الفهرس 
REFERENCESOnly 14 pages are availabe for public view
 |  | from | 124 |  |  |
| | | from | 124 | | |
Abstract
This study was conducted to evaluate and compare the use of two different materials; zirconia and metal, for the construction of primary copings for telescopic mandibular overdenture.
Six patients having maxillary completely edentulous arch, and mandibular remaining bilateral cuspids with adequate bone support, not less than two thirds of the root, free from gingival or periodontal inflammations or any systemic diseases affecting bone, were selected for this study.
Split-mouth design was used; each patient received the two tested materials, one side restored with CAD/CAM zirconia, and the other side with metal primary coping. Secondary copings were metal in both sides. Maxillary complete denture and mandibular telescopic acrylic overdenture were constructed by the conventional way, after processing, direct pick-up of the secondary metal copings was done.
Abutment teeth were examined clinically by the following parameters; Plaque index (PI), Gingival index (GI), Periodontal probing pocket depth (PPD), Clinical attachment level (CAL), and Tooth mobility; to indicate the mucosal and periodontal health around them. Clinical evaluation was done immediately after overdenture insertion, after one, and three months.
Clinical results showed that after three months, there was statistical significant increase in all parameters around metal than zirconia primary coping. There was absence of mobility in all abutment teeth.
Radiographic evaluation to assess changes in the level of the alveolar bone around each abutment was performed immediately following overdenture insertion, and six months later, using radiovisiography (RVG) and SIDEXIS image processing program to obtain standardized digital periapical x-ray films.
Radiographic results revealed mild bone loss, less than 0.7mm after 6months in both sides; this was almost equal in mesial and distal sides of each tooth. However, bone loss around abutments covered by metal coping was more than that covered by zirconia; the results being statistically significant.
Conclusions
• Zirconia primary coping is associated with superior clinical parameters than metal. It has lower plaque adherence affinity, stabilizes soft tissue and crestal bone level.
• Both primary copings were associated with little amount of bone loss, which is clinically acceptable, and in favor of zirconia.
• Construction of telescopic overdenture with primary zirconia copings maintains the periodontal health of abutment teeth. However, patient selection, oral hygiene instructions, and regular check up are very important for its success in most patients.