Influence of impression material and time on the 3-dimensional accuracy of implant impressions.

OBJECTIVE: To investigate, in vitro, the effect of time on the 3-dimensional accuracy of open-tray implant impression copings made of polyvinyl siloxane and polyether impression materials. METHOD AND MATERIALS: Reference models with 4 internal connection implants were fabricated. Four sets of 71 direct impressions were made with square impression copings using an open-tray technique. One set of impressions was made with polyether material (material A) and each of 3 polyvinyl siloxane materials (materials B, C, and D). Three-dimensional changes in spatial orientation of the implant analogs were measured over 48 hours using an optical measurement device. Deviation values were summed over 4 points and averaged per impression. Global differences were tested with a nonparametric Kruskal-Wallis test followed by pairwise comparisons using the Mann-Whitney U test. RESULTS: The mean dimensional accuracy of implant impressions significantly differed over time (P < .001). Materials A and B were found to produce comparable results, For materials C and D there was a significant increase in deviations, with a maximum increase at 2 hours. Deviations for material C were comparable to materials A and B at 48 hours. Baseline values were not maintained by any material. CONCLUSIONS: Within the limits of this in vitro study, it can be concluded that time cannot be neglected as a factor affecting the accuracy of implant master casts.     

PBL core skills faculty development workshop 1: An experiential exercise with the PBL process

This report describes the first in a series of foundation-building faculty development workshops focused on the instructional methodology of problem-based learning (PBL). The PBL Process workshop reported here introduced the learning theory topics supporting PBL and utilized an extended roleplay method to provide participants with personal experience with the PBL learning cycle. Overall, participants were satisfied with the methods and content of the workshop. A majority of survey respondents indicated that simulating a complete iteration of the PBL process was an effective way to learn about PBL. Participants expressed relatively greater difficulty understanding and performing activities related to qualitative assessment of learning processes. The workshop was developed to align with adult learning principles, and continued refinement of the workshop has enhanced the learning theory components underpinning PBL as well as the experiential aspects. These dual goals have resulted in blending the existing experiential workshop with an online distance-learning component addressing the learning theory topics relevant to PBL pedagogy.     

Reconstruction of the temporal contour for traumatic tissue loss using a CAD/CAM-prefabricated titanium implant-case report

INTRODUCTION: A 16-year-old Arab boy had suffered from a severe head injury including an intracranial haematoma. Despite replantation of the bone flap later on, the cosmetic result was very unfavourable due to partial resorption of the reinserted bone and atrophy of the right temporalis muscle. AIM: For contour reconstruction of both soft and hard tissues the boy was transferred from Saudi Arabia. METHOD: A spiral CT was obtained and the contour was reconstructed using a new algorithm for surface generation. RESULT: The resulting titanium implant was inserted without complications or the need for revision. The cosmetic result was good and corresponded to the preoperative digital planning. CONCLUSION: Techniques of computer-assisted implant prefabrication and surgery may include special algorithms for considering soft tissues including contour deficits of the temporalis muscle.     

Glomus tumor of the index finger

A 41-year-old female patient presented with localized worsening subungual pain of her right index finger. Subsequent diagnostic evaluation revealed the presence of a glomus tumor. A glomus tumor is a rare tumor with a predilection for the hand. Classic symptoms include pain, pain with pressure, and pain with cold temperature. We present a completely updated literature review that addresses the epidemiology, pathology, presentation, diagnostic evaluation, classification, histology, genetics, and treatment options for glomus tumors.     

Comparison of the occlusal vertical dimension after processing complete dentures made with lingualized balanced occlusion and conventional balanced occlusion

STATEMENT OF PROBLEM: An increase in occlusal vertical dimension (OVD) may occur after processing complete dentures. Although many factors that generate this change are known, no information is available in the dental literature regarding the effect that the occlusal scheme may have on the change in OVD. PURPOSE: This in vitro study compared the increase in OVD, after processing, between complete dentures with teeth arranged in lingualized balanced occlusion and conventional balanced occlusion. MATERIAL AND METHODS: Thirty sets of complete dentures were evaluated as follows: 15 sets of complete dentures were arranged in conventional balanced occlusion (control) and 15 sets of complete dentures were arranged in lingualized balanced occlusion. All dentures were compression molded with a long polymerization cycle. The occlusal vertical dimension was measured with a micrometer (mm) before and after processing each set of dentures. Data were analyzed using an independent t test (alpha=.05). RESULTS: The mean increase in the OVD, after processing, was 0.87 +/- 0.21 mm for the control group and 0.90 +/- 0.27 mm for the experimental group. There was no significant difference between the groups. CONCLUSION: After processing, dentures set in lingualized balanced occlusion showed an increase in OVD similar to those set in conventional balanced occlusion. CLINICAL IMPLICATIONS: Although the 2 occlusal concepts resulted in similar increases in the OVD after processing, the lingualized balanced occlusion may result in easier occlusal adjustments, as the less complicated occlusal scheme uses a smaller number of centric occlusion contact points.     

