Grethe Jonasson

Cervical thickness of the mandibular alveolar process and skeletal bone mineral density.

Much effort has been devoted to finding methods for detecting individuals with low bone mass and risk of osteoporotic fractures. The aim of the present study was to investigate whether there is a relationship between the thickness of the alveolar process and the bone mineral density (BMD) of the distal forearm. In 24 women (38-65 years), the BMD of the distal forearm, obtained by dual X-ray absorptiometry, was correlated to the difference between two measures of the thickness of the mandibular alveolar process in the region of the first premolar. A highly significant correlation (r = 0.95, P< 0.001) was found. The method was cross-validated by using the equation obtained from the linear regression analysis above to predict BMD in two other groups. In both groups, the correlation between the measured BMD of the forearm and the predicted BMD was highly significant (r = 0.91, P< 0.001). The interdental thickness between the canine and the second incisor was also correlated to BMD, but with lower predictive value (r = 0.67, P<0.001). Measurements of the mandibular alveolar process can be used as one of several parameters to predict skeletal bone density.

Mandibular bone changes in 24 years and skeletal fracture prediction

ObjectivesThe objectives of the investigation were to describe changes in mandibular bone structure with aging and to compare the usefulness of cortical and trabecular bone for fracture prediction.Materials and methodsFrom 1968 to 1993, 1,003 women were examined. With the help of panoramic radiographs, cortex thickness was measured and cortex was categorized as: normal, moderately, or severely eroded. The trabeculation was assessed as sparse, mixed, or dense.ResultsVisually, the mandibular compact and trabecular bone transformed gradually during the 24xa0years. The compact bone became more porous, the intertrabecular spaces increased, and the radiographic image of the trabeculae seemed less mineralized. Cortex thickness increased up to the age of 50 and decreased significantly thereafter. At all examinations, the sparse trabeculation group had more fractures (71–78xa0%) than the non-sparse group (27–31xa0%), whereas the severely eroded compact group showed more fractures than the less eroded groups only in 1992/1993, 24xa0years later. Sparse trabecular pattern was associated with future fractures both in perimenopausal and older women (relative risk (RR), 1.47–4.37) and cortical erosion in older women (RR, 1.35–1.55). RR for future fracture associated with a severely eroded cortex increased to 4.98 for cohort 1930 in 1992/1993. RR for future fracture associated with sparse trabeculation increased to 11.43 for cohort 1922 in 1992/1993.ConclusionDental radiographs contain enough information to identify women most at risk of future fracture.Clinical relevanceWhen observing sparse mandibular trabeculation, dentists can identify 40–69xa0% of women at risk for future fractures, depending on participant age at examination.

A prospective study of mandibular trabecular bone to predict fracture incidence in women: A low-cost screening tool in the dental clinic

Bone structure is the key to the understanding of fracture risk. The hypothesis tested in this prospective study is that dense mandibular trabeculation predicts low fracture risk, whereas sparse trabeculation is predictive of high fracture risk. Out of 731 women from the Prospective Population Study of Women in Gothenburg with dental examinations at baseline 1968, 222 had their first fracture in the follow-up period until 2006. Mandibular trabeculation was defined as dense, mixed dense plus sparse, and sparse based on panoramic radiographs from 1968 and/or 1980. Time to fracture was ascertained and used as the dependent variable in three Cox proportional hazards regression analyses. The first analysis covered 12 years of follow-up with self-reported endpoints; the second covered 26 years of follow-up with hospital verified endpoints; and the third combined the two follow-up periods, totaling 38 years. Mandibular trabeculation was the main independent variable predicting incident fractures, with age, physical activity, alcohol consumption and body mass index as covariates. The Kaplan-Meier curve indicated a graded association between trabecular density and fracture risk. During the whole period covered, the hazard ratio of future fracture for sparse trabeculation compared to mixed trabeculation was 2.9 (95% CI: 2.2-3.8, p<0.0001), and for dense versus mixed trabeculation was 0.21 (95% CI: 0.1-0.4, p<0.0001). The trabecular pattern was a highly significant predictor of future fracture risk. Our findings imply that dentists, using ordinary dental radiographs, can identify women at high risk for future fractures at 38-54 years of age, often long before the first fracture occurs.

