Veerabadhran M M, Reddy V, Nayak U A, Rao A P, Sundaram M A
Department of Pedodontics and Preventive Dentistry, Vivekananadha Dental College and Hospital for Women, Trichengode, India.
J Indian Soc Pedod Prev Dent. 2012 Jan-Mar;30(1):19-26. doi: 10.4103/0970-4388.95570.
This in vitro study was conducted to find out the effect of retentive groove, sand blasting and cement type on the retentive strength of stainless steel crowns in primary second molars.
Thirty-two extracted intact human maxillary and mandibular primary second molars were embedded in aluminum blocks utilizing autopolymerising acrylic resin. After tooth preparation, the 3M stainless steel crown was adjusted to the prepared tooth. Then weldable buccal tubes were welded on the buccal and lingual surfaces of each crown as an attachment for the testing machine. A full factorial design matrix for four factors (retentive groove placement on the tooth, cement type, sandblasting and primary second molar) at two levels each was developed and the study was conducted as dictated by the matrix. The lower and upper limits for each factor were without and with retentive groove placement on the tooth, GIC and RMGIC, without and with sandblasting of crown, maxillary and mandibular second primary molar. For those teeth for which the design matrix dictated groove placement, the retentive groove was placed on the middle third of the buccal surface of the tooth horizontally and for those crowns for which sandblasting of the crowns are to be done, sandblasting was done with aluminium oxide with a particle size of 250 mm. The crowns were luted with either GIC or RMGIC, as dictated by the design matrix. Then the retentive strength of each sample was evaluated by means of an universal testing machine. The obtained data was analyzed using ANOVA for statistical analysis of the data and 't'- tests for pairwise comparison.
The mean retentive strength in kg/cm 2 stainless steel crowns luted with RMGIC was 19.361 and the mean retentive strength of stainless steel crowns luted with GIC was 15.964 kg/cm 2 with a mean difference of 3.397 kg/cm 2 and was statistically significant. The mean retentive strength in kg/cm 2 of stainless steel crowns, which was not sandblasted, was 18.880 and which was sandblasted was 16.445 kg/cm 2 with a mean difference of 2.436 kg/cm 2 . These results were again statistically significant.
It was found that the crowns luted with resin-modified glass ionomer cements (RMGIC's) offered better retentive strength of crowns than glass ionomer cements (GIC) and stainless steel crowns which were cemented without sandblasting showed higher mean retentive strength than with sandblasting of crowns. The presence of groove did not influence the retentive strength of stainless steel crowns.
本体外研究旨在探究固位沟、喷砂处理及粘结剂类型对乳磨牙不锈钢全冠固位强度的影响。
32颗完整拔除的人上颌和下颌乳磨牙，采用自凝丙烯酸树脂包埋于铝块中。牙体预备后，将3M不锈钢全冠适配于预备好的牙齿。然后在每个全冠的颊面和舌面焊接可焊接颊管，作为测试机的附着点。设计了一个二水平四因素（牙体上固位沟的设置、粘结剂类型、喷砂处理和乳磨牙）的全因子设计矩阵，并按矩阵要求进行研究。每个因素的下限和上限分别为牙体上无固位沟和有固位沟、玻璃离子水门汀（GIC）和树脂改性玻璃离子水门汀（RMGIC）、全冠无喷砂和有喷砂、上颌和下颌第二乳磨牙。对于设计矩阵要求设置沟的牙齿，在牙体颊面中1/3水平放置固位沟；对于要求进行全冠喷砂的全冠，采用粒径为250μm的氧化铝进行喷砂。根据设计矩阵，全冠分别用GIC或RMGIC粘结。然后用万能试验机评估每个样本的固位强度。使用方差分析对获得的数据进行统计分析，并使用“t”检验进行两两比较。
用RMGIC粘结的不锈钢全冠平均固位强度为19.361kg/cm²，用GIC粘结的不锈钢全冠平均固位强度为15.964kg/cm²，平均差值为3.
