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Biomedical subjects

G A Engel

Publications and source records attributed to G A Engel.

3 recordsLinked to original sources
PubMed1979

Preformed arch wires: reliability of fit.

The preformed arch wires currently available are unsuitable for many orthodontic cases, since these arch wires do not take into account all the variations in the size and dimensions of the human arch. In this study, nine theoretical arch wires are derived, based upon two-parameter curves. Tests were conducted which demonstrated that arch wires performed to these nine sets of dimensions would correspond with a reasonable degree of accuracy to a large section of the orthodontic population.

Cephalometry↗
PubMed1979

Soft-tissue change as a result of maxillary surgery. A preliminary study.

A retrospective investigation of soft-tissue changes following two types of maxillary surgical procedure (anterior alveolar segmental, LeForte I) in nineteen adult patients was undertaken. Several hard-tissue coordinates were correlated to each coordinate of eleven soft-tissue points by multivariate regression analysis. This new method was compared to a previously derived nonsurgical prediction method (Ricketts). The following results were observed: 1. For eight horizontal and vertical coordinates (Glh, Glv, Nah, Av, Nch, Ncv, Pnh, and Pnv), neither method was accurate. 2. For ten horizontal and vertical coordinates (Snh, Snv, Ah, Av, ULh, ULv, Stv, LLh, Bv, and Pogv), the mean prediction residuals for the multivariate method were significantly smaller than those for the modified nonsurgical method. 3. For three horizontal and vertical coordinates (LLv, Bh, and Pogh), there were no significant differences between the mean prediction residuals of both methods. Two additional cases were used to test the new method for general applicability. Visual examination reveals that the predictions for these cases are clinicallly acceptable. Only further testing can establish the true validity of the new method.

Adolescent↗