Inter-relationships between bone mineral content measures. Dual energy radiography (DER) and bitewing radiographs (BWX)

Soft tissue simulant materials in X-ray-based imaging in dentomaxillofacial radiology: a scoping review

INTRODUCTION

In in-vitro dental radiographic research, simulation of soft tissue is required to replicate the clinical condition as close as possible. This study aimed to find out which soft tissue simulation material have been studied to use in dentomaxillofacial radiology and showed similarity in radiodensity to the soft tissues of the maxillofacial region.

METHODS

In this scoping review, Web of Science, Embase, Scopus, Google scholar and PubMed databases were searched on April 9, 2023, considering the following PICOS: Population: soft tissue simulants, Intervention: X-ray-based imaging, Comparison: -, Outcome: properties of the soft tissue simulants, Study design: in-vitro studies. Screening, study selection, and data extraction were performed by two independent researchers. A third team member was consulted in the case of disagreement. Quality assessment of the included studies was made using Quality Assessment Tool For In-Vitro Studies (QUIN Tool).

RESULTS

Of the initial 1172 articles retrieved in the database search, 13 studies were included in the review. Seven studies had a low risk of bias. In 8 studies, computed tomography (CT) or cone beam computed tomography (CBCT), in 4 studies intraoral radiography, and in 2 studies panoramic radiography was used (one study has used CT/CBCT and panoramic radiography). The studies varied in the radiographic modality, acquisition parameters, selected outcomes, and gold standard. In the majority of the studies (n = 10, 77%), acrylic resin derivatives were used in the soft tissue simulant formula alone or as a major component. Wax was used in the simulant material in 8 studies (62%). In addition, in 3 studies (23%) ice/water was used as the main simulant.

CONCLUSION

Ballistic gelatin, expanded 2-cm thick polystyrene with or without 1-cm utility wax, and 0.5 cm of acrylic resin were shown to have a radiographic density similar to soft tissue in standardized studies employing CBCT scanning. For intraoral radiographs, using self-polymerizing acrylic resin, utility wax, and wood, as well as a polymethylmethacrylate box filled with water in thicknesses ranging from 4 to 45 mm, provides suitable radiographic contrast. However, for 4 and 8 mm of wax and 4 mm of water, the radiographic contrast is not appropriate. In addition, 13-17 mm wax and 14.5 mm acrylic resin showed acceptable soft tissue densities in intraoral radiography. Further studies using different imaging modalities with standardized conditions and objective metrics are required to confirm the most appropriate soft tissue simulant material for in-vitro dental radiographic research.

DIMITRA paediatric skull phantoms: development of age-specific paediatric models for dentomaxillofacial radiology research

OBJECTIVES

This report aims to describe the development of age-specific phantoms for use in paediatric dentomaxillofacial radiology research. These phantoms are denoted DIMITRA paediatric skull phantoms as these have been primarily developed and validated for the DIMITRA European research project (Dentomaxillofacial paediatric imaging: an investigation towards low-dose radiation induced risks).

METHODS

To create the DIMITRA paediatric phantoms, six human paediatric skulls with estimated ages ranging between 4 and 10 years- old were selected, protected with non-radiopaque tape and immersed in melted Mix-D soft tissue equivalent material, by means of a careful procedure (layer-by-layer). Mandibles were immersed separately and a Mix-D tongue model was also created. For validation purposes, the resulting paediatric phantoms were scanned using a cone-beam CT unit with different exposure parameter settings.

RESULTS

Preliminary images deriving from all scans were evaluated by two dentomaxillofacial radiologists, to check for air bubbles, artefacts and inhomogeneities of the Mix-D and a potential effect on the visualization of the jaw bone. Only skulls presenting perfect alignment of Mix-D surrounding the bone surfaces with adequate and realistic soft tissue thickness density were accepted.

CONCLUSIONS

The DIMITRA anthropomorphic phantoms can yield clinically equivalent images for optimization studies in dentomaxillofacial research. In addition, the layer-by-layer technique proved to be practical and reproducible, as long as recommendations are carefully followed.

Diagnostic accuracy of phosphor plate systems and conventional radiography in the detection of simulated internal root resorption

OBJECTIVE

To evaluate the performance of conventional radiography and photostimulable phosphor (PSP) plate in the detection of simulated internal root resorption (IRR) lesions in early stages.

