A hands-on symmetry project is proposed
as an innovative way of
teaching point groups to undergraduate chemistry students. Traditionally,
courses teaching symmetry require students to identify the point group
of a given object. This project asks the reverse: students are instructed
to identify an object that matches each point group. Doing so requires
students to think about symmetry in their everyday environment and
aids in the development of a more intrinsic understanding of the assignment
of symmetry classifications.
Rehabilitation of oral function using dental implants is clinically effective and highly predictable. Both bone quantity and quality at the implant site affect the success of the procedure. However, the effect of bisphosphonate (BP) use on mandibular bone quality has not been well documented. The purpose of this retrospective cohort study was to evaluate the bone mineral density (BMD) and cortical thickness of the mandible, as well as the influence of BP use on early implant failure. Twenty-five female patients (≥60 years of age) were selected from among 93 candidates with partially edentulous posterior mandibles. Eleven patients had received BP therapy using alendronate (BP group), and 14 patients had received alternate therapy (non-BP group). Cortical and trabecular BMD was measured using quantitative computed tomography. Cortical thickness was measured using computed tomography. The BMDs and cortical thicknesses of the two groups were compared. The results were as follows: (1) Cortical BMD was significantly higher in the BP group, (2) trabecular BMD was not affected by BP use, and (3) Cortical thickness was affected by the duration of BP use. These results indicate that BP use affects the quality and quantity of the cortical bone in the partially edentulous posterior mandible of patients with osteoporosis, which should be considered prior to treatment with dental implants in patients taking BPs.
Background
In locations where the alveolar bone height is low, such as at the maxillary molars, implant placement can be difficult, or even impossible, without procedures aimed at generating new bone, such as sinus lifts. Various types of bone graft materials are used after a sinus lift. In our study, a three-dimensional image analysis using a volume analyzer was performed to measure and compare the volume of demineralized bovine bone mineral (Bio-Oss®) and carbonate apatite (Cytrans®) after a sinus lift, as well as the amount of bone graft material resorption. Patient data were collected from cone-beam computed tomography images taken before, immediately following, and 6 months after the sinus lift. Using these images, both the volume and amount of resorption of each bone graft material were measured using a three-dimensional image analysis system.
Results
The amount of bone resorption in the Bio-Oss®-treated group was 25.2%, whereas that of the Cytrans®-treated group was 14.2%. A significant difference was found between the two groups (P < 0.001).
Conclusions
Our findings indicate that the volume of bone resorption was smaller in the Cytrans®-treated group than in the Bio-Oss®-treated group, suggesting that Cytrans® is more promising for successful implant treatments requiring a sinus lift.
The proposed methodology to evaluate peri-implant mucosal thickness measured with a big variation from overall 3.6 mm with a big variation from 1.6 to 7.0 mm in healthy volunteers. And significant difference was found in the depth among the three regions and, statistically, dispersion of individual peri-implant mucosal thickness resulted in lack of consistency. Although dental implants have been well developed, predictable and prevailing prosthetics, onset of peri-implantitis might be inevitable in some cases. Therefore, establishment of a standardized dimensional diagnosis of peri-implant tissues followed by pathologic ascertainment could be taken into account for the prevention or curing of peri-implantitis.
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