Symptom changes and crack progression in untreated cracked teeth: One-year findings from the National Dental Practice-Based Research Network

Occlusal veneer restoration treatment outcomes of cracked tooth syndrome: A 22.4-month follow-up study

OBJECTIVES

The aims of this clinical study were to investigate success rate, vital pulp survival rate, tooth survival rate and patient-reported masticatory ability by evaluating the pain symptoms and signs of the cracked teeth as well as Index of Eating Difficulty (IED) and Oral Health Impact Profile-14 (OHIP-14) questionnaire after cracked teeth were restored with occlusal veneers.

MATERIALS AND METHODS

27 cracked teeth of 24 patients with cold and/or biting pains without spontaneous/nocturnal pains were recruited in this study. The cracked teeth were restored with occlusal veneers fabricated by lithium disilicate ceramic. Cold test and biting test were used to evaluate pain signs. IED and OHIP-14 questionnaire were used to evaluate masticatory ability. FDI criteria was used to evaluate restorations. The paired Wilcoxon test was used to analyze significant differences of detection rate of pain signs, OHIP scores and IED grade before and after restorations. Kaplan-Meier survival curve was used to describe the success rate, vital pulp survival rate, and tooth survival rate.

RESULTS

27 cracked teeth were restored with occlusal veneers with average of 22.4-month follow-up. Two cracked teeth had pulpitis and pain signs of the other cracked teeth completely disappeared. OHIP total scores were significantly reduced after treatment. Scores of 'pain', 'occlusal discomfort', 'uncomfortable to eat', 'diet unsatisfactory' and 'interrupted meals' reduced significantly after treatment. After treatment, IED grades of 25 vital teeth were significantly lower than those before treatment. FDI scores of 25 restorations except for 2 teeth with pulpitis were no greater than 2. The 12 months accumulated pulp survival rate of the cracked teeth was 92.6%. The 12 months accumulated tooth survival rate was 100%. The success rate at the latest recall was 92.6%.

CONCLUSION

Occlusal veneer restorations with success rate of 92.6% and the same pulp survival rate might be an effective restoration for treating the cracked teeth.

CLINICAL RELEVANCE

The occlusal veneer restorations might be an option for treating the cracked teeth when cracks only involve enamel and dentin, not dental pulp.

The treatment outcomes of cracked teeth: A systematic review and meta-analysis

OBJECTIVES

The aim of this review was to analyze the clinical treatment outcomes of cracked teeth (CT) retaining vital dental pulp (CT-VDP) or undergoing root canal treatment (CT-RCT).

SOURCES

A systematic search was conducted in Medline, Embase, PubMed, and Cochrane Library databases.

STUDY SELECTION

Studies evaluating tooth survival rate (TSR), pulp survival rate (PSR), and success rate (SR) with at least a one-year follow-up were included. The risk of bias was evaluated with the Newcastle-Ottawa scale.

DATA

Twenty-seven studies underwent qualitative analysis, 26 of which were included in the meta-analysis. SR of monitoring without restorative treatments was 80 % at three years. TSR of CT-VDP was 92.8-97.8 % at 1‒6 years, PSR of CT-VDP was 85.6‒90.4 % at 1‒3 years, and SR of CT-VDP was 80.6‒89.9 % at 1‒3 years; TSR of CT-RCT was 90.5‒91.1 % at 1‒2 years, and SR of CT-RCT was 83.0‒91.2 % at 1‒4 years. Direct restorations without cuspal coverage for CT-VDP increased the risk ratio (RR) of pulpal complications (RR=3.2, 95 % CI: 1.51-6.82, p = 0.002) and tooth extraction (RR=8.1, 95 % CI: 1.05-62.5, p = 0.045) compared with full-crown restorations. The CT-RCT without full-crown restorations had an 11.3-fold higher risk of tooth extraction than the CT-RCT with full-crown restorations (p < 0.001).

CONCLUSIONS

Monitoring without restorative treatments might be an option for the CT without any symptoms. Direct restorations without cuspal coverage for the CT-VDP could significantly increase the RR of pulpal complications and tooth extraction compared with full-crown restorations. Full-crown restorations are strongly recommended for the CT-RCT.

CLINICAL SIGNIFICANCE

Monitoring without restorative treatments could be a viable option for the CT without any symptoms. Full-crown restorations are strongly recommended for the CT with any symptoms and the CT-RCT.

A narrative review of cracks in teeth: Aetiology, microstructure and diagnostic challenges

OBJECTIVES

To summarize the available evidence of crack formation in teeth and to discuss the limitations of the current clinical diagnostic modalities for crack detection in teeth.

BACKGROUND

Cracks are a common clinical finding in teeth and yet clinicians still struggle to identify the full extent and orientation of cracks for their appropriate timely management. The biomechanics of crack development can be due to multiple factors and can differ from an unrestored tooth to a restored or endodontically treated tooth.

DATA & SOURCES

This narrative review has been designed following the guidelines published by Green et al. 2006 [1] Published literature in the English language that addresses the objectives of this review up to July 2022 was sourced from online databases and reference lists. The relevance of the papers was assessed and discussed by two reviewers. A total of 101 publications were included in this narrative review.

