Microhabitat use affects goby (Gobiidae) cue choice in spatial learning task.

This study investigated whether spatial learning ability and cue use of gobies (Gobiidae) from two contrasting habitats differed in a spatial task. Gobies were collected from the spatially complex rock pools and dynamic, homogenous sandy shores. Fishes were trained to locate a shelter under the simulated threat of predation and it was determined whether they used local or extra-maze (global) and geometric cues to do so. It was hypothesized that fishes from rock pools would outperform fishes from sandy shores in their ability to relocate shelter and the two groups would differ in their cue use. It was found that rock-pool species learnt the location of the correct shelter much faster, made fewer errors and used a combination of all available cues to locate the shelter, while sand species relied significantly more on extra-maze and geometric cues for orientation. The results reported here support the hypothesis that fishes living in complex habitats have enhanced capacity for spatial learning and are more likely to rely on local landmarks as directional cues than fishes living in mundane habitats where local cues such as visual landmarks are unreliable.

An in vitro evaluation of microleakage in class I preparations using 5th, 6th and 7th generation composite bonding agents.

The intent of this study was to evaluate microleakage of newer generations of dentinal bonding systems of Class I restorations filled with the same resin based composites. Eighty extracted human premolar and molar teeth were randomly assigned to four groups for bonding: the 5th generation bonding system (Optibond Solo), the 6th generation bonding system (Prompt-L-Pop) and the 7th generation bonding system (iBond), and a control group that was used with no dentinal bonding system. Cavities were prepared 3 mm in width, 2 mm in depth and 2 mm in length. Margins of the cavities were chamfered using a high-speed hand piece with water spray and a #1/2 round diamond bur. The cavities were restored with resin based composites after the application of the dentinal bonding systems according to the instructions of the manufacturer. Upon drying of the teeth, two coats of nail varnish were applied covering the surface of the tooth, excluding the tooth-restoration interface. Samples were thermocycled and immersed in methylene blue dye (0.05%). Each sample was sectioned with an Isomet and evaluated, for microleakage using light microscopy under a measuring microscope at 50x magnification Statitical significance was determined using the Chi-Square Test. Among the three dentinal adhesive systems used in this study the 5th generation outperformed both the 6th and 7th generation bonding systems.

Orthopedic approach in the treatment of a skeletal class II division 1 malocclusion with an anterior open bite.

The patient presented with a skeletal class II malocclusion characterized by an anterior open bite and maxillary midline deviation. This mixed dentition case was treated orthopedically with MRI appliance to rotate and impact the maxilla. A Bionator was used advance the mandible. The case was completed using Occlus-O-Guide. The result showed that the facial bones and teeth appear in the correct position.

Polyethylene ribbon fibers: a new alternative for restoring badly destroyed primary incisors.

Dentistry has advanced to the point where it is undesirable for children to be partially edentulous or to have unattractive anterior teeth. With the introduction of new materials and adhesive systems the use of polyethylene fibers as post and core offer a new reconstructive alternative for severely destroyed primary anterior teeth. These fibers offer root and coronal retention, stability and esthetics, and it is done chair side. The present study compared two different types of fibers and analyzed the fracture resistance between the two of them. Two groups were formed. Group I used non pre-impregnated resin fibers (glasSpan) and group II used pre-impregnated resin fibers (Splint-it). Both types of fibers have been used as post and core in the restoration of primary teeth and clinical studies have been published. Our results indicated that the mean fracture resistance for group I was 71.346 and for group II 97.952 (p = 0.004). During the observation of the fractured samples, adhesive failures were noted for group I at the junction between the fiber and its core to the interior wall of the root canal. In group II, the fibers were dislodged out of the canal and the core part of the canal remained intact. It can be concluded that pre-impregnated fibers offer a better fracture resistance when used as post in endodontically treated primary anterior teeth.

