Evaluation of analgesic and anti-inflammatory effect of nanoparticles of magnesium oxide in mice with and without ketamine.

OBJECTIVES: According to importance and increasing application of nanoparticles and their toxicity, the identification effects of nanoparticles on physiological systems are essential. Some studies show magnesium has analgesic effect in some pain models but this evaluation was not carried on nano-magnesium oxide (MgO). Thus, present study was designed to evaluation effect of Mgo nanoparticles alone and in combination with ketamine on two pain and inflammation model in mice. MATERIALS AND METHODS: At this study, adult male mice was used which had 29±3 gram weight. Formalin and acetic acid tests were carried. Acetic acid (1%) was intraperitoneally injected 0.3ml and the abdominal writhing was counted from 10 to 30 minutes after it. Formalin (2.5%) was injected 0.04 ml/mouse subcutaneously in plantar site of mice.  The time of licking was cumulatively measured 0-5 (acute phase) and 15-25 (chronic phase) minutes later. Control (negative control), ketamine (0.1 mg/kg), MgO nanoparticles (5 and 10 mg/kg), conventional MgO (5 and 10 mg/kg) and ketamine with conventional and nanoparticles MgO groups were studied in both tests. RESULTS: Mean of writhing was significantly decreased by all drugs with comparison to control group (p = 0.0001). This decreasing was significant between conventional and nanoparticle MgO. The time of licking at both acute and chronic phases of formalin test was significantly decreased by all drugs with comparison to control group. However, this mean had significant difference with MgO nanoparticles. CONCLUSIONS: It seems that the nano-MgO induces analgesic and anti-inflammatory effects through central and peripheral mechanisms at experimental formalin and acetic acid testes and potentiates effect of ketamine.

Characteristics of effective clinical teachers identified by dental students: a qualitative study.

This qualitative research study identified criteria for clinical teacher quality preferences as perceived by dental students. Third and fourth year dental students at New York University College of Dentistry were given a two question, open-ended survey asking what qualities they liked most and least in a clinical teacher. Responses were collected until data saturation was achieved. A total of 157 respondents provided a total of 995 written comments. Descriptive words within the responses were coded and grouped into key words, according to similar relationships, and further refined into 17 defined categories. Three core themes, Character, Competence and Communication, emerged from these 17 categories, which were validated according to specific references found in the existing educational literature. 'Character' comprised nine of the 17 defined categories: (caring, motivation, empathy, patience, professionalism, available, fairness, happiness, patient-centred) and yielded 59.1% of total student responses; 'Competence' consisted of five categories: knowledgeable, expertise, efficient, skilful, effective (29.2%); and 'Communication' represented the remaining three categories: feedback, approachable and interpersonal communication (11.7%). Positive and negative responses related to the defined category of caring were cited by 59.2% of all students. Motivation was the next highest category, cited by 45.9% of students. Non-cognitive attributes, especially those in the Character theme, comprised the majority of student comments. Because students' perceptions are so critical to understanding clinical teaching effectiveness in dental education, these findings can be used to develop assessments to measure clinical teaching effectiveness, to create criteria for the hiring and promotion of clinical faculty and to plan faculty development programming.

Current perspectives in residual ridge remodeling and its clinical implications: a review.

PURPOSE: This article reviews the current understanding of the biology of tooth extraction wound healing and residual ridge remodeling. METHODS: The review of the biology of tooth extraction wound healing involves a discussion of the different cells populating the tooth extraction wound, the matrix formation, and the control of the repair process in the short-term. Defects in socket matrix formation or cellular activity will lead to stalled healing. The review of residual ridge remodeling describes the long-term result of tooth extraction and formation of residual ridges, in which the quantity of bone tissue continuously decreases. This may suggest that any potential regulatory factors of residual ridge resorption should have an adverse effect either on the increased catabolic activity by osteoclasts or on the decreased anabolic activity by osteoblasts. Both short-term tooth extraction healing and long-term residual ridge remodeling processes are interdependent. Furthermore, any potential genetic and environmental regulatory factors can affect the quality and quantity of bone by altering the gene expression events taking place in bone cells. RESULTS: The intent of this article was to review the current progresses of biologic research on residual ridge remodeling and to relate the changes at molecular, cellular, and tissue levels. The understanding of residual ridge remodeling may provide a sound scientific basis for improved restorative and therapeutic treatments of the edentulous population.

Effect of ovariectomy on the local residual ridge remodeling.

STATEMENT OF PROBLEM: Osteoporosis and edentulism are two disease processes that affect a large group of elderly people in the United States (24 and 25 million, respectively). These two diseases are independent of each other; however, they have several pathologic symptoms in common, such as reduction in bone mass. PURPOSE: The purpose of this study was to determine whether estrogen deficiency or its replacement therapy have any effect on the phenomenon of residual ridge remodeling. MATERIAL AND METHODS: Three animal groups were formed that consisted of six female Sprague-Dawley rats each. The two groups had ovariectomy and received either a vehicle solution or a daily dose (1.5 micrograms/day) of 17 beta-estradiol delivered through osmotic pumps. The control group underwent sham surgery and received a vehicle solution. Animals were pair fed throughout the experiment. Unilateral molar extraction was performed in the maxilla, which produced a suitable site for examination of histologic characteristics and molecular biologic analyses. At the 4-week postextraction period the bone remodeling activity was noted at the surface of the residual ridge in the control group. RESULTS: The ovariectomized group showed increased bone resorption activity, whereas the surface of the residual ridge alveolar bone of the ovariectomized and estrogen-treated group was covered by a layer of hyaline tissue. Poly(A)+ ribonucleic acid samples were isolated from the remodeling residual ridge tissues. Expression of alpha 2(I), alpha 1(II), alpha 1(IX), and alpha 2(X) collagens were examined by ribonucleic acid transfer dot blots. Compared with the control group, ovariectomized animals showed a reduction in bone formation with decreased expressions of type I and II collagens. In contrast, the estrogen-treatment group showed decreased formation of type I collagen with a much increased expression of type II collagen. Further examination of type II collagen formation on the ovariectomized and estrogen-treated group by means of in situ hybridization revealed the notable labeling by the type IIA collagen probe, which was associated with the surface tissue of the residual ridge alveolar bone. CONCLUSION: These findings suggest that estrogen deficiency and its replacement therapy seem to affect the activity of residual ridge bone remodeling at the molecular level.