and Methods: The surgical records of 2004 consecutive patients from the total patient population who had been treated in the period 1982–2003 (with a total of 6946 Branemark system® implants) at the Department of Periodontology of the Catholic University Leuven were evaluated. For each patient the medical history was carefully checked. Data collection and analysis mainly focused on endogenous factors such as hypertension, coagulation problems, osteoporosis, hypo-hyperthyroidy, chemotherapy, diabetes type I or II, Crohn's disease, some local factors [e.g. bone quality and quantity, implant (length, diameter, location), type of edentulism, Periotest® value at implant insertion, radiotherapy], smoking habits and breach of sterility during surgery.

Results: A global failure rate of 3.6% was recorded. Osteoporosis, Crohn's disease, smoking habits, implant (length, diameter and location) and vicinity with the natural dentition were all significantly associated with early implant failures (p<0.05).

Conclusion: The indication for the use of oral implants should sometimes be reconsidered when alternative prosthetic treatments are available in the presence of possibly interfering systemic or local factors.

Impact of local and systemic factors on the incidence of oral implant failures, up to abutment connection

Background: Systemic bone loss has been proposed as a risk factor for periodontal disease; however, the relationship between these two diseases is still not clear. The objective of this study was to assess the relationship between systemic bone mineral density and periodontal disease, controlling for known confounders. Methods: The study population included 70 postmenopausal Caucasian women aged 51 to 78 (mean ± SD: 62.10 ± 7.1 years). Skeletal bone mineral density (BMD) was assessed by dual energy x-ray absorptiometry (DXA) at the neck, trochanter, intertrochanter, Ward's triangle, and total regions of the femur, and from the anterior-posterior view of the lumbar spine. Periodontal disease severity was represented by clinical attachment loss (CAL) and interproximal alveolar bone loss (ABL). Other measures of periodontal status included probing depth (PD), supragingival plaque, gingival bleeding on probing, and calculus. DXA and oral examinations were performed by calibrated examiners. Partial correlation...

The relationship between bone mineral density and periodontitis in postmenopausal women.

Osteoporosis is suspected as a risk factor in periodontal disease, but previous studies have failed to establish a relationship. Possible explanations for this could be lack of precise methods for assessment of osteoporosis in the jaws and confounding of the result by other factors such as age, gender, or smoking. In the present study 12 female patients with osteoporotic fractures (Group O) and 14 normal women (Group N) were examined clinically for plaque (VPI), gingival bleeding (GBI), and loss of attachment on the 6 Ramfjord index teeth. Bone mineral content (BMC) of the mandible and forearm was determined by dual photon scanning. Results were presented as arithmetic means +/- standard error, and differences between groups were tested by 2-sample t-test. The two groups were comparable with respect to age (O: 68.3 +/- 1.8 years, N: 68.1 +/- 1.5 years), menopausal age (O: 47.5 +/- 1.8 years, N: 47.2 +/- 1.3 years), and smoking habits (O: 4 smokers, N: 3 smokers). The osteoporotic women had significantly lower BMC values than controls in the mandible (O: 0.63 +/- 0.04 in U/cm2; N: 0.78 +/- 0.02 in U/cm2, P < 0.01) and forearm (O: 1.05 +/- 0.05 in U/cm; N: 1.28 +/- 0.05 in U/cm, P < 0.01). No significant differences were found with respect to plaque (O: 46.67 +/- 10.00%, N: 36.67 +/- 6.67%) and gingival bleeding (O: 46.67 +/- 11.67%, N: 43.33 +/- 10.00%), whereas significantly greater loss of attachment was seen in osteoporotic women (O: 3.65 +/- 0.18 mm, N: 2.86 +/- 0.19 mm, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Osteoporosis: A Risk Factor in Periodontal Disease

The purpose of this study was to clarify if symptomatic osteoporosis is a risk factor for severe residual ridge reduction of the jaws. The analysis included 12 edentulous women with osteoporotic fractures, otherwise normal, and 16 normal edentulous women matched with respect to age, menopausal age, and period of edentulousness. The bone mineral content measured in vivo by dual-photon scanner was significantly lower in the mandible and the forearm bones (that is, in the skeleton) of the osteoporotic group than it was in the normal group. No significant difference between the two groups was demonstrated with respect to the size of the mandibular sagittal area, measured on identical lateral cephalograms, while the sagittal maxillary area was significantly smaller in the osteoporotic group. Symptomatic osteoporosis therefore seems to be a severe risk factor for smaller residual ridge reduction off the maxillae, while this does not seem to be the case in the mandible.