The experience of disagreement between students and supervisors in PhD education: a qualitative study

BackgroundPhD supervision is mostly individual and disagreement between supervisors and PhD students is a seldom-discussed topic at universities. The present study aimed to describe the experience of disagreement between PhD students and supervisors.MethodsNine supervisors and seven PhD students from Sweden and England were interviewed using a video recorder. The recorded material was analysed using inductive content analysis.ResultsDisagreements in PhD education can be described with the overarching theme: the nature of the disagreements changes over time. Five categories emerged to describe the variations of the experiences: involvement in important decisions, supervisors not being up-to-date, dubious advice from supervisors, mediating between supervisors, and interpersonal relationships.ConclusionsThere is a gradual shift in competence where PhD students may excel supervisors in subject knowledge. Early disagreements may indicate immaturity of the student while disagreements later may indicate that the student is maturing making their own decisions. Consequently, disagreements may need to be addressed differently depending on when they occur. Addressing them inappropriately might slow the progressions and result in higher attrition rate among PhD students. The five categories may be elements in future PhD supervisor training programs and should be further evaluated for their importance and impact on PhD education.

Assessment of trabecular pattern on periapical and panoramic radiographs: A pilot study

Abstract Objective. This methodological study aimed to determine whether the mandibular trabecular bone assessment from panoramic radiographs, using a visual index, corresponds to the evaluation obtained from periapical radiographs. Material and methods. A panoramic radiograph and corresponding periapical radiographs of the region of the lower premolars and molars were collected from each of 32 patients (mean age 18.5 ± 5.5 years). Two calibrated observers assessed randomly the interdental sites between the first molar and second premolar and between the two premolars on all the radiographs using a visual index. Evaluations were repeated with an interval of 60 days. The results of the repeated evaluations were used to assess intra- and inter-observer agreements, employing Kappa statistics. Spearmans correlation was used to determine the association between assessments of panoramic and periapical radiographs. Results. In total, 79 interdental sites were evaluated on the panoramic and periapical radiographs. The visual analysis of periapical radiographs revealed intra-observer agreements of 0.88 for observer 1 and 0.93 for observer 2, and an inter-observer agreement of 0.82. The intra-observer agreement for panoramic radiographs was 0.79 and 0.83 for observers 1 and 2, respectively, and the inter-observer agreement was 0.79. A substantial correlation was found between periapical and panoramic radiographs (rho = 0.737, p = 0.001). Conclusions. Although panoramic radiographs are less reliable than periapical radiographs, they can be used for assessment of the trabecular bone pattern with the aid of a visual index. Training on the method is recommended to obtain results with a high reproducibility.

Trabecular pattern in the mandible as bone fracture predictor.

OBJECTIVEnThis investigation analyzed the use of mandibular sparse trabeculation as a fracture risk indicator.nnnSTUDY DESIGNnTrabeculation was classified as sparse, alternating dense and sparse, or dense using intraoral radiographs from 274 men and women (50-87 years old) including 56 with previous reported fractures. Mandibular bone texture was assessed on digitized radiographs.nnnRESULTSnForty-eight percent of subjects with sparse trabeculation reported fractures, compared with 19% with alternating sparse and dense trabeculation and 2% with dense trabeculation (Kruskal-Wallis test: P < .00001). Logistic regression analysis showed that sparse trabeculation (odds ratio [OR] = 5.9; 95% CI 3.0-11.1; P < .0001) and lowest bone texture classes (OR = 2.2; 95% CI 1.0-4.5; P = .04) were associated with an increased fracture risk, especially for subjects > or =75 years (OR = 7.1; 95% CI 2.5-20.0; P = .0002).nnnCONCLUSIONSnFracture risk was increased in subjects with sparse alveolar trabecular pattern. Dentists may be able to identify high-risk subjects before fracture.

