A systematic review of factors impacting intraoral scanning accuracy in implant dentistry with emphasis on scan bodies.

PURPOSE: The purpose of this systematic review was to explore and identify the factors that influence the accuracy of intraoral scanning in implant dentistry, with a specific focus on scan bodies (ISBs). METHODS: Following the PRISMA 2020 guidelines, this study conducted a thorough electronic search across MedLine, PubMed, and Scopus to identify relevant studies. Articles were screened based on titles, abstracts, and full texts for relevance. The Robins I tool assessed the risk of bias in various study types. Data extraction occurred based on predetermined parameters for studying specimens and assessing outcomes. RESULTS: 16 studies met the specified criteria and were consequently included in the systematic review. Due to variations in variables and methods across the selected studies, statistical comparison of results was not feasible. Therefore, a descriptive review approach was chosen, acknowledging the substantial heterogeneity in the reviewed literature. CONCLUSIONS: The precision of virtual scan results is contingent upon diverse characteristics of ISBs and implants. These factors encompass their placement within the dental arch, structural design, shape, material composition, color, and the manufacturing system, all of which contribute to scan accuracy. Additionally, considerations such as the intraoral scanner (IOS) type, scanning technique, use of scan aids, inter-implant distance, scan span, and the number of implants warrant evaluation. In the context of capturing implant positions, intraoral scanning with ISBs demonstrates comparable accuracy to traditional impression methods, particularly in single and short-span scenarios. However, the existing data lacks sufficient information on in vivo applications to formulate clinical recommendations.

Comparison of Stress Distribution in Alveolar Bone with Different Implant Diameters and Vertical Cantilever Length via the Finite Element Method.

Available bone is one of the important factors in implant treatments. Due to concerns about complications caused by less bone implant contact area, researchers have focused on biomechanical properties of implants and methods to promote them. We investigated stress distribution around bone of different implant diameters and vertical cantilever length. Computed tomography (CT) images obtained of human mandible were used in this study. An SPI implant (Alpha Bio Tech, Simplantology) of two different lengths (10.5 mm and 8.5 mm) and two different widths (3.5 mm and 4.5 mm) were placed into two different groups of bone samples (with and without osteoplasty). Vertical and lateral forces of 100N and 30N at 45° were applied simultaneously in two models. The stress was analyzed using the finite element method. Maximum stress areas were located around the implant neck. Lower stress values in the loaded implants were observed in the shorter group related to the increase in crown height space, when compared to the other group. A wider implant may be better to dissipate force, thus reducing stress on the bone surrounding the implant. Additionally, the use of shorter and wider implants might be a reasonable alternative in sites limited by the height of the residual ridge.

The effects of diode laser (660 nm) on the rate of tooth movements: an animal study.

Low-level laser has been indicated to have the capability to facilitate the differentiation of the osteoclastic and osteoblastic cells which are responsible for the bone remodeling process. The aim of this study was to evaluate the effects of InGaAlP laser with a wavelength of 660 nm on the rate of tooth movement and histological status. Thirty male Wistar rats of 7 weeks old were selected for this study. The rats were randomly divided into two groups of 15 each to form the experimental (laser-irradiated) and control (non-irradiated) groups. The control group received unilateral orthodontic appliance design (one quadrant), but the laser-irradiated group received split-mouth design, with orthodontic appliance on both sides and laser irradiation on one side only (group b) and on the contralateral side (group c). The orthodontic appliance consisted of a NiTi closed coil spring with a length of 5 mm which was ligated to maxillary molar and incisor. A total of 60 g of force was applied to the rat molar. The diode laser (660 nm) was irradiated with an output power of 25 mW in continuous mode for a total time of 5 min in the laser-irradiated group. After 14 days of orthodontic tooth movement, the amount of tooth movements was measured. In the laser-irradiated group, the amount of tooth movement was significantly greater than that of the non-irradiated group (2.3-fold), but there was no significant difference between the non-irradiated and indirectly irradiated groups. Histopathological studies revealed that the number of osteoclasts in the laser-irradiated group was significantly greater than that of the non-irradiated group (1.5-fold) while this number was almost the same in the non-irradiated and indirectly irradiated groups. The results suggested that low-level laser can accelerate the rate of bone remodeling. However, in order to utilize the low-level laser as an adjunct in orthodontic practice on patients, further research studies are needed for finding the appropriate dosage for the human tissues.

The effect of morphine on orthodontic tooth movement in rats.

OBJECTIVES: To investigate the effect of morphine as an exogenous opioid on orthodontic tooth movement. Naltrexone will be used as an opioid antagonist to confirm the results. METHODS: Forty rats were randomly divided into four equal groups. The first group received no injection; the second group received daily injections of morphine; the third group received daily naltrexone-morphine injections and the fourth group daily injections of naltrexone-normal saline. The left first maxillary molar in each rat was tipped mesially with a NiTi closed coil spring. The rats were sacrificed after 14 days and the maxillae fixed, sectioned serially and examined histologically. RESULTS: The greatest amount of tooth movement occurred in the Control group and the least amount of tooth movement in the Morphine group. Tooth movement in the Morphine group was significantly different from the other three groups (p < 0.05). The differences in tooth movement in the Control, Morphine-naltrexone and Naltrexonesaline groups were not statistically significant (p > 0.05). No statistically significant histological differences were found. CONCLUSIONS: Morphine reduced orthodontic tooth movement in rats. This effect was reversed by the opioid antagonist, naltrexone, which had no effect on tooth movement.