A J Drinnan

Bio: A J Drinnan is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 10 citations.

A diagnostic craniometric method for determining occlusal vertical dimension

Abstract: There is no precise scientific method for determining the correct edentulous occlusal vertical dimension. This study established the proportion between the ear-eye to chin-nose distance for determining reasonable occlusal vertical dimension. Two hundred white and 400 Asian men and women participated in this study. The ear-eye and chin-nose distances were measured with a modified craniometer. The results revealed that left ear-eye distance can be used to predict chin-nose distance with reasonable accuracy. However, the algorithm for making this prediction is not the same for combinations of sex and ethnic origin.

Mandibular Full-Arch Fixed Prostheses Supported on 4 Implants with Either Axial Or Tilted Distal Implants: A 3-Year Prospective Study

Abstract: Purpose This prospective study evaluated the clinical and radiographic outcome of distally cantilevered 4-implant-supported fixed mandibular prostheses (4-ISFMP) with distal implants either in axial or distally tilted direction. Material and Methods Forty-one mandibulary edentulous patients received acrylic veneered 4-ISFMP with casted framework. Based on distal implant placement direction patients were assigned to 2 groups: 21 patients with four (2 anterior/2 posterior) axial implants (axial-group I) and 20 patients with 2 anterior axial/2 distal tilted implants (tilted-group II). Patients were prospectively followed for 3 years by annual examinations of implants and prosthetic survival rates including assessment for biological and mechanical complications. Additionally, peri-implant marginal bone resorption [MBR], pocket depth [PD], plaque index [PI], bleeding index [BI] and gingival index [GI], and calculus index [CI] were evaluated at each annual follow-up. Results 37/41 patients (19 axial-group I, 18 tilted-group II) and 148/164 implants were followed at the 1-, 2-, and 3-year evaluation (dropout rate: 11.8%) presenting no implant and denture loss (100% survival). The overall, MBR at year 1, 2, and 3 was 1.11 ± 0.4 mm, 1.26 ± 0.42 mm, and 1.40 ± 0.41 mm, respectively, representing a significant (p < .001) continuing time depending annual reduction. MBR and PD did not differ between anterior and posterior regions in both groups or for anterior and posterior regions between the groups. PI and CI were significantly (p < .001) higher for implants in anterior regions than for posterior regions in both groups. Moreover, posterior implant regions showed significantly (p < .001) higher PI and CI for axial-group I than for tilted-group II over time. Biological and mechanical complications as well as GI and BI did not differ between the groups over a 3-year follow-up period. Conclusion For clinical implant and prosthesis outcome no statistical significant mean differences were noted for distally cantilevered 4-ISFMP supported by distal implants placed in tilted or axial direction.

Effects of relief space and escape holes on pressure characteristics of maxillary edentulous impressions.

Abstract: Statement of problem The selective pressure technique has been recommended for making impressions of maxillary edentulous residual ridges. Although various methods for making impressions have been reported, a definitive procedure has not been clearly elucidated. Purpose This in vitro study evaluated changes in impression pressure produced by different types of relief space and escape holes in the impression tray for making an impression of a simulated maxillary edentulous arch. Material and methods Silicone impression material (Exadenture) and a maxillary edentulous acrylic cast were used. A miniature pressure sensor was embedded at the mid-palatal suture (point-P) and at the left first molar area on the edentulous ridge (point-R). Three types of tray relief were used: no spacer (NS), a 0.36-mm-thick sheet of wax (SS), or a 1.40-mm-thick base plate wax (BS). Four types of escape holes were made: no hole (NH), or escape holes of 0.5, 1.0, or 2.0 mm in diameter (05H, 10H, and 20H, respectively) in the area opposing point-P. Twelve trays were formed using these relief space and escape hole combinations. The cast and tray were attached to a rheometer for applying a continuous isotonic force of 5.0 kgf and compressive speed of 120 mm/min. Impressions were made and measurement of pressure (kPa) began immediately prior to compression and continued until the materials had polymerized for 2 minutes, with a sampling time of 5 Hz. Measurements were performed 5 times for each tray. The data were analyzed using 3-way analysis of variance and the Bonferroni test (α=.05). Results At initial pressure, the data obtained at point-P showed significantly higher values for NSNH, NS05H, SSNH, and SS05H (range: 22.29 ± 1.58 kPa to 29.96 ± 1.41 kPa) than those at point-R (range: 18.61 ± 1.12 kPa to 22.71 ± 2.11 kPa). At end pressure, the data obtained from NSNH at point P showed a significantly higher value (25.36 ± 1.69 kPa) than that of point-R (15.36 ± 0.99 kPa) ( P P Conclusion For making impressions of an edentulous maxilla, the data suggest that a tray with an escape hole 1.0 mm or larger or a spacer thickness of base plate wax (1.40 mm) be used.