Kjeveortopedisk indusert ekstern apikal rotresorpsjon - grunnleggende og kliniske aspekter

Part 1: In spite of a lot of research on orthodontically induced external apical root resorption (OIEARR), much is still unknown about the resorption process. There is still uncertainty regarding the regulating factors involved in the resorption process and why only a small group of the patients experience severe OIEARR. There is however little doubt that the odontoclast has a central role in the resorption process. Studies have indicated that odontoclasts function a lot like osteoclasts and are regulated similarly. This simplifies the work of charting regulating substances, but much is still unknown in this field as well. Recently there has been conducted a lot of research on pharmacological agents that may increase root resistance to resorptions, aid in the reparatory process or regulate the cellular processes in the resorption process. At the moment pharmacological agents to counter OIEARR are not commonly used in orthodontic practices. This is partly due to contradictory research reports, potential side effects and the fact that clinicians at the time being are not able to identify patients with a risk of developing severe OIEARR. Abstract Part 2: The prevalence and severity of orthodontically induced external apical root resorption (OIEARR) are controlled by many factors. Recent research has shown that genetics contribute to at least 50 % of the variation in prevalence. Asians are less affected by OIEARR than Caucasians and Latinos. Aspects like anatomical differences, tooth position, distance of tooth movement, use of force, extractions, age and medical conditions have also been studied. The commonality for these factors is that none of them can be used as an exact indication of neither degree nor prevalence of root resorption. Most of the factors controlling the prevalence of OIEARR are still unknown or uncertain. Comparisons of various treatment techniques have not shown any technique to be superior in reducing OIEARR. A two phase treatment alternative is however a promising strategy that seems to reduce incisor resorption, though at the cost of a prolonged treatment. It is important to conduct thorough examinations and controls of all patients undergoing orthodontic treatment. Periapical radiographs (PAs) is still the most important clinical tool for detecting and diagnosing root resorption. OPT-radiographs often give uncertain results and might lead to over and under diagnosing of OIEARR. CBCT shows higher sensitivity than both PAs and OPT, and measurements done with CBCT are at least as precise and reliable. CBCT is good at estimating root volume loss and is better at visualizing, root morphology, surface resorptions, and alterations in root length than PAs and OPT. Radiation exposure from a CBCT exam is equivalent to a full mouth PA exam. CBCT might thus become a valuable diagnostic tool in orthodontic practices. Micro CT has shown similar results as CBCT. MRI-scanning might give additional information about OIEARR, but the procedure is way too expensive to be used on a regular basis. MRI-scans are also prone to artifacts when scanning areas containing metal. Teeth with severe OIEARR, with good oral hygiene and a healthy periodontium, show good long term prognoses when left untreated. If a conservative treatment is chosen, it is recommended to retain mobile teeth. Endodontic treatment of teeth affected with OIEARR is not needed. Extractions are however some times necessary. Prosthetic treatment is often needed to regain function and esthetics after extractions, but in some cases the tooth loss is also possible to correct with orthodontic treatment or auto transplants