Bone mass and trabecular pattern in the mandible as an indicator of skeletal osteopenia: a 10-year follow-up study

OBJECTIVESnThe aim of this investigation was to evaluate mandibular trabecular pattern as an indicator of osteopenia and bone mineral density (BMD) changes in relation to mandibular bone changes.nnnSTUDY DESIGNnForty females (49 to 80 years old) underwent intraoral radiography and BMD examinations 10 years apart. The trabecular pattern was assessed visually (Lindhs index), bone texture digitally, and bone mass by its grey-level values.nnnRESULTSnWith the exception of one subject, all individuals with sparse trabeculation were found to be osteopenic. All mandibular variables were tested for correlations with forearm and hip BMDs. They predicted forearm BMD, but adjusted for body mass index not hip BMD. Age, body mass index, and mandibular variables explained 29% to 64% of BMD variance. BMD changes correlated with body mass index change, bone texture change, and trabeculation change.nnnCONCLUSIONSnMandibular variables identify individuals with low BMD, but they are not discriminating enough for osteoporosis diagnostics. Mandibular bone changes correlated with forearm BMD changes.

Alveolar bone loss in osteoporosis: a loaded and cellular affair?

Maxillary and mandibular bone mirror skeletal bone conditions. Bone remodeling happens at endosteal surfaces where the osteoclasts and osteoblasts are situated. More surfaces means more cells and remodeling. The bone turnover rate in the mandibular alveolar process is probably the fastest in the body; thus, the first signs of osteoporosis may be revealed here. Hormones, osteoporosis, and aging influence the alveolar process and the skeletal bones similarly, but differences in loading between loaded, half-loaded, and unloaded bones are important to consider. Bone mass is redistributed from one location to another where strength is needed. A sparse trabeculation in the mandibular premolar region (large intertrabecular spaces and thin trabeculae) is a reliable sign of osteopenia and a high skeletal fracture risk. Having dense trabeculation (small intertrabecular spaces and well-mineralized trabeculae) is generally advantageous to the individual because of the low fracture risk, but may imply some problems for the clinician.

Mandibular trabecular bone as fracture indicator in 80‐year‐old men and women

The objective of the present study was to compare assessments of the mandibular bone as fracture risk indicators for 277 men and women. The mandibular trabecular bone was evaluated in periapical radiographs, using a visual index, as dense, mixed dense and sparse, or sparse. Bone texture was analysed using a computer-based method in which the number of transitions from trabeculae to intertrabecular spaces was calculated. The sum of the sizes and intensities of the spaces between the trabeculae was calculated using Jaw-X software. Women had a statistically significantly greater number of fractures and a higher frequency of sparse mandibular bone. The OR for having suffered a fracture with visually sparse trabecular bone was highest for the male group (OR = 5.55) and lowest for the female group (OR = 3.35). For bone texture as an indicator of previous fracture, the OR was significant for the female group (OR = 2.61) but not for the male group, whereas the Jaw-X calculations did not differentiate between fractured and non-fractured groups. In conclusion, all bone-quality assessments showed that women had a higher incidence of sparse trabecular bone than did men. Only the methods of visual assessment and trabecular texture were significantly correlated with previous bone fractures.

Mandibular bone structure, bone mineral density, and clinical variables as fracture predictors: a 15-year follow-up of female patients in a dental clinic.

OBJECTIVEnTo compare three mandibular trabeculation evaluation methods, clinical variables, and osteoporosis as fracture predictors in women.nnnSTUDY DESIGNnOne hundred and thirty-six female dental patients (35-94 years) answered a questionnaire in 1996 and 2011. Using intra-oral radiographs from 1996, five methods were compared as fracture predictors: (1) mandibular bone structure evaluated with a visual radiographic index, (2) bone texture, (3) size and number of intertrabecular spaces calculated with Jaw-X software, (4) fracture probability calculated with a fracture risk assessment tool (FRAX), and (5) osteoporosis diagnosis based on dual-energy-X-ray absorptiometry. Differences were assessed with the Mann-Whitney test and relative risk calculated.nnnRESULTSnPrevious fracture, gluco-corticoid medication, and bone texture were significant indicators of future and total (previous plus future) fracture. Osteoporosis diagnosis, sparse trabeculation, Jaw-X, and FRAX were significant predictors of total but not future fracture.nnnCONCLUSIONnClinical and oral bone variables may identify individuals at greatest risk of fracture.