Endodontics, School of Dentistry, São Paulo State University (UNESP), Araçatuba, SP, Brazil.
Restorative Dentistry, School of Dentistry, Federal University of Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
Clin Oral Investig. 2020 Nov;24(11):3911-3921. doi: 10.1007/s00784-020-03258-9. Epub 2020 Mar 20.
We evaluated the effects of low-level laser therapy (LLLT) using an infrared laser (IRL) and a red laser (RL) on the pulp of molar teeth in rats after dental bleaching to assess inflammation, collagen fiber maturation, and tertiary dentin formation.
Eighty Wistar rats (Rattus norvegicus, albinus) were randomly divided into eight groups with 10 hemimaxillae in each of the following: control; bleached (Ble, 35% hydrogen peroxide [HO]); Ble-1IRL and Ble-1RL (one IRL [808 nm, 30 s, 3 J] or RL [660 nm, 15 s, 1.5 J] application immediately after HO); Ble-3IRL and Ble-3RL (three [immediately, 24 h, and 48 h] IRL or RL applications after HO); and 3IRL and 3RL (three IRL or RL applications without bleaching). The rats were euthanized after 2 and 30 days for histological evaluation of inflammation (hematoxylin-eosin) and maturation of collagen fibers (picrosirius red). Additionally, the dentin deposition in the specimens obtained at 30 days was quantified via microtomography of the pulp chamber volume. Statistical analyses were performed (P < 0.05).
Initially, severe damages to the pulp were observed in the Ble and Ble-1RL groups. Ble-1IRL and Ble-3RL groups showed lower inflammation. The bleached groups had a greater amount of mature collagen fibers than the control group. The Ble-3IRL group had a greater number of immature fibers than the Ble group. At 30 days, there was an absence of inflammation and equal proportion of mature and immature collagen fibers. All bleached groups showed a reduction in the volume of the pulp chamber.
Three consecutive applications of RL and one IRL application can minimize damage to the pulp of bleached teeth, whereas three IRL applications can minimize pulp fibrosis. However, LLLT did not prevent deposition of tertiary dentin.
This study describes LLLT protocols capable of minimizing inflammation and maturation of collagen fibers in pulp tissue after dental bleaching. However, the protocols proved insufficient for reducing the formation of tertiary dentin in bleached teeth.
我们评估了低水平激光疗法（LLLT）使用红外激光（IRL）和红色激光（RL）对牙齿漂白后大鼠磨牙牙髓的影响，以评估炎症、胶原纤维成熟和第三牙本质形成。
80 只 Wistar 大鼠（Rattus norvegicus，白化）随机分为 8 组，每组 10 个半颌，如下：对照组；漂白（Ble，35%过氧化氢[HO]）；Ble-1IRL 和 Ble-1RL（HO 后立即应用一次 IRL[808nm，30s，3J]或 RL[660nm，15s，1.5J]）；Ble-3IRL 和 Ble-3RL（HO 后三次[立即、24 小时和 48 小时]应用 IRL 或 RL）；和 3IRL 和 3RL（三次不漂白的 IRL 或 RL 应用）。在第 2 天和第 30 天，对大鼠进行组织学评估炎症（苏木精-伊红）和胶原纤维成熟（苦味酸天狼星红），然后处死。此外，通过牙髓腔容积的微断层扫描来定量分析 30 天获得的标本中的牙本质沉积。进行了统计学分析（P<0.05）。
最初，Ble 和 Ble-1RL 组的牙髓严重受损。Ble-1IRL 和 Ble-3RL 组的炎症较轻。漂白组的成熟胶原纤维量多于对照组。Ble-3IRL 组比 Ble 组有更多未成熟的纤维。在第 30 天，没有炎症，成熟和未成熟胶原纤维的比例相等。所有漂白组的牙髓腔容积均减少。
连续三次应用 RL 和一次 IRL 应用可最大程度减少漂白牙牙髓的损伤，而三次 IRL 应用可最大程度减少牙髓纤维化。然而，LLLT 不能防止第三牙本质的沉积。
本研究描述了能够在牙齿漂白后最大程度减少牙髓组织炎症和胶原纤维成熟的 LLLT 方案。然而，这些方案对于减少漂白牙中第三牙本质的形成证明是不够的。