MATERIALS AND METHODS

Twenty single-rooted teeth were X-rayed before and after having a simulated IRR early lesion. Three imaging systems were used: Kodak InSight dental film and two PSPs digital systems, Digora Optime and VistaScan. The digital images were displayed on a 20.1″ LCD monitor using the native software of each system, and the conventional radiographs were evaluated on a masked light box. Two radiologists were asked to indicate the presence or absence of IRR and, after two weeks, all images were re-evaluated. Cohen's kappa coefficient was calculated to assess intra- and interobserver agreement. The three imaging systems were compared using the Kruskal-Wallis test.

RESULTS

For interexaminer agreement, overall kappa values were 0.70, 0.65 and 0.70 for conventional film, Digora Optima and VistaScan, respectively. Both the conventional and digital radiography presented low sensitivity, specificity, accuracy, positive and negative predictive values with no significant difference between imaging systems (p = .0725).

CONCLUSIONS

The performance of conventional and PSP was similar in the detection of simulated IRR lesions in early stages with low accuracy.

Validity of wax and acrylic as soft-tissue simulation materials used in in vitro radiographic studies

OBJECTIVE

To determine the thickness of wax and acrylic that provides a radiographic density similar to that of the human cheek.

METHODS

An intraoral film radiograph of the human cheek including a 40×30×3 mm reference aluminium block was recorded under standardized conditions in 61 subjects. Radiographic density was measured by a densitometer in ten randomly selected sites of the film to serve as the gold standard for density values of the cheek soft tissues. Thereafter, the density of series of radiographs of two tissue-simulating materials-wax and acrylic-in systematically increasing thicknesses (wax, 1.5-30 mm; acrylic, 2-40 mm) plus the reference block were measured and compared with the gold-standard values.

RESULTS

The radiographic density of wax with a thickness of 13-17 mm or acrylic with a thickness of 14.5 mm corresponded to the average density of the human cheek.

CONCLUSION

The soft tissues of the average human cheek can be simulated with 13-17 mm wax or 14.5 mm acrylic in in vitro radiographic studies.

Comparative evaluation among different materials to replace soft tissue in oral radiology studies

Objective

The aim of this study was to establish which materials afford better simulation of soft tissues in Oral Radiology studies.

Material and Methods

The sample was composed of four materials in eleven different thicknesses to simulate the soft tissues of the face. The mean values of the relative amounts of radiographic contrast of the materials were determined and compared to a gold standard value, which was obtained from 20 patients who were referred to have periapical radiographs taken of the left mandibular molars. Data were subjected to statistical analysis with Dunnett's test (p<0.05).

Results

The mean value of the relative amounts of contrast encountered in the patients was 0.47, with a range between 0.36 and 0.64 for all 44 material/thickness combinations. The majority of the tested materials showed values close to those of the patients’ tissues, without statistically significant differences among them. The values of only three materials/ thickness combinations differed statistically from those of the patients’ tissues.

Conclusions

Based on the results of the present study, it may be concluded that except for utility wax (4 mm and 8 mm) and water (4 mm), all materials tested at different thickness could be used as soft tissue substitute materials in Oral Radiology studies.

Periodontitis and bone mineral density among pre and post menopausal women: A comparative study

AIM

The aim of the study was to assess the relationship between bone mineral density and periodontitis in premenopausal and postmenopausal women.

MATERIALS AND METHODS

Twenty women between the age group of 45-55 years were selected for this study. Ten premenopausal women with healthy periodontium constituted the control group and 10 postmenopausal women with ≥2mm of clinical attachment loss in >30% of sites constituted the study group. All patients were assessed for plaque index, probing depth and clinical attachment loss. Radiographs (six IOPA and two posterior bitewing) were taken and assessed for interproximal alveolar bone loss. The patients were scanned to assess the bone mineral density of lumbar spine (L2) and femur using dual energy X-ray absorptiometry (DEXA).

RESULTS

The bone mineral densities of lumbar spine (L2) and femur were significantly lower in the study group than the control group. Osteopenia of the lumbar spine and femur was observed in 60% whereas osteoporosis of lumbar spine was observed in 30% of cases in study group.