A newer approach in positioning teeth for dental prosthetics using lateral cephalometric, trans-cranial radiographs, and the Denar-Witzig articulator: a case of hypodontia in an adolescent patient.

Traditionally in full denture prosthetics, anterior teeth are set on the models, independent of the effects on the face. More enlightened dentists, will then adjust the wax-up for speech, and some effects on the lips. Consideration is infrequently given to restoring the face by repositioning the teeth and mandible. Rarely is thought given to the effects of occlusion on the posture of the body. This report uses several techniques to restore facial esthetics and body posture. The techniques used include a cephalometric radiograph, transcranial radiographs, an articulator that has an adjustable "TMJ" (Denar-Witzig), and Symmetrigraf Posture Chart. This clinical report describes a newer approach in the positioning of maxillary anterior teeth for a patient with hypodontia and nail dysplasia syndrome, and the overall effect of this approach on the face and posture of the patient. Conventionally the precise form of the maxillary wax rim is fabricated with considerable variation from technician to another, based on the technicians training. This variation is evident on the position of the labial aspect of the rim horizontally and vertically. The wax rim is then further adjusted chair side based on subjective evaluation of the face. The maxillary anterior teeth position is established without considering that the lip position is not yet accustomed to the wax rim.

Intraoral craniofacial manipulation by using MRI appliance.

This case illustrates the use of the Maxillary-Rotation-Impaction Appliance (MRI) to rotate and impact the maxilla. When this maneuver was completed the transverse expansion screw widened the maxillary arch. The case was completed using fixed orthodontic appliances. The result is that the facial bones appear in the correct position and the teeth are correctly positioned in the face with a class I occlusion.

Mandibular deviations in TMD and non-TMD groups related to eye dominance and head posture.

This study was designed to determine whether eye-dominance affects head posture (rotation) and in turn, whether head posture is associated with mandibular frenum midline deviation, in both TMJ and control subjects. Eye dominance was determined using three tests: Porta, Hole, Point tests. Natural head posture was evaluated using the Arthrodial protractor. Mandibular frenum deviation was recorded as left, right or no deviation. Fifty female subjects were included in the study, 25 TMJ patients attending the Gelb Craniomandibular Pain Center and 25 non-TMJ control subjects. The findings indicate that eye dominance and direction of head rotation are strongly associated in both TMJ and control subjects. Further, in TMJ subjects mandibular deviation occurred in greater frequency than in controls and tends to occur in the contra lateral direction of head rotation.

Attention-deficit/hyperactive disorder: making a case for multidisciplinary management.

Attention Deficit/Hyperactivity Disorder (AD/HD) is characterized by a cluster of age-inappropriate behavioral abnormalities comprising inattentivity, hyperactivity and impulsivity. The definition is controversial and without an accurate diagnosis. Therefore, it seems prudent that a multidisciplinary treatment protocol should begin with non-drug psychological and behavioral strategies plus nutritional intervention.

Sexual harassment during medical training: the perceptions of medical students at a university medical school in Australia.

CONTEXT: A survey of medical students' experiences of sexual harassment during medical training. OBJECTIVE: To assess the prevalence and nature of workplace sexual harassment as perceived by undergraduate medical students in order to address their learning needs concerning setting and maintaining sexual boundaries. DESIGN: A questionnaire involving both quantitative and qualitative descriptions. SETTING: A university medical school in Australia. PARTICIPANTS: The medical student population. MAIN OUTCOME MEASURES: Estimated prevalence of sexual harassment according to gender and year of training; frequency of sexual harassment reported by category of behaviour, year of training and gender; type of sexual harassment and alleged harasser reported by gender; frequency of sexual harassment reported by category of behaviour and alleged harasser. RESULTS: Female students encountered an unacceptable amount of sexual harassment in medical training from fellow students, patients, faculty and doctors they worked with, which was perceived as affecting learning opportunities. CONCLUSION: Genderized sexual harassment exists in medical training. While both male and female students report episodes perceived as sexual harassment a difference in interpretation results in greater vulnerability for female students. Medical educators need to address issues of gender, sexual harassment, and the setting and maintaining of sexual boundaries in order to avoid a hostile learning environment.