The phenotypic characterization of lymphoid cell subpopulations in gingivitis in children

Phenotypic characterization of lymphoid cell subpopulations in gingivitis associated with the deciduous dentition in children was carried out. Biopsies were obtained from 10 children aged between 5 and 9 years. The tissues were processed for either histochemistry or for immunofluorescence. T-cells were identified by their T-enzyme staining pattern and lack of immunoglobulin. B-cells on the other hand were identified by their lack of T-cell enzymes and presence of surface or cytoplasmic immunoglobulin. Morphologically the lesions consisted of approximately 70 % lymphocytes, between 11 and 26 % macrophages and fewer numbers of polymorphonuclear leukocytes and plasma cells. The majority of lymphocytes (approximately 70 %) were T-enzyme positive/Ig negative indicative of a Tcell population. Approximately 12 % of the infiltrating cells were immunoglobulin positive. These results showed that gingivitis in children is essentially a T-cell lesion and supports the hypothesis that the conversion from a stable to a progressive lesion involves shifts in cell populations.     

A feeding obturator for a preterm baby with Pierre Robin sequence

The article describes a clinical and laboratory technique for the fabrication of a feeding obturator for a baby with Pierre Robin sequence. Emphasis is placed on the direct fabrication of a preliminary custom tray, preventing thermal trauma to the tissues, and overcoming the danger of airway obstruction or foreign body aspiration. The functional problems associated with a cleft palate and various methods to overcome them are also discussed.     

The antimicrobial activity of a dentin conditioner combined with antibacterial agents

Dental hand instruments are not efficient in removing all infected dentin when performing carious removal for minimal intervention techniques. The use of an antibacterial dentin conditioner may therefore be useful when restoring cavities that have residual carious dentin. Antibacterial agents--chlorhexidine hydrochloride, cetylpyridinium chloride, cetrimide, benzaIkonium chloride and sodium hypochlorite, were added either to a dentin conditioner used for glass ionomer cements or distilled water at 1% concentration. Dentin conditioning solutions at pH 2.5, 4.9 and 7.7 were also prepared, along with 1% aqueous thymol. Using an agar diffusion test, 25 microl aliquots were examined for their inhibitory effects on three cariogenic bacteria. After 24 hours, an agar pellet was extracted adjacent to the agar well and placed on a second inoculated agar plate to observe sustained inhibitory effects, after which this procedure was repeated one more time. Antibacterial dentin conditioners showed significant inhibitory effect compared to the control over the three test periods (p<0.016). The combination of dentin conditioners with antibacterial agents significantly reduced the inhibitory effect compared to the antibacterial aqueous solutions (p<0.016). One-percent aqueous thymol showed no inhibitory effect against the test bacteria. The cetrimide-dentin conditioner showed the greatest inhibitory effect against all three test bacteria over the three experimental periods (p<0.016). The inhibitory effect of antibacterial agents was significantly reduced when combined with a dentin conditioner. Only the cetrimide-dentin conditioner combination produced significant inhibitory effects against all three test organisms.     

Serum cytokine levels in periodontitis patients in relation to the bacterial load

Background: Periodontitis is a local inflammatory disease that also has some systemic effects. We investigated the levels of interferon (IFN)‐γ, tumor necrosis factor (TNF)‐α, and interleukin (IL)‐2, ‐4, ‐5, and ‐10 in the serum of patients with periodontitis in relation to the bacterial load in the dental plaques. Methods: Serum cytokine levels in patients with generalized periodontitis and healthy control groups were determined using the cytometric bead array kit. Bacterial load in the dental plaque was determined semiquantitatively by real‐time polymerase chain reaction. The proportions of different lymphocyte subsets were determined in the peripheral blood of patients with periodontitis by flow cytometry. Finally, relationships between the bacterial load in the subgingival plaques of patients with periodontitis and levels of cytokines and counts of lymphocyte subsets were established. Results: Serum levels of IFN‐γ, TNF‐α, and IL‐10 were significantly increased, whereas those of IL‐2 were significantly decreased in patients with periodontitis compared to healthy controls. Increased serum levels of IFN‐γ and TNF‐α in patients with periodontitis were associated with the enhanced dental plaque load with Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) and Porphyromonas gingivalis, respectively. Finally, as revealed by analysis of lymphocyte populations, the presence of A. actinomycetemcomitans and Trepomena denticola was associated with an increased population of CD3^?/CD16⁺ and CD3⁺/CD8⁺ cells, respectively. Conclusion: Certain periodontal pathogens could be associated with an increased level of proinflammatory cytokines in the peripheral blood and thus increased risk of systemic diseases.