CONCLUSION

Increased proportion of osteopenia and osteoporosis cases of lumbar spine and femur in postmenopausal women with periodontitis suggests that there is association between bone mineral density and periodontitis.

Reliability of mandibular cortical index and mandibular bone mineral density in the detection of osteoporotic women

OBJECTIVES

Measuring the bone mineral density (BMD) of the femur and lumbar vertebrae has been the traditional method for determining osteoporosis in women. In this study, we tried to determine the relationships between mandibular dual-energy X-ray absorptiometry (m-DXA) values obtained with a new methodology, mandibular cortical index (MCI), total BMD values of the femur and lumbar vertebrae in 80 women with osteoporosis determined by DXA in conformity with T-score thresholds, as defined by the World Health Organization (WHO).

METHODS

m-DXA and panoramic radiography were performed on 80 women with osteoporosis. m-DXA was calculated by manual analysis of DXA scans. MCI was determined by the appearance of the mandibles on panoramic radiographs. DXA measurements of the skeletal BMD (femur and lumbar vertebras) and MCI values were also calculated. Correlations between these variables were assessed.

RESULTS

Although there were no correlations between skeletal BMD (total BMD values of the femur and lumbar vertebras) and mandibular measurements (mDXA and MCI), we found that there was a significant correlation between the skeletal BMDs (r = 0.355, P = 0.001).

CONCLUSIONS

It is concluded that no significant correlations were found between the mandibular and non-mandibular measures in women with osteoporosis.

Assessment of bone density differences between conventional and bone-condensing techniques using dual energy x-ray absorptiometry and radiography

OBJECTIVES

We used dual energy x-ray absorptiometry (DEXA) and periapical radiography to assess bone density differences after conventional and bone-condensing dental implant techniques.

STUDY DESIGN

Single-tooth dental implants were placed by both conventional and bone-condensing techniques in 14 patients with bilateral missing teeth. Dual energy x-ray absorptiometry was used to calculate bone mineral density (BMD) and bone mineral content (BMC) before and 6 and 12 months after implant placement. Furthermore, photodensitometry of periapical radiographs was also assessed.

RESULTS

The success rate was 92.9% for the conventional technique and 71.5% for the bone-condensing technique. The BMD was observed to be significantly higher 6 and 12 months after implant placement. The BMC and photodensitometry were significantly increased 6 months after implant placement but showed no further after 12 months.

CONCLUSIONS

There were no significant differences in BMD, BMC, and photodensitometry between the two implant placement techniques. However, success rate of the conventional technique was greater than the bone-condensing technique, which may be the result of trabecular fracture associated with the bone-condensing.

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.

Trabecular alveolar bone in the human mandible: a dual-energy x-ray absorptiometry study

OBJECTIVE

The purpose of this study was to evaluate the potential use of dual energy x-ray absorptiometry for the assessment of bone mineral content and bone mineral density before implant placement.

MATERIALS AND METHODS

The material examined consisted of 63 mandibular bone specimens cut from 21 fresh cadavers (11 men; 10 women). Three specimens were cut per cadaver in the incisal, premolar, and molar regions. Three regions of interest (G, R1, and R2) were delineated. The global bone specimen (G) consisted of the whole specimen (ie, both cortical and trabecular bone). R1 and R2 were delineated in the trabecular bone of the alveolar process.

RESULTS

In all subjects, the combined bone mineral content of the whole mandible specimens (global bone mineral content) was significantly correlated with age. The difference between the mean bone mineral densities of the male and female mandibles was found to be significant for G (P = .009). The mean bone mineral densities of dentate and edentulous specimens were also found to be significantly different for G and R1, respectively (P = .001 and P = .02), but not for R2. A positive correlation could be detected among the mean bone mineral density of G and R1, G and R2, and R1 and R2 of (1) male and female specimens, (2) dentate and edentulous specimens, and (3) incisal, premolar, and molar specimens.

CONCLUSIONS

The intra-alveolar trabecular bone of these 21 mandibles is affected by the same local and systemic influences as cortical bone, whereas the infra-alveolar trabecular bone is mostly sensitive to dental status. The cortical and trabecular bone of the 10 mandibles from women is more sensitive to systemic influences, whereas that from men is more sensitive to local influences. This is somewhat in agreement with some studies that found an association between osteoporosis and oral bone loss, which is a metric measure.

