A critical analysis of research methods and experimental models to study dentinal microcracks

The purpose of this narrative review was to discuss the scientific milestones that led to the current understanding of the root dentinal microcrack phenomenon based on the interplay between the usage of micro-computed tomography (micro-CT) as an analytical tool alongside a close-to-mouth experimental model. In 2009, reports on the development of dentinal microcracks in extracted teeth after root canal preparation triggered an awareness of the potential for vertical root fractures (VRFs) of endodontically treated teeth could be developed from defects created by the mechanical stress of nickel-titanium preparation systems on dentine. This assumption was taken for granted, even though no cause-effect relationship had been scientifically demonstrated. Since then, several studies using the sectioning method with extracted teeth have been published and the large discrepancy amongst their outcomes soon become evident. Moreover, the high frequency of reported dentinal microcracks largely contrasted with the clinical incidence of VRFs, raising doubts on their methodological reliability. Using micro-CT technology, it was demonstrated by several studies that, in extracted teeth, dentinal defects already existed before the endodontic procedures, indicating that the initial reports framed a non-existing cause-effect relationship between canal preparation and dentinal microcracks. Although these new findings contributed to a better comprehension of this phenomenon, the misconception that microcracks were the starting point for VRFs was only surpassed with a new in situ approach using fresh cadavers. Surprisingly, microcracks were not identified in sound teeth. As a conclusion, dentinal microcracks in extracted teeth can be considered a non-natural occurrence observed only in a laboratory set-up as a consequence of dehydration and storage conditions. Thus, dentinal microcracks shall not be considered as the starting point for VRFs as they do not manifest in non-extracted teeth. Identifying dentinal microcracks as a laboratory phenomenon highlights the impact of recent scientific developments to disclaim the clinical relevance of laboratory-obtained outcomes.

Decision-Making and Management of Immature Permanent Teeth with Crown Fractures in Small Animals-A Review

Immature permanent teeth with crown fractures present a unique challenge in human and animal patients. Immature permanent teeth have not yet developed completely, often presenting with thin dentin walls, incomplete apical formation, and increased crown-to-root ratios. Loss of pulp function at this stage has devastating long-term implications for these teeth. Ideally, attempts should be made to preserve pulp vitality in immature permanent teeth to allow for continued dental development. The range of treatment options for vital teeth includes odontoplasty with bonding and sealing +/- restoration, indirect pulp capping, and direct pulp capping/vital pulp therapy. These treatments have long been established in human and veterinary medicine, and cases have been reported in dogs and cats. Apexification using calcium hydroxide is a well-established treatment for nonvital immature teeth. The advent of mineral trioxide aggregate and other bioceramic materials for use in vital pulp therapy and apexification has reduced treatment sessions and improved outcomes. Recent developments in the field of regenerative endodontic therapy further expand treatment options and provide the possibility for continued development of a formerly nonvital tooth. Selecting the appropriate treatment based on the severity of tooth fracture and status of pulp vitality can avoid a lifetime of poor structure and function for the affected tooth. This article provides multiple step-by-step protocols for the management of immature permanent teeth with crown fractures in small animals.

Influence of size of field of view (FOV), position within the FOV, and scanning mode on the detection of root fracture and observer's perception of artifacts in CBCT images

OBJECTIVE

To assess the influence of field of view (FOV) size, scanning position within the FOV and scanning mode on the detection of root fracture and artifact perception.

METHODS

Forty single-rooted premolars restored with NiCr and AgPd posts were divided into two groups: fractured and sound. All teeth were scanned using four CBCT scanning protocols varying FOV sizes (80 × 80 mm and 50 × 55 mm) and scanning modes (Standard and High Definition). The sample was positioned within the FOV in two pre-set positions (central and lateral) and in four positions established by the operator (quadrants). Detection of root fracture and artifact perception were assessed by two observers using 5-point and 4-point scales. Sensitivity, specificity, accuracy, and AUC values were calculated and compared by ANOVA two-way and Tukey's test. Chi-square and Fisher's exact test were used to assess artifact perception. The level of significance was set at p < 0.05.

RESULTS

The central position within the FOV presented higher sensitivity, specificity, accuracy, and AUC values and differed from the lateral position within the FOV for the studied metal posts (p<0.05). Quadrant 2 presented the best sensitivity, accuracy, and AUC values (p<0.05). The lateral position within the FOV, AgPd posts, quadrants 1 and 3 and protocols 1 (SM, 80 × 80) and 2 (HD, 80× 80) presented higher frequency of artifacts classified as "severe".

