Adequately Prepared? A Study Using an Innovative Computer Application to Measure Clinical Crown Convergence Angles Achieved by Students at a UK Dental School.

This study examined the total occlusal convergence angles created for full coverage crown preparations by students at a UK dental school. Working casts of 82 clinical crown preparations were scanned using a 3D scanner. Stereolithographic files were uploaded to Preppr, a crown preparation analysis application. Mean bucco-lingual convergence angle were 19.6° (+/-11.7) and mesial-distally 17.8° (+/-11.1). Smallest bucco-lingual convergence angles were achieved for canine teeth with the largest on molar teeth. The smallest mesio-distal values were on canine teeth with the largest on molar teeth. Ideal total convergence angles (4-14°) were achieved in 23% of bucco-lingual preparations and 33% of mesio-distal preparation. Results for clinically acceptable angles (10-20°) were 30% and 40% respectively. There were no statistically significant differences between tooth types for mean bucco-lingual values. (p=0.623), mesio-distal mean values were statistically different by tooth type (p=0.003). Mean values for mandibular molars were significantly higher than for maxillary incisors (p=0.001) and mandibular molars had significantly higher values than maxillary canines (p=0.045). Results in this study were comparable to those of other students and qualified clinicians, with a minority of preparation achieving ideal values.

LRRK2 mutations in Parkinson disease.

To determine the frequency of LRRK2 mutations in idiopathic Parkinson disease (PD), the authors studied 786 PD probands, 32 affected siblings, 1,044 unaffected siblings, and 278 unrelated controls. The authors designed allelic discrimination assays for nine LRRK2 mutations and identified these in six probands with PD, one affected sibling, one unaffected sibling, and one unrelated control. Thus LRRK2 mutations only rarely cause idiopathic PD.

Validity of family history data on PD: evidence for a family information bias.

OBJECTIVE: To study the validity of information provided by case and control subjects (or their proxies) about PD among their first-degree relatives. METHODS: Secondary cases of PD were assessed both through a single informant (family history method) and through the study of each relative (family study method). The family study method was considered as the standard for comparison, and the sensitivity and specificity of the family history method were studied. RESULTS: A total of 133 population-based case subjects and their 655 relatives were recruited, and 119 population-based control subjects and their 511 relatives. Sensitivity was 68% (95% CI = 47 to 85) for cases and 45% (95% CI = 17 to 77) for controls. Specificity was 99% (95% CI = 98 to 99) for cases and 100% (95% CI = 99 to 100) for controls. The odds ratio (OR) for family history of PD was 4.34 (95% CI = 1.63 to 11.58, p = 0.003) using the family history method and 1.86 (95% CI = 0.78 to 4.44, p = 0.16) using the family study method. The former significant OR more than doubled the latter not significant OR (relative bias = 133%). Bias was more pronounced for proxy interviews and for women informants, and when the relatives were siblings, were living, and were examined or had medical record documentation. CONCLUSIONS: Case subjects with PD (or their proxies) are more aware of PD among their first-degree relatives than control subjects (or their proxies); however, they overreport PD in relatives who are not affected. This causes a substantial family information bias.

A limited role for DJ1 in Parkinson disease susceptibility.

An association study of four common polymorphisms in the DJ1 gene and Parkinson disease (PD) was conducted. PD probands were compared with their unaffected siblings matched by gender and closest age at study (416 vs 416) and with unrelated control subjects (691 vs 190). None of the four haplotype tagging single-nucleotide polymorphisms (SNPs) was associated with PD overall, but SNP1 (position 4,345 bp) and SNP3 (position 16,491 bp) were associated with PD in women (p = 0.03 and p = 0.002).