Estimation of skeletal bone mineral density by means of the trabecular pattern of the alveolar bone, its interdental thickness, and the bone mass of the mandible

OBJECTIVE

We sought to evaluate the use of the alveolar trabecular pattern, the mandibular alveolar bone mass (MABM) measured by photodensitometry, and the interdental alveolar thickness for prediction of the skeletal bone mineral density (BMD).

STUDY DESIGN

MABM and the coarseness of trabeculation were assessed by using periapical radiographs in 80 dentate women. The interdental alveolar thickness was measured on casts, and BMD of the forearm with dual X-ray absorptiometry.

RESULTS

Significant correlations were found between skeletal BMD and MABM (r = 0.46, P <.001) as well as the coarseness of the trabeculation (r = 0.62, P <.001). The interdental alveolar thickness improved the correlation between skeletal BMD and MABM (R2 = 0.44, P <.001). Age, but not interdental thickness, improved the correlation between the coarseness of trabeculation and skeletal BMD (R2 = 0.52, P <.001).

CONCLUSION

Evaluation of the coarseness of trabeculation of the alveolar bone as seen on intraoral radiographs is a helpful clinical indicator of skeletal BMD and better than densitometric measurements of the alveolar bone. Dense trabeculation is a strong indicator of high BMD, whereas sparse trabeculation may be used to predict low BMD.

Comparison of 5 protocols based on their abilities to use data extracted from digitized clinical radiographs to discriminate between patients with gingivitis and periodontitis

BACKGROUND

This study was undertaken to compare 5 digital analytic protocols for their abilities to extract data from digital clinical radiographs and discriminate between patients with gingivitis and periodontitis.

METHODS

Five digital-image analysis protocols were compared for their abilities to discriminate between two groups of 24 patients each. One group was diagnosed with healthy gingiva (or gingivitis) and the second with periodontitis. These groups were previously evaluated in published studies that used fractal and morphologic analyses. Pre-existing clinical radiographs for each patient were digitized and regions of interest (ROIs) were placed on interdental bone in mandibular posterior quadrants. The 5 protocols used were: 1) MGB: a median filtration to remove high-frequency noise, a Gaussian filtration to remove low-frequency noise, binarization of the resulting image, and quantification of the black pixels; 2) MGBS: the same protocol as MGB except for a skeletonization of the binary image and a quantification of the skeleton's pixels; 3) GBS: Gaussian filtration, binarization (thresholding on the mean pixel value) of the resulting image, skeletonization, and quantification of the pixels of the skeleton; 4) NS: normalization, skeletonization, and quantification of the skeleton's pixels; and 5) S: a variation of NS, except normalization was not used. The resulting values for the 2 patient groups were compared with Mann-Whitney U tests and effect likelihood-ratio test.

RESULTS

For digitized radiographs, the mean gray-scale value (+/- standard deviation) for gingivitis patients was 183.22 +/- 18.53 and for periodontitis patients 181.26 +/- 17.20. Mann-Whitney U tests resulted in the following P values for these protocols: MGBS <0.01; S <0.01; GBS <0.01; NS <0.01; and MGB <0.83. Effect likelihood-ratio tests indicated that only MGBS and S significantly contributed to models containing the other factors.

CONCLUSIONS

Small variations to protocols affected the strength of the discrimination between the gingivitis and periodontitis groups. While there is potential for morphologic analysis to be used to discriminate between patients with gingivitis and periodontitis, a robust technique was not identified.

Post-extraction remodeling of the adult mandible

Following tooth loss, the mandible shows an extensive loss of bone in some individuals. This may pose a significant problem in the prosthodontic restoration of function and esthetics. The many factors which have been proposed as being responsible for the inter-individual variation in post-extraction remodeling mean that a perfunctory analysis of the literature, in which well-controlled, relevant studies are scarce, may not provide the whole story. This article reviews the local and systemic factors which may play a role in the post-extraction remodeling of the mandible. Since severe residual ridge resorption may occur even when the bone status in the rest of the skeleton is good and vice versa, it is concluded that local functional factors are of paramount significance. It is now essential to determine how they can be modified and applied to help maintain ridge height and quality in our aging, edentulous population.

