Odontoblast responses to GaAlAs laser irradiation in rat molars: an experimental study using heat‐shock protein‐25 immunohistochemistry

Abstract

Pulpal responses to gallium-aluminum-arsenide (GaAlAs) laser irradiation applied to the tooth remains to be elucidated. This study aimed to evaluate the effect of the GaAlAs laser on odontoblasts using immunohistochemistry for heat-shock protein (HSP)-25, which labels mature and newly differentiated odontoblasts. The mesial surface of the upper right first molar of 8-wk-old Wistar rats was lased at an output power of 0.5-1.5 W for 180 s. The animals were perfusion-fixed at intervals of 6 h to 30 d after irradiation. At 6 h to 7 d, the intensity of HSP-25-immunoreactivity was found to be disturbed in the coronal odontoblast-layer in an energy-dependent manner. At 30 d, tertiary dentin with/without bone-like tissue was formed abundantly in the dental pulp. Statistical analysis revealed that the area occupied by the new hard tissues was significantly wider in 1.5 W-lased specimens than in 0.5 W-lased specimens. An intense HSP-25 immunoreactivity was seen in the odontoblasts underlying the tertiary dentin, whereas immunoreactivity was weak around the bone-like tissue. It was concluded that the GaAlAs laser may induce the formation of tertiary dentin by influencing the secretory activity of odontoblasts. However, higher energies may cause irreversible changes to the pulp, often leading to the formation of an intrapulpal bone-like tissue.

Low-level (gallium-aluminum-arsenide) laser irradiation of Par-C10 cells and acinar cells of rat parotid gland

“…Many studies have investigated low-level laser irradiation in various types of cell, including fibroblasts [23], dental pulp cells [33], periodontal ligament cells [22] and ectoblastic cells [17]. A few studies have also investigated the influence of low-level laser irradiation on salivary gland cells [9][10][11][12][13].…”

“…Many investigations using low-level laser irradiation have been reported in various cells and tissues [5,17,22,23,33], with irradiation energy ranging from 0.1 to10 J/cm 2 . The Ga-Al-As diode laser device used in this study is capable of a higher output power than other similar devices.…”

Current Uses of Diode Lasers in Dentistry

“…The histological changes of the pulp observed from the previous studies without standardizing the exposure time were periapical abscess; dentin bridge formation, necrosis, carbonization, inflammatory infiltration, odema and haemorrhage were observed [11][12][13][14][15]. Hence the histological response of the pulp to 810 nm diode laser at 2 W power setting and 1 s, 3 s and 5 s exposure time in dog's teeth was evaluated.…”

Low Level Laser Applications in Periodontology

“…DH'de DDLT'yi takiben ağrı azalmasında çeşitli mekanizmalar açıklanmıştır. Üçünce derece dentinlerin oluşumu ve hassas sinir aktivasyonundaki azalma gibi pozitif etkileri üzerinde durulmaktadır (60). Nörofizyolojik mekanizmadaki bilgiler ise hala yetersizdir, DDLT, C-fibril ileticilerinde depolarizasyonu etkileyerek analjezik etki sağlar.…”