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

ObjectiveTo compare three mandibular trabeculation evaluation methods, clinical variables, and osteoporosis as fracture predictors in women.Study designOne 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.ResultsPrevious 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.ConclusionClinical and oral bone variables may identify individuals at greatest risk of fracture

Mandibular alveolar bone mass, structure and thickness in relation to skeletal bone density in dentate women

The aim of this series of studies was to investigate the relationship between skeletal bone mineral density (BMD) and mandibular alveolar bone mass (MABM), structure, and thickness, as well as to evaluate the possible effect of local functional factors on MABM and alveolar thickness. A further aim was to elucidate whether longitudinal changes in mandibular radiographic characteristics and the bucco-lingual dimension of the alveolar process were related to alterations of BMD. BMD was measured in 160 dentate women using dual X-ray absorptiometry of the forearm. On periapical radiographs MABM was estimated using densitometry and the grey-level value. The alveolar bone structure was evaluated with a visual index and by examining the bone texture on periapical radiographs. The thickness of the masseter was assessed with ultrasound imaging to estimate the masticatory functional factor, and the bucco-lingual alveolar thickness was measured on casts.MABM and alveolar structure were significantly correlated to BMD. The best correlation was found between BMD and trabecular pattern evaluated with the visual index (r=0.62, p<0.001). The alveolar thickness was correlated to BMD, and to masseter thickness. MABM was influenced of age, the alveolar thickness, the number of occluding teeth, and the masseter muscle thickness but these factors had no effect on the trabecular structure. After five years, all measurements except the ultrasound imaging of the masseter muscle were repeated in 136 women. The mean BMD, MABM, and alveolar thickness decreased significantly during this period, whereas no significant change was found in the bone structure. In posterior region, the alterations in alveolar bone thickness, radiographic grey-level value, and bone texture were significantly correlated to the changes in BMD. In the anterior region, the alterations in alveolar thickness were not correlated with the changes in BMD. Furthermore, no correlation was found between alterations in MABM, estimated by densitometry, and changes in BMD.In conclusion, a significant relationship exists between BMD and mandibular alveolar bone mass, structure, and thickness. The local functional factors mainly influence MABM and the alveolar thickness in the molar region, whereas BMD influences the trabecular structure. Dense trabeculation is a strong indicator of high BMD, whereas sparse trabeculation predicts low bone mass. In peri- and postmenopausal women the alveolar shape in the premolar region can be used to predict BMD level. In the lower premolar region, the longitudinal alterations in BMD are related to longitudinal changes in grey-level value, bone texture and alveolar thickness. The decrease in bucco-lingual alveolar thickness may be due to periosteal resorption related to skeletal bone loss

The relation between PhD students and their advisors: how to make it work and how to manage upcoming problems

Aims and rationale: The aim is to describe the experience of PhD supervision from the perspective of advisors and PhD students. PhD supervision is mostly done in a personal style that varies between advisors. For an outside observer it may seem that this works quite well. Can it be done better? The attrition rates and number of websites discussing how to survive your PhD suggests that there might be room for further improvement. Methods: Nine advisors from several university institutions in general practice in UK and Sweden and seven PhD students were interviewed. Principal findings: Three main themes were identified: 1) The good example: Eight house keeping rules were identified to facilitate a good relation between advisors and students. 2) Disagreements: Five areas for potential problems were identified and how these should be managed. 3) Potential consequences of a global trend in changing PhD programs from the former UK model (allowing more student initiative and "finding their way") to the US model (emphasizing low attrition rates and completion in time). Relevance to policy, research and/or practice needs: PhD students in general practice are often older than other PhD students and often do their PhD part time. They rarely fit into the standard PhD frame work made up by the University. This makes it important to clarify what can be done to facilitate research education in general practice

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

Background: PhD 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.\ud \ud Methods: Nine supervisors and seven PhD students from Sweden and England were interviewed using a video recorder. The recorded material was analysed using inductive content analysis.\ud \ud Results: Disagreements 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.\ud \ud Conclusions: There 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

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

Functional factors associated with continuous eruption of maxillary incisors in adulthood: a 10-year prospective cohort study

To investigate whether functional factors estimated by the masseter muscle thickness (MMT) and the maximum occlusal force (MOF), were associated with the amount of continuous eruption of maxillary incisors in adults