Mandibular bone mineral density measured using dual-energy X-ray absorptiometry: relationship to hip bone mineral density and quantitative ultrasound at calcaneus and hand phalanges

The main aim of this cross-sectional study was the estimation of relationships between mandibular bone mineral density (m-BMD), hip bone mineral densities (BMDs) and quantitative ultrasound at calcaneus and hand phalanges. Correlations between m-BMD and age, years since menopause (YSM) and body size were also evaluated. 42 edentulous persons (36 females and 6 males aged 60.5 +/- 6.9 years) were evaluated. In the group studied no factors affecting bone metabolism (either medical conditions or medications) were noted. Bone status was assessed by dual-energy X-ray absorptiometry (mandible, hip--Lunar DPX-L), and quantitative ultrasound (calcaneus--Lunar Achilles which measures speed of sound (SOS, m s-1) and broadband ultrasound attenuation (BUA, dB MHz-1); and phalanges of the hand--DBM Sonic 1200 which measures amplitude-dependent speed of sound (AD-SOS, m s-1)). CV% for mandibular measurements was 2.06%. m-BMD correlated significantly with the following measurements: femoral neck r = 0.39, p < 0.01; Ward's r = 0.39, p < 0.01; calcaneal BUA r = 0.39, p < 0.01; and phalangeal AD-SOS r = 0.4, p < 0.01. Negative correlation consistent with a significant decrease with age was observed in m-BMD (r = -0.36, p < 0.05) and AD-SOS (r = -0.4, p < 0.01). BMD in the mandible also decreased with YSM (r = -0.47, p < 0.01). m-BMD was correlated with age, YSM, height and weight in stepwise, multiple, linear regression analysis. The following equation was obtained: m-BMD = -2.21 + 0.018 x height (cm) -0.02 x YSM (years) + 0.13 x age (years). It may be concluded that mandibular BMD may be an appropriate measurement site for the evaluation of skeletal status in osteoporosis.

Toward an understanding of implant occlusion and strain adaptive bone modeling and remodeling

STATEMENT OF PROBLEM

Dental implant failure rates for osseointegration are greater in the highly atro-phic maxilla. Presuming higher failure rates relate to strain-driven adaptation, an enhanced understanding of formative bone response to loading (modeling) and maintenance of an integrated state (remodeling) should improve treatment.

PURPOSE

To understand the role of occlusal loading on long-term osseointegration in areas of compromised cancellous bone, a review of the salient features of adaptive bone modeling and remodeling is presented with an emphasis on cancellous bone responses.

CONCLUSIONS

The ability for dental implants to maintain a long-term stable interface in the maxilla lies in the ability of trabecular bone to maintain adequate local material (strength) and architectural (connectivity) properties. In this discussion, an emphasis has been placed on understanding how trabecular bone can respond to the mastication-induced loading environment on an implant.

The relationship between mandibular bone mineral density and panoramic radiographic measurements

OBJECTIVES

To compare densitometric and linear measurements (mandibular cortical thickness, MCT; panoramic mandibular index, PMI) made from dental panoramic tomograms (DPTs) with bone mineral density (BMD) values obtained using dual energy X-ray absorptiometry (DXA) of the mandible and to determine whether measurements from DPTs have validity in predicting BMD.

METHODS

Forty edentulous female patients were examined by a DPT incorporating a nickel step wedge and by DXA of the mandible. In each case the equivalent nickel thickness of sites in the mandibular body, MCT and PMI values were calculated and their relationship with DXA measurements assessed.

RESULTS

Densitometric measurements of DPTs did not correlate with mandibular BMD. MCT significantly correlated with mandibular BMD (r = 0.50, P = 0.001 and r = 0.36, P = 0.021 for repeated measurements) as did PMI (r = 0.37, P = 0.019 and r = 0.38, P = 0.016 for repeated measurements). All three measurements from DPTs had limited repeatability. MCT and PMI had moderate sensitivity and specificity for diagnosis of low mandibular BMD. Using ROC analysis, MCT and PMI measurements of one observer were significantly more valid than densitometry for diagnosis of low mandibular BMD.