CONCLUSION

Positioning the object in the center or closer to the anterior periphery of the FOV while using a small FOV improved the detection of root fracture and decreased artifact perception.

Conservative Treatment of Complicated Crown Fracture and Crown-Root Fracture of Young Permanent Incisor-A Case Report with 24-Month Follow-Up

The complicated crown-root fracture of young permanent teeth is an uncommon traumatic dental injury that is usually treated in a complex way and is demanding not only for the dentist but even for the treated child. In this case report, we present the conservative treatment of a maxillary central incisor in a 10-year-old boy after a traumatic dental injury. Treatment included partial pulpotomy and adhesive fragment reattachment after reflection of the mucoperiosteal flap. The patient was fully asymptomatic at 24-month follow-up, with an aesthetically acceptable outcome. Vital pulp therapy and adhesive fragment reattachment can be a viable treatment option for complicated crown-root fractures, especially when treating immature permanent teeth.

Fracture resistance of endodontically treated premolars restored with bulk-fill composite resins: The effect of fiber reinforcement

BACKGROUND

Coronal restoration of endodontically treated teeth (ETT) with mesio-occluso-distal (MOD) cavities is of a great importance in long-term success of the treatment. This study evaluated the effect of fiber reinforcement on the fracture resistance (FR) of ETT restored with flowable or paste bulk (PB)-fill composite resin compared to conventional composite (CC) resin.

MATERIALS AND METHODS

In this in vitro experimental study, eighty maxillary premolars were divided into eight groups (n = 10). The first group was left intact (G₁) and the other groups received MOD cavities along with endodontic treatment. G₂: Remained unrestored while the other experimental groups were restored with three types of composite resin with or without fiber insertion. G₃: CC resin, G₄: PB fill, G₅: Flowable bulk fill (FB). G₆: Fiber + CC, G₇: Fiber + PB, and G₈: Fiber + FB. FR was tested at crosshead speed of 1 mm/min and recorded in Newton. Data were analyzed using one-way analysis of variance and Tukey's tests at significance level of P < 0.05.

RESULTS

G₁ and G2 revealed the highest and the lowest FR, respectively. The mean FR of the testing groups in Newton was as follows: G₁ = 1204.8 ^A, G₂ = 352.1 ^C, G₃ = 579.6 ^BD, G₄ = 596.7 ^BD, G₅ = 624.9 ^BDE, G₆ = 858.3 ^E, G₇ = 529.6 ^CB, and G₈ = 802.5^DE. Different uppercase letters indicate the significant difference between the groups.

CONCLUSION

The effect of fiber insertion on FR depended on the type of composite resin; the highest reinforcing effect was obtained in the CC resin + fiber, followed by bulk-fill flowable + fiber, and flowable bulk (FB)-fill composite resin. The strength of the former was significantly higher than the conventional and PB fill with and without fiber.

European Society of Endodontology position statement: endodontic management of traumatized permanent teeth

This position statement represents a consensus of an expert committee convened by the European Society of Endodontology (ESE) on the endodontic management of traumatized permanent teeth. A recent comprehensive review with detailed background information provides the basis for this position statement (Krastl et al. 2021, International Endodontic Journal, https://doi.org/10.1111/iej.13508). The statement is based on current scientific evidence as well as the expertise of the committee. Complementing the recently revised guidelines of the International Association of Dental Traumatology, this position statement aims to provide clinical guidance for the choice of the appropriate endodontic approach for traumatized permanent teeth. Given the dynamic nature of research in this area, this position statement will be updated at appropriate intervals.

Endodontic management of traumatized permanent teeth: a comprehensive review

The pulp plays a key role in the treatment of traumatic dental injuries (TDIs) and is strongly associated with the outcome, particularly in severe cases. A correct pulp diagnosis is essential as it forms the basis for developing the appropriate management strategy. However, many TDIs are complex, and their treatment requires a profound knowledge of the physiological and pathological responses of the affected tissues. This comprehensive review will look at the dentine-pulp complex and its interaction with the surrounding tissues following TDIs. The literature up to 2020 was reviewed based on several searches on PubMed and the Cochrane Library using relevant terms. In addition to the recently revised guidelines of the International Association of Dental Traumatology, this article aims to provide background information with a focus on endodontic aspects and to gather evidence on which a clinician can make decisions on the choice of the appropriate endodontic approach for traumatized permanent teeth.

