Investigating the histological and radiographic changes of the effect of low-power laser on the pulp revascularization rate of Avulsed immature teeth - an animal study

Dissertation to receive a specialized doctorate degree in pediatric dentistry

Abstract

History and purpose Traumatic dental injuries are considered one of the most common events in childhood and adolescence. Among these injuries, ovalgen (falling out of the tooth from the socket) is considered a real emergency and requires quick and accurate treatment by a dentist, otherwise it can lead to the loss of the patient's tooth, the importance of which multiplies due to the fact that most of these injuries occur in front teeth. Many studies have shown that low power laser, in addition to having soothing and anti-inflammatory properties, increases blood flow and lymphatic drainage in the area and leads to an increase in immune system function and cell proliferation. Therefore, it can effectively improve the healing process. The present study was conducted with the aim of investigating the histological and radiographic changes of the effect of low-power laser on the amount of revascularization of the pulp of avulsed immature teeth. Materials and Methods To conduct the study, 36 immature dog teeth were extracted and randomly and equally divided into 9 groups under reinsertion treatment. In the first group, the teeth were reinserted in the alveolar socket immediately after extraction (4 minutes). In the second group, the teeth were exposed to laser radiation immediately after extraction (4 minutes) and after laser radiation to the alveolar cavity, they were repositioned. In the third group, the teeth were placed in saliva for 30 minutes after extraction and then reinserted. In the fourth group, after being extracted and kept in saliva for 30 minutes, the teeth were subjected to laser radiation and after laser radiation to the alveolar cavity, they were repositioned. In the fifth group, the teeth were placed in water after extraction (30 minutes) and then reinserted. In the sixth group, after being extracted and kept in water for 30 minutes, the teeth were subjected to laser radiation and after laser radiation to the alveolar cavity, they were repositioned. In the seventh group, the teeth were placed in a dry environment after being pulled for 45 minutes and then reinserted. In the eighth group, the teeth were exposed to laser radiation after being extracted and kept in a dry environment for 45 minutes, and after laser radiation to the alveolar cavity, they were repositioned. In the 9th group, after being extracted and stored in a dry environment for 45 minutes, the teeth were exposed to laser radiation and repositioned without laser radiation into the alveolar cavity. In all cases, teeth placement was done according to the latest AAPD protocol. Radiography of the teeth was done before starting work and at intervals of one and two months. Data were analyzed using Fisher's exact test, exact chi-square test, independent t test, and Kruskal-Wallis test. Findings Comparing the use or non-use of laser in groups with different placement conditions, there was no statistically significant difference in terms of the average number of vessels, the type of tumor, the amount of tumor, the percentage of germinal tissue, the percentage of necrosis, the percentage of edema, the percentage of attachment of odontoblasts, the percentage of fibrosis, and the amount of collagen fibers in the two groups. Also, in the radiological evaluation, the use of laser in none of the groups showed a statistically significant difference in terms of the amount of external analysis, internal analysis, and pulp fading as a result of calcification.

Conclusion The use of low-power indium-gallium-aluminum-phosphate laser in the placement process of avulsed immature teeth does not have a significant effect on the prognosis of histological and radiographic recovery of these teeth.

Key words low power laser, pulp revascularization, Avulsed tooth

- Introduction

Traumatic Dental Injuries (TDI) are often caused by falls, and then traffic accidents, violence and sports are among the etiological causes of TDI (1, 2). Boys are twice as likely to have TDI as girls and are more likely to have more than one injury. Also, people with special needs are more prone to TDI (3, 4).

One ??of the most serious dental injuries is avulsion, which refers to the complete displacement of the tooth outside the dental socket. As a result of such injuries, the pulp, periodontal fibers and alveolar bone are severely affected and the nerve-vascular fibers of the tooth and periodontal connections are cut).The pattern of damage to the tooth depends primarily on factors such as 1) impact energy, 2) direction of impact and 3) elasticity of the periodontal structures supporting the tooth, among which the elasticity of the supporting tissues is considered the most important determining factor in the extent (severity) of the damage. Damage to baby teeth due to the elasticity of the bone tissues around the baby teeth usually causes tooth displacement and less hard tissue fracture, but in permanent teeth due to the less elasticity of the tissues around the teeth, the opposite will happen (7). 7-9 years old and seen in the permanent central teeth of the maxilla, because at this age the central teeth are growing, the structures surrounding the tooth are flexible and the periodontal ligaments show very little resistance against extrusive forces (1, 4). in the jaw because they are less protected than other teeth (4, 8). The presence of increased overjet of incisors, anterior open bite and lack of complete coverage of the lips and their failure to meet have been reported as predisposing factors (5, 7). In children with an overjet of more than 3 mm, the probability of this occurrence increases. No relationship has been seen between socioeconomic status and traumatic dental injuries (2). In most cases, the trauma leading to avulsion involves one tooth, but in some cases, avulsion can occur in the form of multiple teeth involvement (9).

The loss of front teeth in children and adolescents due to visible defects causes them to be rejected from the peer group, followed by social exclusion, and feelings of shame and embarrassment while smiling in them, and can cause consequences in communication. by reducing their social function and quality of life (9, 8).

The ideal treatment for an Avulsed tooth is immediate repositioning with an extra-alveolar time of less than 5 minutes. But unfortunately, most Avulsed teeth are replanted with a delay of about 1 hour, and this long extra-alveolar time causes the loss of PDL cells, followed by failure in placement. Current clinical studies show that the failure of replantation treatment during the first 5 years after implantation is approximately 30 to 40%.

Immediate implantation rarely happens due to the factors related to the accident, including the presence of extensive and life-threatening injuries, the patient's emotional state at the time of the injury, or the lack of knowledge and self-confidence of people and even experts about implantation methods (10). Victims of jaw and facial injuries, including dental ovalgen, usually receive first aid from people other than trained dental personnel. Therefore, in most cases, important factors for the success of replantation cannot be controlled. Studies have shown that this scenario can be significantly improved by educating lay people and non-oral health professionals about dentoalveolar trauma and the maintenance environment (medium) to achieve successful treatment.  Immediate tooth replantation leads to better restoration of PDL and significantly reduces the occurrence of root resorption. Therefore, minimizing the time elapsed between trauma and tooth placement and keeping the avulsed tooth in appropriate intermediate environments may reduce the harmful effects of the extra-alveolar period on the root surface and pulpal revascularization and lead to a significant increase in prognosis (11).

Typically, tooth placement occurs within 1 to 4 hours after avulsion, followed by degeneration of PDL cells. It is a common event and the presence of necrotic PDL remnants on the surface of the root will stimulate the occurrence of inflammatory root analysis, which is the main reason for Avulsed tooth loss (11).

To have a good prognosis, an appropriate treatment plan following the injury is of great importance. Although Avulsed tooth placement cannot be done immediately in many cases, it is the treatment of choice for this type of injury. Of course, there are certain conditions in which tooth replantation is not indicated.