Marginal and Internal Gaps, Surface Roughness and Fracture Resistance of Provisional Crowns Fabricated With 3D Printing and Milling Systems.

PURPOSE: To compare the marginal and internal gap, surface roughness, fracture resistance and mode of failure of provisional crowns fabricated with 3D printing and CAD/CAM manufacturing techniques. Methods and Materials: A maxillary first premolar was prepared for an all-ceramic crown and reproduced in cobalt-chromium metal dies (n=30) following CAD/CAM technology. The die was digitally scanned and exocad software was used to design the missing crown, which was manufactured using a CAM milling machine and two types of 3D printing machines (SLA and DLP) to produce 10 provisional crowns per group. The crowns were cemented to their respective dies and stored in water (24 hours; 37°C) followed by 600 thermal cycles (5°C/55°C) and 100,000 mechanical cycles (at 50N). Marginal and internal gap measurements were carried out using a 3D superimposition technique. Surface roughness (Ra) was determined using a profilometer at 0.5 mm/ second cross-head speed. The crowns were loaded to fracture at 0.5 mm/minute cross-head speed. Fracture forces and mode of failure were recorded, and data were analyzed using one-way analysis of variance (ANOVA) and multiple comparisons post hoc tests (p<0.05). RESULTS: The SLA group exhibited higher marginal and internal gaps than both the CAD/CAM and DLP groups (p<0.05). The DLP group showed higher surface roughness than the CAD/CAM and SLA groups (p<0.01). The CAD/CAM and SLA groups showed higher resistance to fracture than the DLP (p<0.05) group. Mode of failure I: Minimal crown fracture or crack, was predominate among DLP and SLA crowns (60%), while the Mode II: Less than half of the crown lost, was predominant among CAD/CAM crowns (60%). CONCLUSIONS: Crowns manufactured following CAD/CAM technique have better marginal and internal fit, surface roughness than SLA and DLP crowns. The CAD/CAM and SLA crowns showed higher resistance to fracture than the DLP crowns.

[Fine-needle aspiration (FNA) of the thyroid gland : Analysis of discrepancies between cytological and histological diagnoses]. / Feinnadelaspiration (FNA) der Schilddrüse : Analyse diskrepanter zytologischer und histologischer Diagnosen.

BACKGROUND: Diagnostic problems of thyroid cytology are frequently discussed, but relevance and causes of discrepant cytological and histological diagnoses are rarely studied in detail. OBJECTIVES: Investigation of causes and relevance of discrepant diagnoses. MATERIALS AND METHOD: The analysis includes 297 patients who had thyroid resection after prior fine needle aspiration (FNA) and is based on the cytological and histological reports. In special cases, cytological and histological specimens were re-examined. RESULTS: Malignant tumors were found in 45 patients (15.1 %). In 5 patients the cytological diagnosis was "false negative". Three of these 5 tumors were papillary carcinomas (PTC) of ≤10 mm, one an obviously nonmalignant papillary proliferation of the thyroidal epithelium and one a malignant lymphoma complicating autoimmune thyreoiditis (AIT). In 11 of the 35 patients with a FNA diagnosis "suspicious of malignancy" or "malignant," 1 AIT, 4 goiter nodules, and 6 adenomas were diagnosed histologically. However, since distinct nuclear atypia was found in three of five false positive diagnoses, there still remains doubt in their benignity. CONCLUSIONS: Carcinomas of ≤10 mm incidentally detected in the resected thyroid tissue may not be relevant to the patient and do not reduce the high negative predictive value of FNA. The final diagnosis on the resected tissue should include the cytological findings. Discrepant findings should be commented in the report to the clinician.

Aggressive strategic planning for oral health in Kuwait: a decade of post-war successes.

Strategic planning and implementation of oral health care and disease prevention programmes after the 1990/91 Gulf war are discussed. The key concept was to develop access to care and disease prevention for all Kuwaiti children in government kindergarten/primary schools and to eliminate emphasis on extractions and restorations. Resources were restored to pre-war levels and then increased. Prevention programmes for 150 000 children were established. Prevention funds increased from 7% to 20% of the oral health budget. Prevention-based dentists increased from 9.7% to 28.0% of staff. Rising caries trends were stabilized or reduced by up to 36.8%. Percentage of caries-free primary dentition in children increased up to 37.6%, permanent dentition up to 27.0%. A dentistry school was established.

Aggressive strategic planning for oral health in Kuwait: a decade of post-war successes

Strategic planning and implementation of oral health care and disease prevention programmes after the 1990/91 Gulf war are discussed. The key concept was to develop access to care and disease prevention for all Kuwaiti children in government kindergarten/primary schools and to eliminate emphasis on extractions and restorations. Resources were restored to pre-war levels and then increased. Prevention programmes for 150 000 children were established. Prevention funds increased from 7% to 20% of the oral health budget. Prevention-based dentists increased from 9.7% to 28.0% of staff. Rising caries trends were stabilized or reduced by up to 36.8%. Percentage of caries-free primary dentition in children increased up to 37.6%, permanent dentition up to 27.0%. A dentistry school was established