Root canal shaping with manual stainless steel files and rotary Ni-Ti files performed by students.

AIM: To investigate root canal shaping with manual stainless steel files and rotary Ni-Ti files by students. METHODOLOGY: Two hundred and ten simulated root canals with the same geometrical shape and size in acrylic resin blocks were prepared by 21 undergraduate dental students with manual stainless steel files using a stepback technique or with rotary Ni-Ti files in crown-down technique. Preparation length, canal shape, incidence of fracture and preparation time were investigated. RESULTS: Zips and elbows occurred significantly (P < 0.001) less frequently with rotary than with manual preparation. The correct preparation length was achieved significantly (P < 0.05) more often with rotary Ni-Ti files than with manual stainless steel files. Fractures occurred significantly (P < 0.05) less frequently with hand instrumentation. The mean time required for manual preparation was significantly (P < 0.001) longer than that required for rotary preparation. Prior experience with a hand preparation technique was not reflected in an improved quality of the subsequent engine-driven preparation. CONCLUSIONS: Inexperienced operators achieved better canal preparations with rotary Ni-Ti instruments than with manual stainless steel files. However, rotary preparation was associated with significantly more fractures.

Association of short-term response to haloperidol treatment with a polymorphism in the dopamine D(2) receptor gene.

OBJECTIVE: Pharmacogenetic influences on therapeutic response to neuroleptic treatment are poorly understood. This study investigates the association of response to short-term haloperidol treatment with a Taq I polymorphism in the DRD2 gene. METHOD: Fifty-seven patients with acute psychosis were treated with haloperidol for up to 28 days. Improvement and response were measured by using the Positive and Negative Syndrome SCALE: Forty-one patients were homozygous for allele 2, and 16 were heterozygous. RESULTS: Heterozygous patients showed a greater improvement in positive, but not in negative, symptoms on all treatment days than patients homozygous for allele 2. Differences in improvement of positive symptoms reached statistical significance on days 14, 21, and 28. On treatment day 14, 10 (62.5%) of 16 heterozygous patients had at least 50% improvement of positive symptoms, compared with 11 (28.9%) of 38 homozygous patients. CONCLUSIONS: These results support the hypothesis that genetic variations in the DRD2 gene may influence the individual response to antipsychotics.