象牙質即時封鎖と即日出荷によるセラミックオーバーレイの破折強度

Fracture strength of ceramic overlays with immediate dentin sealing and same-day delivery.

抄録

象牙質即時封鎖法（IDS）の試験管内での利点として報告されている、歯質に対する接着強度の向上が、即日（SD）歯科治療の時代にも得られるかどうかを評価する研究は限られている。本研究の目的は，1時間SDまたは2週間MDの条件下で，遅延象牙質シーリング法（DDS法）または即時象牙質シーリング法（IDS法）を用いて作製したセラミックオーバーレイの破折強さを比較することである．40本の健康な上顎第三大臼歯を抜歯し，二ケイ酸リチウムオーバーレイ修復のために準備し，10本ずつ4群に分けた．SD-DDS群では、歯牙を調製後、人工唾液中で1時間保存し、セラミックオーバーレイのデリバリー時に接着プロトコール（接着剤とレジンセメント）を塗布した。SD-IDS群では、歯牙を準備し、接着プロトコルを直ちに適用し、オーバーレイを提供する前に歯牙を1時間保存した。MD-DDS群およびMD-IDS群のプロトコールは、オーバーレイを提供する前に歯をプロビジョナライズし、2週間保存した以外は、それぞれSD-DDS群およびSD-IDS群と同じであった。試験片は、口蓋咬頭の頬側傾斜部にロッドを置き、万能試験機で破壊まで荷重をかける前に、サーモサイクルを行い、周期的な機能的荷重をかけた。二元配置分散分析試験の結果、象牙質封鎖（P = 0.331）または送達時間（P = 0.314）に基づく群間における破折強度の統計的有意差は認められなかった。セラミックの一部が破折し、歯は無傷であった場合と、セラミックと歯の一部が破折した場合である。破折試験中に修復物自体が剥離した例はなかった。Kruskal-Wallis検定の結果、破折様式に統計的に有意な差は認められませんでした。このin vitro試験において、IDSはDDSと比較して、オーバーレイ修復物の破折強度を有意に増加させませんでした。

Limited research is available evaluating whether the reported in vitro benefit of immediate dentin sealing (IDS)-namely, increased bond strength to tooth structure-can be acquired in the era of same-day (SD) dentistry. The purpose of this study was to compare the fracture strengths of ceramic overlays fabricated with a delayed dentin sealing (DDS) technique or an IDS technique under 1-hour SD or 2-week multiple-day (MD) delivery conditions. Forty extracted, healthy maxillary third molars were prepared for a lithium disilicate overlay restoration and divided into 4 groups of 10 teeth each. In the SD-DDS group, the teeth were prepared and then stored for 1 hour in artificial saliva, and the adhesion protocol (bonding agent and resin cement) was applied at the time of delivery of the ceramic overlay. In the SD-IDS group, the teeth were prepared, the adhesive protocol was applied immediately, and the teeth were stored for 1 hour before delivery of the overlay. The protocols for the MD-DDS and MD-IDS groups were identical to SD-DDS and SD-IDS, respectively, except that the teeth were provisionalized and stored for 2 weeks prior to delivery of the overlay. Specimens were thermocycled and subjected to cyclic functional loading before they were loaded to failure in a universal testing machine using a rod resting on the buccal incline of the palatal cusp. Two-way analysis of variance tests revealed no statistically significant differences in fracture strength between the groups based on dentin sealing (P = 0.331) or delivery time (P = 0.314). The specimens demonstrated 2 fracture types; either a portion of the ceramic cohesively fractured, leaving the tooth intact, or the ceramic and part of the tooth fractured. There were no instances in which the restoration itself delaminated during fracture testing. A Kruskal-Wallis test indicated there were no statistically significant differences in fracture modes between the groups. In this in vitro study, IDS did not provide a significant increase in the fracture strength of overlay restorations compared with DDS, regardless of whether the restorations were delivered the same day or after 2 weeks of storage.