Oral submucous fibrosis: a report of two pediatric cases and a brief review

Oral submucous fibrosis is a chronic debilitating disorder which is usually seen in adults with areca nut chewing habit. A rapid upsurge in the popularity of commercial areca nut products, especially among the younger generation, is a cause of grave concern, as satisfactory management is still lacking. Hereby, two pediatric cases of oral submucous fibrosis are reported.     

Mandibular flexure and its significance on implant fixed prostheses: a review

Purpose: The aims of this review are to determine the effect of mandibular flexure on the “implant‐framework system,” and analyze the existing literature on the topic. Materials and Methods: A MEDLINE and PubMed search was conducted to identify any articles in English related to the topic published up to May 2010 using the search words “mandible,”“dental implants,”“dental impression technique,”“jaw movement,”“dental stress analysis,” and “mechanical stress.” Results: The search identified 40 and 36 articles from MEDLINE and PubMed, respectively. Twenty articles met the inclusion criteria. Conclusions: Mandibular flexure is a multifactorial phenomenon, and the effect of the implant‐framework system in this is unclear. Studies have focused mainly on the fully edentulous mandible. These have found that mandibular flexure should be taken into consideration when designing a prosthesis and have suggested that dividing the prosthesis at the symphysis region, or into multiple implant fixed dental prostheses, may minimize the effect of mandibular flexure on the implant prosthesis. At this time, no studies have investigated the effect of mandibular flexure on long‐span, unilateral, implant fixed prostheses. The clinical significance of mandibular flexure on the success of dental implant treatment is at this time unclear, and further research is needed.     

Does preoperative total parenteral nutrition in patients with ulcerative colitis produce better outcomes?

Purpose

Malnutrition is a frequent problem in patients with ulcerative colitis (UC) leading to increased postoperative complication rates. Preoperative total parenteral nutrition (TPN) has been shown to reduce complications in some subgroups of patients, but has not been studied in UC. We investigated the impact of preoperative TPN on postoperative complication rates in patients undergoing surgery for UC.

Methods

This paper is a review of 235 patients who underwent surgery for UC; 56 received preoperative TPN and 179 did not. Postoperative complication rates were compared.

Results

Both had similar rates of anastomotic leak (5.4 vs. 2.8?%, p?=?0.356), infection (12.5 vs. 20.1?%, p?=?0.199), ileus/bowel obstruction (21.4 vs. 15.6?%, p?=?0.315), cardiac complications (3.6 vs. 0?%, p?=?0.056), wound dehiscence (3.6 vs. 1.7?%, p?=?0.595), reoperation (10.7 vs. 3.9?%, p?=?0.086), and death (1.8 vs. 0?%, p?=?0.238). The TPN group was more malnourished (albumin 2.49 vs. 3.45, p?<?0.001), more often on steroids (83.9 vs. 57.5?%, p?<?0.001), had more emergent surgery (10.7 vs. 3.4?%, p?=?0.029), more severe colitis (89.3 vs. 65.9?%, p?=?0.001), and lower Surgical Apgar Score (6.15 vs. 6.57, p?=?0.033). After controlling for these with logistic regression, the TPN group still had higher complication rates (OR 2.32, p?=?0.04). When line infections were excluded, TPN did not significantly affect outcomes (OR 1.5, p?=?0.311)

Conclusion

There were no differences in postoperative complications when line infections were excluded. Our data does not support routine preoperative TPN in patients with UC. However, it may lead to equal surgical outcomes in the sickest and most malnourished patients at the cost of line-related morbidity.     

Structure–function relationship of working memory activity with hippocampal and prefrontal cortex volumes

A rapidly increasing number of studies are quantifying the system-level network architecture of the human brain based on structural-to-structural and functional-to-functional relationships. However, a largely unexplored area is the nature and existence of “cross-modal” structural–functional relationships, in which, for example, the volume (or other morphological property) of one brain region is related to the functional response to a given task either in that same brain region, or another brain region. The present study investigated whether the gray matter volume of a selected group of structures (superior, middle, and inferior frontal gyri, thalamus, and hippocampus) was correlated with the fMRI response to a working memory task, within a mask of regions previously identified as involved with working memory. The subjects included individuals with schizophrenia, their siblings, and healthy controls (n = 154 total). Using rigorous permutation testing to define the null distribution, we found that the volume of the superior and middle frontal gyri was correlated with working memory activity within clusters in the intraparietal sulcus (i.e., dorsal parietal cortex) and that the volume of the hippocampus was correlated with working memory activity within clusters in the dorsal anterior cingulate cortex and left inferior frontal gyrus. However, we did not find evidence that the identified structure–function relationships differed between subject groups. These results show that long-distance structural–functional relationships exist within the human brain. The study of such cross-modal relationships represents an additional approach for studying systems-level interregional brain networks.     

Composite polymerization stress as a function of specimen configuration assessed by crack analysis and finite element analysis

Objectives

To test the null hypothesis that polymerization-induced stress was not influenced by cavity dimensions and geometries.

Methods

Four experimental groups, with different C-factors and specimen volumes were defined using bottom-less glass disks (height: 1 or 2 mm) with a central hole 3 or 6 mm in diameter, and 3 mm wall thickness. Another four groups were created by bonding a glass plate to the bottom of the disks. Additionally, disks with 2-mm height, 3 mm in cavity diameter, and 4.5-mm thick walls were prepared. Vickers indents (9.8 N, 20 s) were made at the top surface at 600 μm from the cavity margin. The lengths of the indentation diagonal and the corner cracks parallel to the cavity margin were measured. Ten minutes after restoration (Majesty Esthetic, Kuraray), cracks were re-measured. Stresses at the indent site were calculated based on glass fracture toughness and increase in crack length. Data were subjected to ANOVA/Tukey or Kruskal–Wallis/Mann–Whitney tests (alpha: 5%, n = 8). Finite element analysis (FEA) was used to estimate stress at the interface and the effective structural rigidity of the substrate.

Results

Overall, for experimental and FEA results, cavities developed higher stress than bottom-less disks. Increasing wall thickness did not affect stress. When similar geometries and C-factors were compared, higher volumes developed higher stress and had greater incidence of margin cracking.

Clinical significance

C-factor is a suitable predictor for polymerization stress in low compliance environments, particularly due to its simplicity. However, the influence of cavity size cannot be disregarded especially for the development of marginal cracking. The interaction between size, geometry and stiffness is likely to become more complex according to the complexity of the cavity shape.