Symptomatic osteoporosis: a risk factor for residual ridge reduction of the jaws.

UNLABELLED The purpose of this study were to analyse 1) the changes in the bone mineral content (BMC) in mandibles with implant-supported overdentures when compared with the physiologic age-related mandibular BMC loss, 2) whether the BMC changes were different in groups without or with a bar connecting the implants and 3) whether the presence of mandibular osteoporosis affects the loss of bone height around the implants. The material consisted of 22 long-term edentulous healthy persons, 18 women and 4 men from 54 to 78 years of age with 1 Astra Tech Dental Implant in both canine regions, connected by a bar in half of the patients. BMC measurements were performed in vivo by dual-photon scanner at baseline, just after attachment insertion, at 2-year and 5-year visits. Mandibular osteoporosis was estimated by comparing baseline BMC values with normal mandibular BMC values for young adults of same gender. Loss of bone height around implants was measured on periodically identical intraoral radiographs. The fixed parts of the implant-system were stable during the trial in all patients. IN CONCLUSION 1) the increased function after this treatment seems to cause a load-related bone formation which minimizes the physiologic age-related mandibular BMC loss, 2) this effect seems to be independent of attachment system and 3) mandibular osteoporosis prior to implant treatment may be a risk factor for bone loss around implants. However, this treatment can be recommended also in osteoporotic persons.

Implant-supported overdentures, a prevention of bone loss in edentulous mandibles? A 5-year follow-up study.

The purpose of this study was 1) to reveal the short- and long-term precision of noninvasive in vivo measurements of bone mineral content (BMC) in larger and smaller parts of mandibles and in forearm bones by a new two-dimensional dual-photon attenuation system GT45; 2) to develop normal reference values and ranges for mandibular BMC in individuals between 20-40 yr of age without known systemic diseases and with normal oral state, (n = 56, F:M = 1:1), and 3) to relate mandibular BMC with forearm bone BMC, sex and age, by comparing BMC values of a well-defined normal old test group (n = 24, F:M = 1:1, 70-81 yr of age) with the normal reference values. The analyses indicated: 1) the in vivo short- and long-term precision of the methods is high. 2) BMC of mandibles and forearm bones is significantly related to sex and age (P less than 0.01, and in mandibles of young females/males: P = 0.02). 3) BMC in mandibles and forearm bones is significantly correlated in both age groups (P less than 0.01) with relatively weak coefficients of correlation. GT45 may be used to follow BMC changes in mandibles in groups or single individuals after surgical treatment and to evaluate sex and age dependent BMC changes in mandibles and forearm bones.

In vivo measurement of bone mineral content of mandibles by dual-photon absorptiometry.

Objective: To clarify the relationships between the varying clinical or radiographic features of cherubism. Study Design: Nonparametric statistics were used in a long-term follow-up of 18 patients through 2 generations from 6 Danish families. Results: The radiographic grade of cherubism was significantly related to sex, maximal buccal bone expansion, course of cherubism, and number of aplasia or ectopic impacted teeth, but it was not related to families. Normal dentition in nonaffected regions was present or was obtained in 14 of 14 patients (age, >14 years). Surgical treatment did not provoke growth of lesional tissue in 22 of 22 cases. Radiographically, the bone structure in the lesional areas was related to age in all grades of cherubism: new bone formation in radiolucent areas (age, >20 years), normal bone structure with multilocular sketches (age, 32 to 39 years), and completely normal bone structure (age, >41 years), also found in 7 of 7 carriers of cherubism (age, >32 years). Conclusions: This group analysis verifies the knowledge of cherubism previously based on cumulative reviews of findings in single-family and case reports. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;90:765-72)

Nina Von Wowern

Papers

Osteoporosis: A Risk Factor in Periodontal Disease

Symptomatic osteoporosis: a risk factor for residual ridge reduction of the jaws.

Implant-supported overdentures, a prevention of bone loss in edentulous mandibles? A 5-year follow-up study.

In vivo measurement of bone mineral content of mandibles by dual-photon absorptiometry.

Cherubism: a 36-year long-term follow-up of 2 generations in different families and review of the literature.