Photobiomodulation Activates Microglia/Astrocytes and Relieves Neuropathic Pain in Inferior Alveolar Nerve Injury.

Objective: This study aimed to determine microglial/astrocyte changes and their associated analgesic effect in inferior alveolar nerve injury (IANI) model rats treated with photobiomodulation therapy (PBMT) using a 940-nm diode laser. Background: Very few basic studies have investigated microglial/astrocyte dynamics following PBMT aimed at relieving neuropathic pain caused by IANI. Methods: Rats were divided into an IANI-PBM group, IANI+PBM group, and sham+PBM group. Observations were made on the day before IANI or the sham operation and on postoperative days 3, 5, 7, 14, and 28. PBMT was delivered for 7 consecutive days, with an energy density of 8 J/cm2. Behavioral analysis was performed to determine pain thresholds, and immunohistological staining was performed for the microglia marker Iba1 and astrocyte marker glial fibrillary acidic protein, which are observed in the spinal trigeminal nucleus. Results: Behavioral analysis showed that the pain threshold returned to the preoperative level on postoperative day 14 in the IANI+PBM group, but decreased starting from postoperative day 1 and did not improve thereafter in the IANI-PBM group (p ≤ 0.001). Immunological analysis showed that microglial and astrocyte cell counts were similar in the IANI+PBM group and IANI-PBM group shortly after IANI (day 3), but the expression area was larger (p ≤ 0.001) and hypertrophy of microglia and astrocyte cell bodies and end-feet extension (i.e., indicators of activation) were more prominent in the IANI+PBM group. Conclusions: PBMT after IANI prevented hyperalgesia and allodynia by promoting glial cell activation shortly after injury.

CO2 Laser for Esthetic Healing of Injuries and Surgical Wounds with Small Parenchymal Defects in Oral Soft Tissues.

A number of studies have recently demonstrated the effectiveness of CO2 laser irradiation for the repair and regeneration of scar tissue from injuries or surgical wounds. However, such studies of the oral mucosa are highly limited. Previous studies using CO2 laser irradiation have indicated that two factors contribute to esthetic healing, namely, artificial scabs, which are a coagulated and carbonized blood layer formed on the wound surface, and photobiomodulation therapy (PBMT) for suppressing wound scarring and promoting wound healing. This review outlines basic research and clinical studies of esthetic healing with the use of a CO2 laser for both artificial scab formation by high-intensity laser therapy and PBMT in the treatment of injuries and surgical wounds with small parenchymal defects in oral soft tissues. The results showed that the wound surface was covered by an artificial scab, enabling the accumulation of blood and the perfusion necessary for tissue regeneration and repair. Subsequent PBMT also downregulated the expression of transformation growth factor-b1, which is involved in tissue scarring, and decreased the appearance of myofibroblasts. Taken together, artificial scabs and PBMT using CO2 lasers contribute to the suppression of scarring in the tissue repair process, leading to favorable esthetic and functional outcomes of wound healing.

A narrative review and clinical anatomy of herpes zoster infection following COVID-19 vaccination.

INTRODUCTION: In this review, cases of herpes zoster (HZ) infection following receipt of COVID-19 vaccines will be analyzed. We also present two cases of oral HZ following the COVID-19 vaccine and discuss this clinical anatomy. MATERIALS AND METHODS: A database search using PubMed was conducted in August 2021 and 20 articles were found to be eligible for review. Patient data and vaccine information were analyzed. In addition, two cases of oral HZ infection following the receipt of COVID-19 vaccines are presented. RESULTS: A total of 399 cases were identified. The affected dermatomes mimicked the regular distribution of HZ. For the dermatomes of the face, the various reports used different ways to describe the areas involved; CNV, CNV1, CNV2, CNV3, lower jaw, forehead, and under the eyebrow (CNV, 2 cases; CNV1, 4 cases; CNV2, 3 cases; and CNV3, 3 cases). Some patients who had a history of varicella zoster virus vaccination had HZ following the COVID-19 vaccination. Two patients with oral HZ following vaccination were found to have involvement of the greater palatine nerve. CONCLUSIONS: Vaccine-related HZ cases have been reported worldwide. Although many studies with a larger number of cases are ongoing, detailed information can be obtained from case reviews as reported herein.

Oral Herpes Zoster Infection Following COVID-19 Vaccination: A Report of Five Cases.

Recently, two cases of oral herpes zoster (HZ) following COVID-19 vaccines were reported. It was suggested that COVID-19 vaccine-related oral HZ cases might be missed or misdiagnosed as stomatitis or isolated oral herpes. In this report, five cases of oral HZ following COVID-19 vaccinations are presented. Four cases were observed on the hard palate (V2), and one case was found on the mandible (V3). Four patients did not receive any treatment for their oral HZ, but one patient also had skin reactions on her right orbit and ear and was thus treated with an antiviral drug. As these cases were seen during such a short period of time and in one practice, the relationship with the COVID-19 vaccination appears to be related.

Healing of Open Upper Lip Vermillion Wounds Irradiated with CO2 Laser Immediately After Injury.

Objective: To evaluate the healing of open upper lip vermillion wounds irradiated with CO2 laser immediately after injury. Background: There are reports of using CO2 laser therapy on healed wounds for scar tissue reduction. However, limited data exist regarding its use immediately after an injury. Thus, the role of CO2 laser in wound healing remains unclear. Methods: Two patients with open upper lip vermillion wounds were treated using CO2 laser irradiation to the area postsuturing. Results: Good functional and aesthetic results were obtained from the therapy, with no postoperative pain complaints or infection. Conclusions: CO2 laser irradiation, performed immediately after an injury, could be an effective treatment option for open vermillion wounds.

Wound Healing and Cell Dynamics Including Mesenchymal and Dental Pulp Stem Cells Induced by Photobiomodulation Therapy: An Example of Socket-Preserving Effects after Tooth Extraction in Rats and a Literature Review.

High-intensity laser therapy (HILT) and photobiomodulation therapy (PBMT) are two types of laser treatment. According to recent clinical reports, PBMT promotes wound healing after trauma or surgery. In addition, basic research has revealed that cell differentiation, proliferation, and activity and subsequent tissue activation and wound healing can be promoted. However, many points remain unclear regarding the mechanisms for wound healing induced by PBMT. Therefore, in this review, we present an example from our study of HILT and PBMT irradiation of tooth extraction wounds using two types of lasers with different characteristics (diode laser and carbon dioxide laser). Then, the effects of PBMT on the wound healing of bone tissues are reviewed from histological, biochemical, and cytological perspectives on the basis of our own study of the extraction socket as well as studies by other researchers. Furthermore, we consider the feasibility of treatment in which PBMT irradiation is applied to stem cells including dental pulp stem cells, the theme of this Special Issue, and we discuss research that has been reported on its effect.