Accuracy of three cone-beam CT devices and two software systems in the detection of vertical root fractures

OBJECTIVES

The aim of this study was to compare the accuracy of vertical root fracture (VRF) detection using three tomography devices and two software systems in teeth with different endodontic fillings.

METHODS

The sample consisted of 45 premolars divided into 3 groups: No filling (NF, n=15); Gutta percha (GP, n=15) and Metallic Post (MP, n=15). Cone-beam computed tomography (CBCT) images were acquired in Kodak 9000 3D, Orthopantomography 300 (OP300) and PreXion 3D devices, before and after induced root fractures. Two oral radiologists analyzed all images using InVivoDental and e-Vol DX software systems. The analysis was repeated after 15 days in 30% of the sample. Data analysis compared receiver operating characteristic (ROC) curves, as well the areas under the ROC curves. Accuracy, sensitivity, specificity, positive and negative predictive value were calculated according to each tomographic device and software. Intra- and interexaminer reliability were tested using the Kappa coefficient.

RESULTS

The highest accuracy was seen in the image set from the PreXion 3D, using InVivo (0.96) or e-Vol DX (0.92) in image analysis. The OP300 device presented a similar performance of the PreXion 3D in teeth with different endodontic fillings. When using e-Vol DX, the accuracy of Kodak 9000 3D improved from 0.62 to 0.74.

CONCLUSIONS

The PreXion 3D device is the most accurate when detecting VRF, with a performance similar to the OP300 in endodontic filled teeth. Kodak 9000 3D is indicated for teeth without fillings, with better accuracy using e-Vol DX software.

On the ability of experimental impact measures to predict tooth injuries in an ex vivo swine model

BACKGROUND/AIM

Impact to the orofacial region, in particular teeth, is a frequent incident leading to injury in many sports and can result in health and economic costs for the injured individual. The majority of previous work has applied synthetic models such as plaster or stone, to form analogs of relevant structures to study the potential for impact-induced injury. Biomechanical studies that have applied tissue models (animal or human) for the purpose of determining the biomechanical measures associated with dental injury are rare. The aim of this study was to apply a simple ex vivo model based on swine dentition to ascertain which of a select list of measurable quantities associated with impact mechanics could predict luxation and fracture of teeth due to impact.

METHODS

Mandibular central incisors of ex vivo swine dentitions were impacted using a linear drop tower with heights ranging from 1.20 m to 2.42 m. Seven mechanical predictors were assessed at impact and were then subjected to binary logistic regression techniques to determine which was the best predictor of luxations or fractures of the teeth.

RESULTS

Of the seven mechanical predictors, (1) the velocity of the impacting body (R²  = 0.477), (2) a proxy measure for the change in kinetic energy of the impacting body (R²  = 0.586), and (3) the approximate energy absorbed by the tissue (R²  = 0.722) were found to be statistically significantly different (p < .05), offering the greatest specificity as indicated by receiver operator characteristics. Other measures that are frequently used in impact mechanics, including peak linear acceleration and velocity change, were not statistically significant predictors of tooth injury.

CONCLUSION

Identifying mechanical predictors for dental injury of unprotected teeth provides a first step in understanding which aspects of an impact event attribute to dental injury and can lay the foundation for future studies that examine alteration in injury mechanics associated with protection devices.

Baseline characteristics as 3-year predictors of tooth fracture and crack progression: Findings from The National Dental Practice-Based Research Network

BACKGROUND

The authors of this practice-based study estimated the risk of experiencing tooth fractures and crack progression over 3 years and correlated baseline patient-, tooth-, and crack-level characteristics with these outcomes.

METHODS

Two-hundred-and-nine National Dental Practice-Based Research Network dentists enrolled a convenience sample of 2,601 participants with a cracked vital posterior tooth that had been examined for at least 1 recall visit over 3 years. Data were collected at the patient, tooth, and crack levels at baseline, annual follow-up visits, and any interim visits. Associations between these characteristics and the subsequent same-tooth fractures and crack progression were quantified.

RESULTS

Of the 2,601 teeth with a crack or cracks at baseline, 78 (3.0%; 95% confidence interval, 2.4% to 3.7%) subsequently developed a fracture. Of the 1,889 patients untreated before year 1, 232 (12.3%; 95% confidence interval, 10.9% to 13.8%) had some type of crack progression. Baseline tooth-level characteristics associated with tooth fracture were the tooth was maxillary and had a wear facet through enamel and a crack was detectable with an explorer, on the facial surface, and in a horizontal direction. Crack progression was associated with males and teeth with multiple cracks at baseline; teeth with a baseline facial crack were less likely to show crack progression. There was no commonality between characteristics associated with tooth fracture and those associated with crack progression.