CONCLUSIONS

It may be feasible to use MCT and PMI as diagnostic indicators of mandibular BMD, but further work is required to overcome problems with repeatability and to provide a larger patient sample.

Periodontitis detection efficacy of film and digital images

OBJECTIVE

The objective of this study was to evaluate the accuracy of alveolar crestal bone detection in a comparison of unenhanced and enhanced Sidexis (Siemens Medical Systems, Inc., Bensheim, Germany) digital images with Ektaspeed Plus (Eastman Kodak, Rochester, N.Y.) films by means of receiver operating characteristic analysis.

STUDY DESIGN

More than 100 proximal and furcal areas in the anterior and posterior areas of the mandible and maxilla of each of three tissue-equivalent human skull phantoms were imaged with film, direct digital images, and contrast- and brightness-enhanced digital images. Alveolar crest status was assessed by a consensus panel of three experts who used the Delphi method and evaluated information from all of the imaging modalities concurrently. Five observers assessed all images for the presence or absence of crestal bone loss using a five-point confidence scale. Receiver operating characteristic curves were generated, and calculated areas (Az) were analyzed by means of analysis of variance.

RESULTS

The expert panel determined that of 106 crestal areas, 48 were disease free and 58 exhibited bone loss greater than 2 mm apical to the cemento-enamel junction. Analysis of variance of observer Az scores showed significant differences among readers (p < 0.001) and among readings (p = 0.027), but not among modalities (p = 0.435). Mean Az values for the different modalities were as follows: Sidexis, 0.70; enhanced Sidexis, 0.71; Ektaspeed Plus films, 0.735.

CONCLUSION

The Sidexis digital imaging system was not significantly different from Ektaspeed Plus film for crestal bone evaluation in this in vitro study.

The relationships between two indices of mandibular bone quality and bone mineral density measured by dual energy X-ray absorptiometry

OBJECTIVES

To establish whether a relationship exists between the bone quality index (BQI), the mandibular cortical index (MCI) and bone mineral density (BMD) of the body of the mandible as measured by dual energy X-ray absorptiometry (DXA).

METHODS

Mandibular DXA and panoramic radiography were performed on 40 edentulous female patients. Mandibular body BMD was calculated by manual analysis of DXA scans. Panoramic radiographic appearances of the mandibles were assessed according to the BQI and MCI. All assessments were performed by two observers.

RESULTS

There were significant correlations between BQI and BMD (P < 0.01 for both observers) and between MCI and BMD (P < 0.005), but MCI was the more dominant of the two variables. Inter-observer agreement between BQI assessments was superior to that between MCI assessments. There were marked differences between intra-observer agreement for the two observers for both indices.

CONCLUSIONS

Both BQI and MCI are significantly related to BMD. However, particularly in the case of MCI, there were problems in repeatability of assessments which might limit their use in clinical practice.

Osteoporosis and oral bone loss

This paper is a review of the literature on the possible association between osteoporosis and oral bone loss, with an emphasis on radiological studies. Such an association was first suggested in 1960. Subsequent histomorphometric and microradiographic studies showed that after the age of 50 there was a marked increase in the cortical porosity of the mandible, with this increase being greater in the alveolar bone than the mandibular body; and that with this increase in porosity, there was a concomitant decrease in bone mass, which appeared to be more pronounced in females than in males, with the loss in bone mineral content estimated to be 1.5% per year in females and 0.9% in males. These studies also demonstrated a considerable amount of variation in the amounts of cortical and trabecular bone within and among individuals. Subsequent clinical studies reported associations between the bone densities of jaws and (1) metacarpals, (2) forearm bones, (3) vertebrae and (4) femurs. These studies indicated that women had lower mandibular bone mineral content (BMC) than men and that age-related loss of bone was more pronounced in women after the age of 50 years than in men of the same age, as was the case for the rest of the body. It was suggested that systemic factors responsible for osteoporotic bone loss may combine with local factors (periodontal diseases) to increase rates of periodontal alveolar bone loss. Although not all studies found associations between osteoporosis and oral bone loss, the conclusion of this review is that such an association exists; yet additional longitudinal investigations are needed to confirm this, and before the implications of this association could be fully utilized in clinical dentistry, inexpensive methods must be developed for sensitive and specific measures of oral bone loss.

