Clinical Research Directory

Effect of Different Root Canal Preparation Sizes and Remaining Tooth Structure on the Survival of Endodontically Treated Mandibular Molars

Teeth that have undergone endodontic treatment are biomechanically weakened compared to vital teeth due to factors such as extensive carious lesions, previous restorations, loss of marginal ridges and pericervical dentin, and hard tissue removal during access cavity preparation and root canal instrumentation. Additionally, the quantity and quality of the remaining coronal tooth structure, the presence of marginal ridges, the ferrule effect, and the integrity of pericervical dentin directly influence both fracture resistance and the long-term success of restorations. Following endodontic access cavity preparation, the fracture resistance of the tooth decreases by approximately 5%. This reduction increases to around 20-30% in the case of unilateral marginal ridge loss (mesio-occlusal \[MO\] or disto-occlusal \[DO\] cavities), and can reach up to 63% when both marginal ridges are lost (mesio-occluso-distal \[MOD\] cavities). This condition may lead to cusp deflection under occlusal forces and, particularly in the absence of appropriate post-endodontic restoration, may result in failures such as vertical root fractures. It has been reported that, after caries removal and access cavity preparation, the amount of remaining sound coronal tooth structure may play an important role in determining the extent of mechanical preparation during treatment. The goal of mechanical preparation of the root canal system is to remove infected dentin and biofilm as much as possible and to create a continuously tapered canal shape that allows effective delivery of irrigants to the apical region. Although conventional preparation principles may provide higher levels of disinfection, they have been associated with reduced tooth strength, particularly due to the loss of resistance in the pericervical area. This has led to the development of more conservative root canal preparation strategies using instruments with smaller apical sizes and tapers. Previous studies investigating the relationship between preparation size and fracture resistance have shown considerable heterogeneity. Moreover, the predominantly in vitro nature of these studies limits their ability to accurately simulate clinical conditions. In addition, factors such as the amount of remaining tooth structure after treatment and the effectiveness of the final restoration are often overlooked. Therefore, it is important to support in vitro findings with clinical studies. To date, there is no long-term clinical study in the literature evaluating the combined effects of conventional and conservative preparation strategies on clinical survival and periodontal health in teeth with varying degrees of coronal tissue loss. The aim of this study is to clinically and radiographically evaluate the survival of mandibular molars with different amounts of remaining tooth structure (O, MO/DO, and MOD) following conventional and conservative root canal preparation. The null hypothesis is that different preparation strategies and the amount of remaining tooth structure have a similar effect on tooth survival.

MMP-2/3 and Periapical Healing Outcomes

This prospective randomized clinical study will investigate the association between MMP-2 and MMP-3 gene polymorphisms and radiographic healing outcomes following nonsurgical root canal treatment in patients with chronic apical periodontitis. A total of 50 patients will undergo standardized endodontic treatment and will be followed for 12 months. Genotyping will be performed using baseline DNA samples, and periapical healing will be assessed using the Periapical Index (PAI). The relationship between genetic variations and treatment outcomes will be analyzed to determine whether host-related genetic factors influence healing patterns after root canal therapy.

Comparative Evaluation of Endodontic Instrumentation Kinematics and Cryotherapy on Post-endodontic Pain and Periapical Healing

TITLE : Comparative evaluation of two different endodontic instrumentation kinematics and cryotherapy on post endodontic pain and periapical healing in teeth with asymptomatic apical periodontitis - A double blind, prospective randomized clinical trial Background : Root canal treatment is done to save teeth that are infected or damaged. Although this procedure relieves pain in the long term, many patients experience discomfort or pain after treatment, known as post-endodontic pain (PEP). The way dentists clean the root canals and the methods used to reduce inflammation may influence how much pain patients feel and how well the bone around the tooth heals. This study will compare two modern ways of cleaning root canals using special nickel-titanium files. The first method uses a rotary system, where the files continuously rotate inside the canal. The second method uses a reciprocating system, where the files move back and forth. Both systems are commonly used in dentistry, but it is still not clear which one leads to less pain and better healing. The study will also test the benefit of cryotherapy, which means rinsing the canal with very cold saline at the end of the cleaning. Cold therapy reduces blood flow and nerve activity, helping to control pain and swelling without the side effects of medicines. Methodology: Sixty patients with asymptomatic apical will be included. They will be randomly assigned into four groups: Group1:Rotary system with cryotherapy, Group 2:Rotary system without cryotherapy, Group 3: Reciprocating system with cryotherapy, Group 4 : Reciprocating system without cryotherapy.Patients will record their pain on a simple scale at different times after treatment. Healing of the infection will be checked with X-rays after six months. OBJECTIVES: Primary Objective: To compare the post endodontic pain following instrumentation with a rotary vs reciprocating kinematic instrumentation system at different irrigant temperature using NRS-11 scale. Secondary Objective: To assess the periapical healing following endodontic treatment with or without adjunctive use of cryotherapy assessed with periapical healing index . The results of this study will help dentists understand whether cryotherapy and the choice of instrumentation system can reduce patient discomfort and improve treatment success. This may lead to better patient care and less need for pain medications after root canal treatment.