CONCLUSIONS

Development of tooth fractures and crack progression over 3 years were rare occurrences. Specific characteristics were associated with the development of tooth fracture and crack progression, although none were common to both.

PRACTICAL IMPLICATIONS

This information can aid dentists in assessing factors that place posterior cracked teeth at risk of experiencing adverse outcomes.

Effect of Alternative Palatal Root Access Technique on Fracture Resistance of Root Canal Treated Maxillary Fourth Premolar Teeth in Dogs

A biomechanical study was performed to identify the effect of different treatment methods for difficult to instrument palatal roots on the fracture resistance of root canal treated maxillary fourth premolar teeth in dogs. Forty maxillary fourth premolar teeth with surrounding alveolar bone were harvested from beagle cadavers. Inclusion criteria included maxillary fourth premolars with no evidence of disease and similar distal root canal volumes on radiographic evaluation. The teeth were randomly divided into a control group and three treatment groups based on the endodontic treatment technique for the palatal root. The control group had a single 2 mm transcoronal access on the mesiobuccal aspect of the tooth to allow instrumentation of both the mesiobuccal and palatal root through a single small access. Alternative treatment modalities that are described for difficult to instrument palatal roots investigated in this study included enlarging the transcoronal mesiobuccal access to 4 mm, making an additional access directly over the palatal root (2 mm), and hemisection with extraction of the palatal root. All teeth had the same distal root access size (2 mm) and relative location. After access, all teeth were filed, shaped, obturated, and restored in the same fashion. Axial compression testing was performed at an angle of 60 degrees to the long axis of the tooth using a universal materials testing machine. The maximum force prior to fracture was determined for each tooth based on a force vs. deflection curve. The mean maximum force prior to fracture for all teeth was 831 N. No significant difference in mean fracture resistance was identified between the control group and treatment groups or between the different treatment groups themselves. Thus, when faced with a difficult to instrument palatal root, the treatment method chosen should be based on operator preference and experience.

The prevalence of traumatic dental injuries in primary teeth: A systematic review and meta-analysis

BACKGROUND/AIMS

The varied prevalence of traumatic dental injuries (TDI) in primary teeth around the globe raises a serious knowledge gap in the available literature. The aim of this study was to evaluate the prevalence of TDI in primary teeth and also to evaluate the different factors associated with TDI in primary teeth.

MATERIALS AND METHODS

Comprehensive searches were performed in PubMed, Embase, Google Scholar, and The Cochrane Central Register of Controlled Trials with predefined search criteria. The primary outcome was the prevalence of TDI in primary teeth, and the secondary outcomes were the factors associated with TDI in primary teeth. Qualitative analysis was done using the Newcastle-Ottawa scale adapted for cross-sectional studies. The random-effect model was used for meta-analysis, and meta-regression analysis was done to evaluate the heterogeneity between the included studies. Meta-analysis was done using the "meta" package of "R" language. The overall quality of evidence was assessed using GRADEpro GDT software.

RESULTS

A total of 24 cross-sectional studies met the inclusion criteria representing 4876 TDIs in 22 839 children aged between 0 and 6 years old. The overall prevalence of TDI in primary teeth was 24.2% (95% CI: 18.24-31.43, P = 0, I²  = 99%). Falls contributed the highest number of TDI - 59.3% (95% CI: 41.05-76.40, P < .01, I²  = 98%) - in primary teeth. The most common type of tooth fracture in primary teeth was an enamel fracture (61.9%), and prevalence of TDI in children with incompetent lip closure was 49.4%.

CONCLUSION

The prevalence of TDI in cross-sectional studies of primary teeth was 24.2% with very low quality of evidence. Falls contributed the highest number of TDI in primary teeth, accounting for 59.3%. Children with incompetent lip closure have the highest prevalence (49.4%) of TDI in primary teeth.

Mouthguard use and attitudes regarding dental trauma among elite cross-country mountain biking and field hockey athletes

BACKGROUND/AIMS

Cross-country mountain biking and field hockey are two Olympic sports that pose a potential risk for dentofacial trauma. However, mouthguard use is not mandatory in either of these sports and knowledge about tooth rescue among athletes is often neglected. The aim of this cross-sectional epidemiological survey was to evaluate the prevalence of sports-related dentofacial injuries, mouthguard use, and attitudes regarding tooth rescue among cross-country mountain biking and field hockey athletes participating at pre-Olympic competitions held in Rio de Janeiro, Brazil.

