A comparative study on the marginal adptation of various prostheses by different impression methods in maxillary central incisor

Abstract

1. Objectives Digital dental impression devices have been introduced to the profession for accurate and convenient treatment. The purpose of this study was to compare the marginal adaptations of the single restorations made by different systems (PFM, Empress-2, CerconⓇ) by different impression systems (conventional impression, digital impression) and evaluate clinical acceptability .

2. Methods The maxillary incisor metal teeth of typodont model was prepared with shoulder margin of 6°taper and used as a master model. As a control group, the prepared metal teeth was impressed conventionally with putty/light body, poured using stone and then working dies were fabricated, 3 times each. As another experimental group, prepared metal teeth was scanned 3 times and produced 3 stereolithographic working dies using the iTero digital system. In each working die of 2 groups, 3 prosthetic copings of different systems (PFM, CerconⓇ, Empress-2) were manufactured. The vertical distance between prosthetic margin and master model adapted with the each prosthetic coping was measured by a stereoscopic microscope (SMZ-U, Nikon, Tokyo, Japan). Along the margin, 25 images were captured and 10 points were measured in each image. On one prosthetic coping, 250 points were measured. Mean and standard deviation were calculated from the total of 4500 data and analyzed statistically using two-sample t-test, one-way ANOVA .

3. Results 1. Mean vertical marginal distance and standard deviations at the marginal opening for the anterior single crowns were 118.7±90.1µm for PFM group, 103.8±78.7µm for Empress-2 group, 120.8±96.5µm for Cercon® made by conventional impression technique. And 108.2±84.9µm for PFM group, 113.5±75.9µm for Empress-2 group, 125.1±91.1µm for Cercon® made by digital impression technique. 2. There was no significant difference found between the conventional impression technique and digital impression technique in the PFM, Empress-2, and Cercon® system (p>0.05). 3. There was no significant difference found among PFM, Empress-2, and Cercon® coping made by conventional impression technique (p>0.05). 4. There was no significant difference found among PFM , Empress-2, and Cercon® coping made by digital impression technique (p>0.05).

4. Conclusion The marginal discrepancies of PFM, Empress-2 and Cercon® copings fabricated by digital impression method were within clinically acceptable standards in addition to conventional impression method.

1. 연구목적

기존 인상채득법에 비해 보다 정확하고 편리한 보철치료를 위하여 최근 디지털 인상채득법이 개발되고 있다. 본 연구에서는 기존 인상채득법과 iTero 디지털 인상채득법으로 제작한 PFM, Empress-2, CerconⓇ coping의 변연적합도를 비교, 분석하여 임상적용의 가능성을 평가하고자 한다.

2. 연구대상 및 방법

typodont의 상악 중절치를 치은연에서 shoulder margin, 12° 경사로 삭제하여 master model을 제작하였다. 기존의 방법으로 인상을 떠서 제작한 작업모형과 i-Tero를 이용해서 제작한 작업모형을 3개씩 제작하고, 각각의 작업모형에서 PFM, Empress-2, CerconⓇ system으로 coping 형태로 총 18개의 보철물을 제작하였다. master model에 제작된 각각의 coping을 적합시킨 상태에서 실체현미경 SMZ-U (NiKon, Tokyo, Japan)을 이용하여 X75 배율로 확대하였다. 현미경에 연결된 카메라와 NIS-ELEMENTS F 2.30 (Nikon, Tokyo, Japan) 프로그램을 이용하여 확대된 변연부를 각 시편 당 25 부위를 무작위로 촬영하고, 각 이미지당 10개 포인트씩 선택하여 모형의 변연과 보철물 변연간의 수직 거리를 계측하였다. 총 750점에서 계측된 데이터에서 평균값과 표준편차를 얻었고, 95% 신뢰수준에서 t-검정과 일원분산배치분석(one-way ANOVA)로 통계 처리하였다.

3. 결과

1. 기존 인상채득법의 변연간격은, PFM군 118.7±90.1µm, Empress-2군 103.8±78.7μm, CerconⓇ 군 120.8±96.5µm이었다. 디지털 인상채득법의 경우 PFM 108.2±84.9μm, Empress-2 113.5±75.9μm, CerconⓇ 125.1±91.1μm 이었다. 2. PFM, Empress-2, CerconⓇ coping의 변연적합도는 기존 방법과 디지털 인상채득법간에 유의한 차이가 없었다(P>0.05). 3. 기존 인상채득법으로 제작한 보철물간의 변연 적합도는 PFM, Empress-2, CerconⓇ coping 모두 유의한 차이가 없었다(P>0.05). 4. 디지털 인상채득법으로 제작한 보철물간의 변연 적합도는 PFM, Empress-2, CerconⓇ coping 모두 유의한 차이가 없었다(P>0.05).

4. 결론

기존 인상채득법과 디지털 인상채득법을 이용하여 제작한 PFM, Empress-2 and Cercon® 보철물의 변연적합도는 모두 임상적으로 받아들일만한 범주 내에 존재하였다.