An in vitro study of microleakage of pit and fissure sealants in the presence of occlusal forces.

The purpose of this study was to evaluate the effect of load on microleakage of pit and fissure sealants. In the first phase of the study load of maximal force (F = 880 N) on central and peripheral enamel was applied. Three groups of ten specimens were tested for microleakage. Group A no application of load, Group B application of load on the central pit of the tooth, and Group application of load on the peripheral enamel 2.5 mm away from the margin of the tooth, at the level of dentinoenamel junction. The results of that study showed significant increase of microleakage on the peripheral sealed enamel, as well as enamel microcracks. So, in the phase II sixty wisdom teeth were sealed with Ultra seal XT plus and load of different magnitude was applied on the peripheral enamel. The specimens were thermocycled for 500 cycles at 5 degrees C and 55 degrees C with a dwell of 30 seconds at each temperature prior to load application. Six groups of ten specimens were tested for microleakage under load. The force was applied at the peripheral enamel, 2.5 mm away from the margin of the tooth, at the level of dentin-enamel junction in cross-section view. Group A: F = 0 N; Group B: F = 300 N; Group C: F = 400 N; Group D: F = 500 N; Group E: F = 600 N; Group F: F = 700 N. Microleakage was scored as distance of dye penetration with 0 = no microleakage and 3 = microleakage to underlying fissure. A linear regression statistics was used with R-squared of 0.31. The groups with load applied (B, C, D, E, F) showed statistically significant results (p < 0.05) compared with group A (F = 0 N). Both, the magnitude of the force and tooth morphology may influence the degree of microleakage observed after the placement of sealants.

Enameloplasty effects on microleakage of pit and fissure sealants under load: an in vitro study.

Enameloplasty has been implicated in the successful application of pit and fissure sealants. The present study aimed to evaluate the effect of enameloplasty technique on microleakage of sealants when occlusal force was applied on the teeth. The study also allowed a direct comparison of the effectiveness of enameloplasty, when two different burs were used. Six groups of ten human extracted wisdom teeth were tested. Group A: no load, conventional (no enameloplasty--control); Group B: no load, enameloplasty 1/2 round bur (Brasseler USA); Group C: no load, enameloplasty diamond fissure bur REF/UP 791 (Ultradent); Group D: load 500 N, conventional, Group E: load 500 N, 1/2 round bur; Group F: load 500 N, diamond fissure bur. Specimens were thermocycled for 500 cycles at 5 degrees C and 55 degrees C with a dwell time of 30 seconds after load application. Microleakage was scored as distance of dye penetration with 0 = no microleakage and 3 = microleakage to underling fissure. The Kruskal-Wallis One Way Anova and Mann-Whitney U test showed group D having the greatest degree of microleakage statistically significant (p < 0.05) comparing with other groups. Sealants prepared with the conventional technique (A, D) had statistically significant differences in microleakage with those prepared with enameloplasty (B, C, E, F) (p = 0.01). Enameloplasty in groups with no load (B, C) did reduce microleakage, but not significantly (p = 0.3). However, loaded teeth with enameloplasty appeared to perform superior, as compared to those without (p = 0.005). Regarding the effect of load, teeth without load (Groups A, B, C) were found to have significantly less microleakage than teeth where mechanical force had been applied (Groups D, E, F), (p = 0.01). Microleakage in Group A (conventional technique without load) was significantly less than microleakage in Group D (conventional technique with load), (p = 0.04). However, load did not seem to influence microleakage when enameloplasty had been performed. This finding was true for both round bur enameloplasty (p = 0.29), and fissure bur enameloplasty (p = 0.26). There was no statistically significant difference between Groups B, E (round bur) and C, F (fissure bur) (p > 0.05), or between Groups B and C (p > 0.05) and between Groups E and F (p > 0.05). The results of the study indicated that enameloplasty reduced microleakage of pit and fissure sealants, especially when load was applied to teeth, irrespective of what bur was used to enlarge the fissure, as there was no statistical significant differences between the round and fissured diamond burs. The application of occlusal force to the tooth produces significantly more microleakage, unless enameloplasty is performed.