MATERIALS AND METHODS

A convenience sample of 217 athletes from 33 countries participating in cross-country mountain biking (n = 82; mean age = 30.96 ± 8.52 years) and field hockey (n = 135; mean age = 19.72 ± 2.46 years) pre-Olympic competitions were examined clinically, and they answered a questionnaire regarding previous history of sports-related dentofacial injuries, attitudes toward mouthguard use, and tooth rescue.

RESULTS

There were 120 (55.30%) males and 97 (44.70%) females who participated in the study. The prevalence of facial trauma was higher in mountain biking (54.88%) than in field hockey (26.66%, P < .001). Fracture was the most prevalent facial injury in mountain biking (80%), while laceration was the most prevalent in field hockey (30.55%). Extensive dental injuries occurred more often in mountain biking (47.37%) than in hockey (12.50%). The teeth most often affected were the maxillary central incisors in both mountain biking (57.89%) and field hockey (93.75%). Mouthguard use was more frequent among field hockey athletes (41.48%) than in mountain biking (1.22%, P < .001). The overall knowledge about tooth rescue was low, and most of the athletes in both sports did not know what to do in case of an avulsed tooth.

CONCLUSIONS

Prevalence of dentofacial injuries among XCO-MTB and field hockey athletes participating at this pre-Olympic event was high. The majority of the athletes in this study did not use mouthguards and were unaware of recommendations in the case of an avulsed tooth.

Injury Prevention, Safety Education and Violence in Relation to the Risk of Tooth Fracture among Korean Adolescents

This study aimed to determine the injury prevention-, safety education-, and violence-related factors pertaining to tooth fracture experience (TFE) in Korean adolescents. We used data from the 14th Korea Youth Risk Behavior Survey (KYRBS) in 2018. The 60,040 participants were selected using a complex sampling design from middle and high schools. The participants completed a self-administered questionnaire. The explanatory variables, including school safety education and violence, were assessed in relation to prevention of traumatic injuries. Complex-samples multivariable logistic regression models were applied to explain the factors related to TFE over the past 12 months. The overall prevalence of TFE was 11.4%. Risk factors related to tooth fractures were not wearing a seatbelt on an express bus, not wearing helmets while riding motorcycles and bicycles, clinical treatment due to injuries at school, injuries associated with earphone/smartphones use, and lack of school safety education such as danger evacuation training. The top risk factor was injuries associated with earphone/smartphone usage, followed by lack of familiarity with school safety education. Thus, to prevent tooth fractures among adolescents, schools should strengthen their safety education, including education regarding mobile device usage, and wearing a seatbelt and wearing a helmet. Care should be taken to manage facilities around the school and to prevent injury related to tooth fracture. Further studies on various risk factors related to tooth fractures are warranted.

Prevalence of traumatic dental injuries in India: A systematic review and meta-analysis

Objective

The aim of this systematic review and meta-analysis was to estimate the prevalence of traumatic dental injuries (TDI) in India. The secondary objective was to evaluate the prevalence rate according to the differences in gender, age, regions, type of TDI and risk factors associated with TDI.

Methods

The PubMed, LILACS, Web of Science, Cochrane, CINHAL, and Scopus databases, along with the Public Health Electronic Library, TRoPHI and DoPHER were searched from 1^st March to 15^thApril 2019 without any restriction of language and year of publication. The qualitative synthesis was done regarding the demographics, study methods, cause of trauma, geographic location, increased overjet and inadequate lip coverage. The meta-analysis was undertaken with STATA-14 software (USA). The pooled prevalence of TDI was calculated using data extracted from 48 studies included in qualitative synthesis and meta-analysis. A sub-group meta-analysis was done by extraction of the data for age groups of 6 years and >6 years.

Results

The pooled prevalence of TDI in Indian population was 13 cases in 100 individuals. The prevalence of TDI for age groups of ≤6 was 15% (males, 15%; females, 16%) and for >6 years was 12% (males, 13%; females, 8%). The most common cause of TDI was falls, and most frequent location was home. The odds ratio for occurrence of TDI and inadequate lip-coverage was 3.35 and overjet greater than 3 mm was 3.53.

Conclusions

The pooled prevalence of TDI was 13% and slightly higher in children less than 6 years of age. Inadequate lip coverage and increased overjet are the risk factors associated with TDI. Heterogeneity was observed among the studies in terms of design, variables recorded, sampling, study methods and statistical methods. Majority of them also suffered from moderate to high risk of bias.

