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Morphology of the coronal root canal; First maxillary molar; Anatomy of a root canal; Reconfiguration in three dimensions

Introduction

One of the most undesirable conditions in a dental practice is root fracture (RF), which typically results in tooth loss [1]. A longitudinal tooth fracture known as a vertical root fracture (VRF) can be either a complete or incomplete fracture that originates from the root at any level. The fracture line runs parallel to the root canal and connects the root’s external surface to the wall of the canal. With or without postplacement, root canal-treated (RCT) teeth are more likely to develop VRF. Between 4% and 13% of extracted RCT teeth contain VRFs. VRF is caused by a number of multifactorial predisposing factors, including occlusal forces and stresses, excessive root canal preparation, instrumentation- or obturation-induced dentinal defects, post-space preparation and cementation, and root anatomy [2]. The maxillary central incisor is the tooth most frequently affected by horizontal root fracture (HRF), which occurs in the middle third of the root and is more frequently associated with traumatic injuries (0.5–7% of injuries). The HRF’s fracture line can cross the root’s long axis either perpendicularly or obliquely. In the literature, HRF in posterior teeth that have not been impacted has rarely been reported. Seventy-nine percent of the posterior teeth with HRFs in a Taiwanese population were non-root canal treated and had no previous history of accidental trauma.

The term “fatigue root fracture” was first used to describe a nonendodontically treated tooth with a root fracture that was caused by a lot of heavy, repetitive, and excessive masticatory stress. Depending on the orientation of the fracture line, chronic fatigue root fracture can be further divided into four categories: vertical, horizontal, oblique, and laminar [3]. Asians and Caucasians have reported this phenomenon more frequently than Caucasians. VRF was found in the mesial root of two mandibular first molars that were not treated with endodontics and in the mesiobuccal root of one maxillary first molar. They proposed that harmful chewing habits and special diets, such as chewing on meat cartilage, crab shells, ice cubes, sugar canes, etc., were factors that predispose to fatigue VRFs.

How common are non-RCT teeth with chronic fatigue root fracture in the Taiwanese population? There hasn’t been a study on it, and there hasn’t been a comparison of the clinical factors of fatigue HRFs and VRFs in teeth that haven’t had endodontic treatment [4]. Hence, the motivation behind this study was to examine the frequency and clinical qualities of persistent weakness root break in teeth separated at a short term oral and maxillofacial medical procedure facility in a medical clinic in Taipei during a one-year perception period.

Materials and Methods

Participants

This study was carried out at the Taipei Veterans General Hospital. The incidences of VRF and HRF in non-RCT teeth that resulted in tooth extraction were calculated, and the clinical characteristic features of VRF and HRF were reviewed [5]. Included were patients referred to the Division of Oral and Maxillofacial Surgery for permanent tooth extraction from the Taipei Veterans General Hospital’s Department of Stomatology. These patients’ periapical or panoramic radiographs were taken prior to tooth extraction. The reasons for tooth extraction or the diagnostic ICD-10-CM codes were recorded.

Criteria for exclusion

The following were the exclusion criteria: 1) Foreigners, regardless of whether they have national health insurance; 2) Supernumerary or deciduous teeth; 3) Cases with inadequate clinical or radiographic documentation; 4) Individuals under the age of twenty-one; 5) Extracted teeth that have extensive caries and may be at risk of tooth fracture during extraction.

The purposes behind tooth extraction were characterized into five classifications, in particular non-restorable carious teeth, periodontal illness, tooth break, impaction and pericoronitis, and others (for example pre-prosthetic or orthodontic reasons, or because of injury) - a characterization changed The classification of tooth break was subdelegated crown-beginning crack and root break. A split, cracked, and fractured cusp were among the crown-originating fractures [6]. VRF and HRF were the root fractures. A fracture line that runs either perpendicularly or obliquely across the root’s long axis was referred to as an HRF. Root canal-treated teeth were identified by the radiograph as having radiopaque fillings in the canals. Non-RCT teeth were those that were prepared for root canal treatment but had no access cavity. The presence of a distinct fracture line along the root canals, presenting radiographically as apical root canal space widening or displacement of fractured root fragments, was typically used to diagnose VRF in non-RCT teeth. The tooth with its remaining soft tissue was stored in a thymol solution and included in this study if it was a non-RCT tooth with radiographic features of VRF or HRF and no history of accidental trauma. Using a microscope (OPMI Pico), an endodontist confirmed the location and extension of the fracture line, as well as the diagnosis of VRF or HRF. Zeiss, Oberkochen, Germany), which was stained with methylene blue.

Non-RCT teeth with VRF and HRF were considered to have “chronic fatigue root fracture [7]. In all extracted teeth, the prevalence of chronic fatigue root fractures, including fatigue VRFs and HRFs in non-RCT teeth, was determined.