Perspectives in posterior vertical dimension: three case reports.

Using a powerful three dimensional perspective, it is possible to control the vertical components of bite opening appliances, which can prove to be valuable in design and application of functional appliances. Several cases are presented to illustrate this orthopedic technique.

Newer Class I cavity preparation for permanent teeth using air abrasion and composite restoration.

This study attempts to determine a more effective cavity preparation design, material selection and preparation technique for reducing microleakage in posterior Class I esthetic restorations. An in vitro study using four different cavity designs, for Class I restorations on permanent molars, prepared with two different methods, and restored with three different restorative materials (hybrid composites) was done to evaluate marginal microleakage, and voids occurrence. Two hundred and forty extracted permanent molars were chosen and evaluated for caries, visually, with a dental explorer, and with caries detector dye. The teeth were then randomly divided in two groups (n = 120). In the first group, Class I cavity preparations were performed with air-abrasion. In the second group Class I cavity preparations were performed with #330 bur. The results revealed that cavity preparations prepared with air-abrasion with or without chamfer, and for cavity preparations done with a #330 bur with chamfer and restored with Tetric Flow, had zero microleakage. Cavity preparations done with air-abrasion, without chamfer, and for cavity preparations prepared with #330 bur with chamfer and restored with Tetric Ceram, had zero microleakage score. Cavity preparations done with air-abrasion with chamfer and restored with Herculite had one tooth out of twenty with microleakage, and for cavities without chamfer two teeth had microleakage. Cavity preparations prepared with a #330 bur, without chamfer, and restored with Herculite XRV had four teeth out of twenty with microleakage, and with a chamfer, two teeth had microleakage. These differences were not statistically significant. When comparing Tetric Flow versus Herculite XRV for void formation in cavity preparations prepared with Air-abrasion and a chamfer, Tetric Flow had significantly less voids, p < 0.001. When comparing Tetric Ceram versus Herculite XRV for cavity preparations prepared with Air-abrasion and a chamfer, Tetric Ceram had significantly less void formation, p < 0.01 > 0.001. When comparing Tetric Flow versus Herculite XRV for cavity preparations prepared with #330 bur and without a chamfer, Tetric Flow had significantly less void formation, p < 0.02 > 0.01. When comparing Tetric Flow versus Herculite XRV for cavity preparations prepared with #330 bur and a chamfer, Tetric Flow had significantly less void formation, p < 0.001 > 0.001. Caries detection results revealed that the caries detector dye method had significantly higher caries detection scores than explorer p < 001, and than visual inspection p < 0.001. Also inspection with explorer had significantly higher scores than visual inspection p < 0.001.

Combined effects of argon laser irradiation and fluoride treatments in prevention of caries-like lesion formation in enamel: an in vitro study.

The sample of this study consisted of 10 human permanent molars, which were sectioned into tooth quarters using slow speed diamond saw (Isomet), then a quarter from each tooth was assigned to one of four treatment groups: A) control (no treatment); B) argon laser only; C) argon laser plus neutral sodium fluoride for 4 minutes; D) argon laser with zinc fluoride for 4 minutes; each tooth quarter was coated with acid resistant varnish, leaving a window of 2 mm x 3 mm of sound enamel exposed. The results were that teeth treated with argon laser and then with zinc fluoride for four minutes have significantly reduced white spotting or etching. Zinc fluoride and argon laser combination are particularly effective in compensating for carbonate inclusion. It has a property of stabilizing hydroxyapetite crystal and restoring the structural defects of this crystal. Caries detection dye is a reliable diagnostic tool for white spot lesions. It reduces the false positive and false negative results by 60%, when compared with visual 16x magnification.