Health-Risk Behavior-, Mental Health-, and Physical Exercise-Related Risk Factors for Tooth Fractures in Korean Adolescents

We aimed to determine factors related to tooth fracture experience in Korean adolescents. This study used data from the 14th Korea Youth Risk Behavior Survey in 2018, a cross-sectional web-based survey of health-risk behaviors among a representative sample of Korean middle- and high-school students aged 12–17 years. A total of 60,040 participants were selected using a complex sampling design of the survey from 400 middle schools and 400 high schools. They answered a self-administered questionnaire survey in classrooms. Explanatory variables included those pertaining to health-risk behaviors, mental health, and physical exercise. Complex-sample multivariable logistic regression models were applied to identify factors related to tooth fracture experience in the past 12 months. The overall prevalence of dental fracture experience was 11.4%. Risk factors related to tooth fractures in Korean adolescents were unhealthy behaviors such as alcohol and tobacco consumption; mental health problems including stress, depression, and suicidal ideation; and intensive physical exercise. The major risk factor related to tooth fractures was depression. To prevent tooth fractures among adolescents, schools should strengthen mental health education, encourage mouthguard use during intensive physical exercise, and develop school environments to prevent orofacial injuries. Further studies on various risk factors related to tooth fractures are warranted.

The Incidence of Radiographic Lesions of Endodontic Origin Associated With Uncomplicated Crown Fractures of the Maxillary Fourth Premolar in Canine Patients

Fractured maxillary fourth premolar teeth are commonly diagnosed in canine patients. These fractures are subdivided into uncomplicated and complicated, depending on absence or presence of pulp exposure, respectively. Pulp injury associated with fractures can lead to pulpitis, pulp necrosis, and "lesions of endodontic origin" (LEO) on intraoral radiographs. The incidence of LEO associated with uncomplicated crown fractures (UCFs) of the maxillary fourth premolar in canine patients is currently unknown. We hypothesized that a significant number of UCFs of the maxillary fourth premolar would have LEO evident on intraoral radiographs. The purpose of this article was to identify this incidence and to illustrate the importance of radiographing these teeth. This was a retrospective study of 111 UCFs and 500 nonfractured (control) maxillary fourth premolars in domestic canine patients. The frequency of LEO was 24.3% (27/111) in the UCF population and 0% (0/500) in the control population (P < .0001). These findings are important because UCFs are sometimes ignored or considered insignificant, when in fact a large proportion of them have LEO, indicating periapical pathology. These results suggest that all UCFs be radiographed, even if there are no other abnormalities noted on clinical oral examination.

The International Association of Dental Traumatology ToothSOS mobile app: A 2-year report

BACKGROUND/AIM

The shift in health care and technology calls for innovation through mobile applications as free educational resources for the masses. The International Association of Dental Traumatology (IADT) created ToothSOS, an app (software application for mobile devices) to provide dental trauma information for patients and professionals. The app contains information on the emergency management and prevention of dental injuries, as well as treatment guidelines for dental practitioners. The aim of this study was to assess public utilization of the ToothSOS app in the first 2 years since its launch.

METHODS

The ToothSOS app was launched by the IADT in the first week of April 2018. Data regarding the number of downloads and usage of the app in the first 2 years (from April 2018 to May 2020) were collected and analyzed.

RESULTS

The total number of ToothSOS downloads over the 2 years was 47 725. The number of downloads peaked in the first month when the app was initially released. Thereafter, the number of downloads decreased to an average of 1423 ± 363 downloads every month. Europe was the territory with the greatest number of downloads followed by the United States and Canada, Asia, Latin America and the Caribbean, and Africa, the Middle East, and India.

CONCLUSIONS

Within as short a period as 2 years, the ToothSOS app continues to gain public interest. Further attempts and public campaigns should be made in order to increase the visibility of the app. Dental professionals should encourage patients and communities to use the app in order to increase awareness for the prevention and proper emergency management of traumatic dental injuries.

Management of an Unsuccessful Regenerative Endodontic Procedure after Tooth Fracture: A Case Report

Dental trauma is a very frequent occurrence in children and adolescents, which creates a great impact on the esthetics, functions, and phonetics. Traumatic dental injuries can range from simple enamel fractures to permanent tooth loss. This case report presents an eight-year-old patient with an uncomplicated crown fracture of tooth 21, and 30 days after trauma, it was diagnosed as necrotic pulp. The first treatment choice was a regenerative endodontic procedure (REP), however, the failure led to apexification with Mineral Trioxide Aggregate (MTA). The chosen rehabilitation was a composite veneer. Concerning the available literature and fracture enamel dentin, the treatment approach proposed for the case provided good functional and esthetic outcomes.