Clinical findings

The age, gender, type of tooth fracture, tooth position, fractured root morphology in cross-section (slight round or long oval in crosssection), with or without restoration, attrition (severe or not severe), a terminal tooth (yes or no), and missing 1 (at least one) adjacent tooth (yes or no) were all recorded in the clinical data of the non-RCT teeth in this study. As to root morphology, the mesial or distal root or the C-molded foundation of a mandibular molar, the mesiobuccal root or an intertwined buccal (mesiobuccal or distobuccal) and palatal foundations of a maxillary molar, the underlying foundations of a maxillary premolar, and the base of a mandibular incisor were named roots with a long oval cross-segment [8]. The remaining roots were all classified as having a slight round cross-section. Two endodontists independently evaluated the severity of attrition based on the clinical photograph and radiograph of the tooth. According to Smith & Knight, attrition indexes of 0 (no loss of enamel surface characteristics, no change in contour), 2 (loss of enamel characteristics, minimal loss of contour), and 3 (loss of enamel exposing dentine for more than 1/3) were considered to be moderate, while attrition indexes of 4 (complete loss of enamel, or pulp exposure) were considered to be severe. In order to reach a final agreement, any differences in how the attrition index was assigned to the two readers were discussed.

Radiographic findings

Two endodontists independently interpreted the radiographic findings of the chronic fatigue root fracture in non-RCT teeth and the bony destruction patterns surrounding them [9]. A distinct fracture line or the presence of a displaced root fragment were recorded as evidence of the root condition. The radiographic widening of the root canal space typically served as an illustration or characterization of the vertical fracture line in fatigue VRF. Each periradicular area’s radiographic appearance was broken down into seven categories.

Statistical analysis

The chi-square test or the Fisher exact test, as appropriate, was used to conduct statistical analysis on the clinical factors that were compared between HRF and VRF teeth [10]. The significance level was deemed to be below 0.05.

Results and Discussion

All extracted teeth in a teaching hospital in Taiwan were found to have non-RCT teeth with chronic fatigue root fractures, according to this cross-sectional study (32/4207). Due to the difficulty in making an accurate diagnosis of chronic fatigue root fracture at an early stage, the actual prevalence of this condition in the Asian population as a whole may be underestimated. The failure to identify chronic fatigue root fracture early is caused by the following factors: First and foremost, the majority of these teeth may be mistaken for periodontal disease, hypersensitivity due to severe attrition, or cracked tooth syndrome. This is because, in addition to the fact that the crowns of these teeth with chronic fatigue root fracture have little or no restoration, these patients may also initially exhibit non-specific symptoms of thermal sensitivity or discomfort when biting. Second, because the radiograph must be taken at the correct angulation of the X-ray beam, with the X-ray passing the fracture line within a range of 15°-20° from the buccal to the lingual surface, diagnosing chronic fatigue root fracture in its early stages is difficult [11]. The dental specialist, thusly, should be know about and experienced in persistent exhaustion root crack when deciphering the radiographs, and all the clinical data, as well as the radiographic discoveries of the patient, should be dissected and assessed all in all. Cone-beam computerized tomography (CT) images with a voxel size of 0.125 mm have been shown to have significantly higher sensitivities in detecting simulated HRF than intraoral radiographs. As a result, chronic fatigue root fracture is most commonly diagnosed in the late stage, when the fracture line was more distinguishable and the symptoms were more obvious [12]. The absence of cone-beam CT images for the detection of chronic fatigue root fracture is one of the limitations of this clinical study.

In this study, 4207 extracted permanent teeth were looked at. 263 (6.25%) of the 4207 teeth were extracted due to tooth fracture, and their clinical information was gathered. The types of tooth fractures as well as the numbers of the fractured teeth in teeth with root fractures and crown-originating fractures are listed [13]. 125 (47.53 percent) of the 263 extracted teeth had root fractures, while 138 (52.47 percent) had crown-originating fractures. The root fracture mostly affected RCT teeth, while the crown-originating fracture mostly affected non-RCT teeth. VRF and HRF were present in 16 of the 32 non-RCT teeth with chronic fatigue root fracture. The rate of constant weariness root crack in undeniably separated teeth was 0.76% (32/4207) during this oneyear perception period.

Conclusion

In conclusion, 0.76 percent of extracted teeth in this one-year study were found to have chronic fatigue root fracture, making this the first study to report this phenomenon in non-RCT teeth. There was a distinct fracture line or displacement of the fractured root fragment in all extracted teeth with chronic fatigue root fracture. Normal, halo, or vertical bone loss patterns were the patterns of bone destruction. The frequency of the fatigue VRF and fatigue HRF was similar, and they mostly affected older men, teeth with a lot of decay, and posterior teeth that had little or no restoration. In comparison to the fatigue HRF, the fatigue VRF was more prevalent in molars, teeth with long oval roots, and terminal teeth. For a better understanding of the nature of chronic fatigue root fracture, additional clinical and fundamental research should be carried out because prevention is superior to treatment.

Acknowledgement

None

Conflict of Interest

None

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