Increased risk of tooth loss is related to bone loss at the whole body, hip, and spine

Increased systemic bone loss may be a risk factor for tooth loss by contributing to the resorption of tooth-supporting alveolar bone. Concurrent longitudinal associations between tooth loss and bone loss at the whole body, femoral neck, and spine were examined in 189 healthy, white, dentate, postmenopausal women who participated in three intervention trials conducted within a 7-year period. None of the subjects was taking estrogen. Bone mineral density (BMD) was measured by dual photon or dual energy X-ray absorptiometry. Teeth were counted at baseline; number and timing of teeth lost over the observation period were assessed by questionnaire. All analyses were controlled for years since menopause, body mass index, number of teeth at baseline, smoking status, and the assigned treatment during each study. These interventions were calcium (Ca) or placebo (P) in Study I, vitamin D+Ca or P+Ca in Study II, and 1 of 2 doses of vitamin D+Ca in Study III. Age at baseline (mean +/- SD) was 59 +/- 6 years and the number of teeth remaining was 23 +/- 7. Women who lost teeth during the 7-year follow-up (n = 45) experienced less favorable changes in BMD at all sites compared with 144 women who lost no teeth (whole body mean +/- SE, -0.35 +/- 0.08%/year versus -0.11 +/- 0.05, P < 0.01; femoral neck -0.48 +/- 0.38%/year versus -0.14 +/- 0.35, P < 0.05; and spine, +0.05 +/- 0.21%/year versus +0. 45 +/- 0.16, P < 0.05). For each 1%/year decrement in BMD, relative risks (and 95% CI) of losing a tooth were significantly elevated at the whole body (RR = relative risks, CI = confidence interval) (RR = 4.83, CI = 1.72-13.52, n = 180), femoral neck (1.50, 1.02 to 2.22, n = 189), and spine (1.45, 1.00 to 2.11, n = 167). These results provide support for a role of systemic bone loss in the development of tooth loss among postmenopausal women.

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.

Dual X-ray absorptiometry for alveolar bone: precision of peri-implant mineral measurements ex vivo

The precision of measurements of minor mineral changes in alveolar bone mineral content (ABMC) and alveolar bone mineral density (ABMD) on implant surfaces was determined in small regions (0.03 +/- 0.005 cm2) using dual X-ray absorptiometry (DXA). Dog hemimandibles with alveolar processes containing 17 implants were studied ex vivo. The precision was expressed as the coefficient of variation in percent (c.v. %). The ultra-high resolution protocol was applied to the mesial, distal and apical subregions of each implant. The line spacing was 0.0254 cm and the point resolution was 0.0127 cm. The mean c.v. (%) +/- s.d. for the ABMC in the mesial, distal and apical regions were 0.42 +/- 17, 0.47 +/- 0.21 and 0.48 +/- 0.18, respectively. For the ABMD these values were 0.42 +/- 0.16, 0.47 +/- 0.19 and 0.48 +/- 0.16. For each region approximately 68% of the 17 c.v. values were distributed within 1 s.d. from the mean c.v. These results indicate that measurements are highly reproducible (better than 0.48%) and that there are no differences in precision between several peri-implant regions. Changes as small as 0.85% in ABMC and ABMD in small areas adjacent to implant surfaces are measurable with a confidence level of 95%. Therefore the DXA technique will be expedient for our research evaluating the efficacy of the ceramic hydroxyapatite implant releasing agents affecting or inducing alveolar bone- and root cementum-like materials on its surface.

Spatial resolution in radiometric analysis of enamel loss. A pilot study

This pilot study was undertaken to determine whether spatial resolution affects radiometric analyses aimed at detecting progressive enamel loss. Four teeth were weighed, attached to a positioning device, and evaluated with radiography. A 1 mm strip of enamel was removed from each tooth, and the teeth were weighted again and reexamined by radiography. This process was repeated five times until 1/2 mm of dentin was removed. The radiographs were digitized twice with 59 and 200 microns pixels at 8 bits, providing two series of images with the optical densities converted into 256 gray levels. Each series of images was adjusted for contrast variation. Regions of interest were drawn on the crowns, and cumulative percent histograms (CPHs) were calculated. Within a series of CPHs enamel reduction resulted in shifts in the CPHs that were directly proportional to the amount of enamel removed. CPH shifts associated with the smaller 59 microns pixels accounted for 68% of the variation in weights caused by enamel reduction, whereas the shifts associated with the larger 200 microns pixels accounted for 50%. The results indicate that pixel size does affect radiometric determinations of enamel reduction.