Dental injuries at the Xi'an, China Stomatological Hospital: A Retrospective Study

BACKGROUND/AIM

In order to enrich epidemiological knowledge regarding traumatic dental injuries (TDI) in China, and to further improve the treatment, prevention and education of TDI, the aim of this study was to retrospectively analyze the TDI that presented to the emergency dental department at the Stomatological Hospital in Xi'an, China.

METHODS

This retrospective study included all first-visit patients who presented with TDI at the Stomatological Hospital affiliated with the Fourth Military Medical University in Xi'an, China, between January 2013 and June 2019. Data were extracted using the terms of diagnosis of TDI from the hospital database.

RESULTS

Overall, 965 (606 males and 359 females) files were reviewed. The average age was 22.8 ± 13.4 years. Among the 2059 teeth injured (average of 2.1 teeth per patient), the maxillary incisors (1751; 85.0%) were the most prevalent teeth to present with injuries, while the main types of injuries were concussions (14.8%) enamel-dentin-fractures (14.50%) and enamel-dentin-pulp fractures (14.0%). After initial examination and diagnosis, 4.2% patients refused treatment.

CONCLUSIONS

The epidemiological statistics of TDI in Xi'an, China show consistency with other studies from around the world, but they also vary in diagnosis proportion and the choice of treatments. This information may further instruct treatment, prevention and emergency resources distribution to target the high-risk groups.

[Sterilization in dentistry. Limitations of elastic materials: a case presentation]

In everyday dental practice, sterility is essential. Sterilizing different materials can require different methods. In the case of heat sensitive and elastic materials, most common techniques are not suitable because they need to be treated on lower temperature, not to lose their physical properties. For instance, if rubber dam is divested of elasticity, it is useless in restorative dentistry thereafter. Sterilizing rubber dam sheets is not a frequent process, but in certain cases it can be necessary. In such a situation, dentists have to choose between rare and hard-to-reach options. In our referral, we summarize the possibilities of sterilization, focusing on plasma sterilization and hydrogen-peroxide vapor sterilization. During the treatment of our presented case with a deep subgingival fracture line, affecting the crown and the root surface as well, we applied a rubber dam sheet, sterilized with hydrogen-peroxide vapor in order to use adhesive technique. Orv Hetil. 2020; 161(3): 110-115.

Tooth fracture frequency in gray wolves reflects prey availability

Exceptionally high rates of tooth fracture in large Pleistocene carnivorans imply intensified interspecific competition, given that tooth fracture rises with increased bone consumption, a behavior that likely occurs when prey are difficult to acquire. To assess the link between prey availability and dental attrition, we documented dental fracture rates over decades among three well-studied populations of extant gray wolves that differed in prey:predator ratio and levels of carcass utilization. When prey:predator ratios declined, kills were more fully consumed, and rates of tooth fracture more than doubled. This supports tooth fracture frequency as a relative measure of the difficulty of acquiring prey, and reveals a rapid response to diminished food levels in large carnivores despite risks of infection and reduced fitness due to dental injuries. More broadly, large carnivore tooth fracture frequency likely reflects energetic stress, an aspect of predator success that is challenging to quantify in wild populations.

Gray wolves roam many European and American landscapes, where they prey on large animals such as elk and moose. A healthy dentition is essential for these predators to kill, eat and defend themselves. As a result, they tend to avoid biting down on tough body parts, such as bones, so that their teeth do not break. If food becomes scarce however, the wolves may resort to consuming these hard elements, eating more of the carcasses and leading to more damaged teeth. It could therefore be possible to assess the food levels available to existing (or even extinct) wolf populations based on how many broken teeth the animals have. However, older individuals are also more likely to have more damaged teeth, so age would need to be taken into consideration.

Van Valkenburgh et al. decided to evaluate whether it was indeed possible to deduce how much food was available to groups of wolves based on teeth damage. Tooth wear and fracture were quantified in three current populations of gray wolves whose skulls had been collected and preserved in natural history collections. For each group, there were data available about the variations of number of moose per wolf over time, and how much of the carcasses the wolves were consuming. The analyses showed that indeed, when prey became less abundant, the wolves ate more of the remains – including the bones – and therefore broke more teeth.