Correction of a Class III malocclusion with a four-way sagittal appliance: case report.

This case report demonstrates the treatment of a Class III malocclusion, in a twelve-year-old girl, using a unique combination of a removable functional appliance, the "four-way sagittal" appliance and fixed appliance therapy. Efficient and effective correction of malocclusion was attained, following use of the "four-way sagittal" appliance. This appliance was designed on the Denar Witzig articulator, a powerful instrument in providing the clinician with a three-dimensional perspective plus the ability of changing the location of the TMJ on the articulator. A significant increase in the maxillary length and maxillary width was achieved.

Women planning and experiencing pregnancy and childbirth: information needs and sources.

This paper reports the preliminary findings of a study of women planning a pregnancy and perinatal women with respect to their information needs and the sources of information they use. Fifty women, 7 planning a pregnancy, 30 pregnant and 13 postnatal, completed a questionnaire including questions about who they had approached for information about pregnancy issues, who had given them advice and why it was or was not useful, what they would currently like to know, and what they wished they had known during the previous three months. Results highlighted differences in the type of information provided by various sources: doctors and specialists were seen as primarily providing factual information; midwives also supplied information but more importantly gave reassurance and support; partners did not provide information but were valued for their support in a shared experience; and mothers and friends were primarily useful due to their own experiences. The findings also suggested the importance of information that is relevant to the women's current stage of pregnancy.

The importance of occlusal balance in the control of complete dentures.

OBJECTIVE: The importance of occlusal balance to the control of complete dentures during function was assessed. METHODS AND MATERIALS: The complete dentures of five patients who were having difficulty controlling their prostheses were accurately duplicated. The artificial teeth were replaced with occlusally balanced teeth. No other changes were made. Patients were asked to report their experiences with the new dentures after 1 week, 3 weeks, and 6 weeks. RESULTS: By the end of 6 weeks, improvement in denture stability and eating comfort were reported by all patients. CONCLUSION: Improvements occurred when the occlusion was balanced, despite existing jaw relationship errors, fitting inaccuracies, and peripheral extension errors.

Class III cavity preparation in primary anterior teeth: in vitro retention comparison of conventional and modified forms.

Management of mild to moderate caries in primary anterior teeth is still a problem. Presently, class III composite restorations in primary teeth have inadequate retention. The purpose of this in vitro study was to analyze the influence of the design of modified class III cavity preparation on the retention of the restoration when compared to that of the conventional class III preparation. Thirty extracted human primary maxillary central incisors were divided into two groups of 15 teeth each. In one group, the conventional (triangular) class III design was prepared. The second group, the modified class III design, was prepared by adding to the conventional form, 0.5 mm. labial reduction on the labial tooth surface. The dentinal bonding agent, Amalgambond, was applied to 30 teeth according to instructions of manufacturer. The composite resin, Herculite XRV, was inserted into each preparation. All samples were mounted in plastic molds and thermocycled. The samples were tested with Instron testing machine until restoration failure. Results showed that the mean failure load of modified class III restoration group (92.19 +/- 13.6 N) was significantly higher from that of conventional class III preparation group (45.61 +/- 9.8 N) as tested by Student's independent t-test (P < 0.001).

Chamfered margin effects on occlusal microleakage of primary molar Class I composite resin restorations in vitro.

Recent clinical studies have suggested that composite resin may be an effective restorative material for the restoration of Class I preparation in primary molars. The primary objective of this study was to assess the effects in vitro of a chamfered margin on occlusal microleakage of class I posterior composite resin restorations in primary molars. Two cavity preparations (conventional and modified) were compared by using forty extracted primary molars. The modified class I preparation as described in this study showed no occlusal microleakage and recommended to be further studied clinically. The difference between these two groups was analyzed by using the Fisher Exact Probability Test and was statistically significant.