Spatial resolution and angular alignment tolerance in radiometric analysis of alveolar bone change

This pilot study was undertaken to determine the effect of x-ray beam alignment and spatial resolution on quantification of alveolar bone using radiometric techniques. Six (6) dry mandibles were radiographed at 70 kVp, 10 mA, 0.6 seconds using D-speed film, with a bone chip (2.64, 4.10, or 6.07 mg) present or absent at 7 x-ray beam alignments (0 degree, 2 degrees horizontal, 2 degrees vertical, 4 degrees horizontal, 4 degrees vertical, 6 degrees horizontal, 6 degrees vertical). This resulted in 28 radiographs per mandible. Radiographs were digitized using 50- and 200-microns pixel spatial resolution. Image gray levels were standardized using a simple look-up table shift. Regions of interest (ROIs) were positioned on the alveolar bone where the bone chips had been placed. Cumulative percent histograms (CPH) were calculated for those ROIs. Regression analysis was used to evaluate the relationships between CPH changes and bone chip size as x-ray beam angulation and spatial resolution was varied. The resulting R2 values for angulation ranges of 0 degree to 1.4 degrees, 1.5 degrees, to 2.4 degrees, and 2.5 degrees to 5.5 degrees were: 0.983, 0.941, 0.891 for 50-microns pixel images and 0.869, 0.909, and 0.774 for 200-microns pixel images. We conclude that 50-microns pixel spatial resolution is apparently superior to 200-microns pixel images if radiometric data is to be evaluated. With 50-microns pixel spatial resolution, alignment variations up to 5 degrees may be acceptable in clinical studies, depending on the magnitude of bone change that is to be detected.

Digital radiographic images will benefit endodontic services

Future assurances for endodontic services and assessments of traumatized teeth will depend in part on significant improvements to the quality of dental radiographs. Whereas digital images offer many potential sensor, display and archival advantages over film-based radiographs, the marginal image improvements from intraoral sensors primarily benefit patient education. Precisely digitized conventional radiographs are more likely to yield quantum image resolution improvements, although neither dentists nor patients will benefit until cost-effective digitizing systems have been developed for the dental office.

When will excellent radiographic images be available to the general dental office?

Dental radiography is a highly regarded diagnostic practice. More than 25% of all radiographs are taken for dental purposes, so their improvement will benefit many patients. Although recent advances in materials and processing have contributed to incremental improvements in film-based diagnoses, computer-based enhancement of digitized conventional radiographic images is likely to yield more significant benefits. However, until cost-effective digitizing systems have been developed for the general dental office, the benefits derived from precise radiographic diagnoses and associated improvements in the standards of care will continue to elude both dentist and public.

Detection of simulated osteoporosis in human anterior maxillary alveolar bone with digital subtraction

The purpose of this in vitro study was to examine radiographic changes in human anterior maxillary alveolar bone during simulated osteoporosis (decalcification) and to determine the minimal amount of generalized decalcifications that can be detected under optimal radiographic conditions with the use of digital subtraction. Five samples of human anterior maxillary alveolus were progressively decalcified at timed intervals with 0.1 N hydrochloric acid solutions, and the percentage of calcium lost during each interval was quantified with calcium assays. Sets of four radiographs were exposed at 70 kVp initially and after each decalcification interval. The radiographs were digitized and digitally filtered, and bone profiles (scan lines) were generated between selected points on lead markers. To further reduce corrupting film-grain noise each set of four profiles were superimposed and averaged on a pixel-by-pixel basis. The averaged profile from each stage of decalcification was subtracted from the averaged initial profile on a pixel-by-pixel basis, and the mean profile intensity change for each decalcification stage calculated. Statistical analysis was performed with repeated measures analysis of variance. Results indicate that generalized decalcification less than or equal to 5.3% was detected in all samples of human anterior maxillae with the use of digital subtraction.