These conclusions can be applied to other large predators and even to extinct species such as dire wolves or sabertooth cats. Tapping into the potential of museum specimens could help to retrace environmental conditions and the history of animals now long gone.

Endodontically treated posterior teeth restored with or without crown restorations: A 5-year retrospective study of survival rates from fracture

AIM

The aim of the present study was to investigate survival rates from fracture of endodontically treated posterior teeth (ETT) restored with or without crowns with recall periods of up to 5 years.

METHODS

ETT with single-unit crown or resin composite restorations were studied based on the inclusion criteria. Restoration, tooth structure loss, adjacent teeth, fracture, and restorability were recorded. Survival rates from fracture were calculated, and risk factors were identified.

RESULTS

Overall, survival rate of ETT with crowns (92.2%) was significantly higher than resin composites (77.4%) (P < 0.05). ETT with one or two surface loss/es and two adjacent teeth had a high survival rate of 86.9%, which was not significantly different to ETT with crowns (P ≥ 0.05). Restoration and adjacent teeth were identified as significant factors. The majority of fractured ETT with resin composites were restorable, whereas those with crowns were unrestorable. Survival rates from unrestorable fracture were not significantly different between the crown (93.1%) and resin composite (96%) (P ≥ 0.05).

CONCLUSIONS

The survival rate from the fracture of ETT restored with crowns was significantly higher than ETT restored with resin composites, but was not significantly different to ETT with one or two ETT with one or two surface loss/es and two adjacent teeth. ETT restored with resin composites had mostly restorable fracture, whereas ETT with unrestorable fracture were similar between the two restorations.

Evaluation of the influence of various restoration techniques on fracture resistance of endodontically treated teeth with different cavity wall thicknesses

AIMS

The aim of this study was to compare the effect of different restoration techniques on fracture resistance of endodontically treated teeth with different wall thicknesses.

MATERIALS AND METHODS

Extracted and endodontically treated 210 premolars were randomly divided into three thickness groups [2 mm (A), 1.5 mm (B), and 1 mm (C)] and, each group was further divided into seven restoration subgroups (n = 10): direct composite (control) (K), composite with fiber on cavity floor (KT), composite with fiber on occlusal level (KO), fiber post and composite (FP), inlay (L), fiber on cavity floor and inlay (LT), and inlay and fiber on occlusal level (LO). Fracture test was performed, and data were compared with Kruskal-Wallis and Mann-Whitney U tests (P < 0.05).

RESULTS

There were no differences between the subgroups in A and C statistically (P > 0.05). However, in B, KO subgroup showed statistically higher values (P = 0.039).

CONCLUSION

Wall support of 2 mm was adequate, and support of 1 mm was completely insufficient. When the wall thickness was 1.5 mm, direct restoration with fiber at the occlusal level significantly improved resistance.

Fracture Limits of Maxillary Fourth Premolar Teeth in Domestic Dogs Under Applied Forces

A cadaveric study was performed to investigate the external mechanical forces required to fracture maxillary fourth premolar teeth in domestic dogs and describe a clinically relevant model of chewing forces placed on functionally important teeth in which fracture patterns are consistent with those defined by the American Veterinary Dental College (AVDC). Twenty-four maxillary fourth premolar teeth were harvested from dog cadavers. Samples consisted of teeth with surrounding alveolar bone potted in polycarbonate cylinders filled with acrylic. The cylinders were held by an aluminum device at an angle of 60° with respect to the ground. An axial compression test was performed, creating a force upon the occluso-palatal aspects of the main cusps of the crowns of the teeth. The highest compressive force prior to failure was considered the maximum force sustained by the teeth. Results showed the mean maximum force (± SD) sustained by the tested teeth at the point of fracture was 1,281 N (± 403 N) at a mean impact angle (± SD) of 59.7° (± 5.2°). The most common fracture type that occurred among all samples was a complicated crown fracture (n = 12), followed by an uncomplicated crown fracture (n = 6), complicated crown-root fracture (n = 5), and uncomplicated crown-root fracture (n = 1). There was no statistically significant correlation between dog breed, age, weight, impact angle, crown height or crown diameter, and the maximum force applied at the point of fracture. The only independent variable that remained significantly associated with maximum force was the crown height to diameter ratio (p = 0.005), suggesting that a decreased ratio increases tooth fracture resistance. The methodology described herein has been successful in creating a pattern of fracture of maxillary fourth premolar teeth consistent with that defined by the AVDC under angled compression at forces within the maximum chewing capability of the average domestic dog.