CONCLUSIONS

The initiation and development of cracks in teeth are likely linked to an interplay between the masticatory forces and fracture resistance of the remaining tooth structure. From the identified literature, the quality and quantity of remaining tooth structure in a restored or endodontically-treated tooth affects the biomechanics of crack development compared to an unrestored tooth. The extent, orientation, and size of the cracks do affect a clinician's ability to detect cracks in teeth. There is still a need to develop reliable diagnostic tools that will accurately identify cracks in teeth beneath restorations to enable effective monitoring of their propagation and provide appropriate interventions.

CLINICAL SIGNIFICANCE

The development and propagation of cracks in an unrestored tooth differ greatly from a restored and endodontically treated tooth; mainly linked to the quantity and quality of the remaining tooth structure and the forces acting on them. Identifying the extent of cracks in teeth remains challenging for early clinical intervention.

Lessons learned from the Cracked Tooth Registry: A 3-year clinical study in the Nation's Network

BACKGROUND

This article reviews the most salient lessons learned from a large, multisite, 3-year observational study of posterior teeth with cracks conducted by The National Dental Practice-Based Research Network.

TYPES OF STUDIES REVIEWED

Eight articles published over a 6-year period (2017-2022) describing clinical characteristics of posterior teeth with cracks and their treatment and outcomes are reviewed and discussed to answer 3 common questions faced by oral health care clinicians: Which cracked teeth will get worse? When should practitioners intervene? What is the best treatment?

RESULTS

Although cracks in teeth are prevalent, few will fracture (3%) or show crack progression in 3 years (12%). Characteristics that guide the clinician to treatment include active caries, biting pain, and to a lesser degree, having a crack detectable with an explorer, connecting with a restoration, or blocking transilluminated light; the main treatment chosen is a complete crown. Of those teeth treated (36%), few (14%) will need retreatment but will still survive, despite having an internal crack as well.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Although cracked teeth often pose a dilemma to clinicians, clincians are generally good at deciding which teeth to treat and when and which to monitor.

Stress intensity factor of a cracked molar restored with different materials and designs: A 3D-FEA

OBJECTIVE

This work used 3D finite element analysis (FEA) to analyze and directly compare the stress intensity factor (SIF) and stress distribution at the crack tip of identical cracked tooth models restored with different materials and crown parameters.

METHODS

A 3D model of the cracked tooth was generated. Then, we applied 25 restorative models, including three parameters (shoulder height, width, and degree of polymerization), five restorative materials (GC, IPS, LU, ZC, VE), and two combinations of types of cement (RMGIC and GIC). An occlusal load of 800N was applied to the spherical part along the longitudinal axis. The stress distribution of the preparation and the SIF of the crack tip was analyzed.

RESULTS

The crack tip SIF was minimal for a shoulder height offset of 0.8 mm (P = 0.032), a shoulder width of 0.6 mm (P = 0.045), a crown material of ZC (P < 2e-16), and a cement material of RMGIC (P < 0.05), respectively. In contrast, the effect of different polymerization degrees on SIF was insignificant (P = 0.95).

CONCLUSION

Our results suggest that the selection of a larger modulus of elasticity (MOE) material for the crown, the preparation of a smaller shoulder width within a safe range, a reasonable increase in the crown length, and the selection of adhesive materials with high fracture toughness are favorable methods to prevent further crack extension.

Evaluation of the clinical efficacy of quantitative light-induced fluorescence technology in diagnosing cracked teeth

BACKGROUND

This retrospective study evaluated the clinical efficacy of quantitative light-induced fluorescence (QLF) technology for crack detection and the diagnosis of cracked teeth and assessed the possibility of a quantitative evaluation of cracks using QLF technology.

METHODS

Patients who were clinically diagnosed with cracked teeth over a 1-year period were included. The QLF images of the corresponding symptomatic cracked teeth and asymptomatic contralateral teeth with crack lines were taken with Qraypen C (AIOBIO, Seoul, Korea). Fluorescence loss (ΔF), maximum fluorescence loss (ΔFmax), red fluorescence (ΔR), and maximum red fluorescence (ΔRmax) of the crack line were analyzed. The correlation between these parameters and sex, age, tooth position (1st premolar, 2nd premolar, 1st molar, 2nd molar), spontaneous pain (+/-), percussion test (+/-), cold test (++/+/-), and bite test (+/-) were statistically analyzed.

RESULTS

A total of 66 patients were included. Twenty-four patients had asymptomatic contralateral teeth with apparent crack lines; thus, 90 teeth were analyzed. The crack lines in 84 teeth observed as red fluorescent lines on the QLF images showed ΔR values higher than the cut-off value set by the analysis program used. The patient's age and the ∣ΔF∣ and ΔR values were positively correlated. However, there was no statistically significant difference in the QLF parameters between the same patient's symptomatic tooth and the contralateral tooth.

CONCLUSIONS

QLF technology is a useful assistive diagnostic device for diagnosing cracked teeth.

Treatment of cracked teeth: A comprehensive narrative review

Objectives

The term “cracked tooth” is used to describe an incomplete fracture initiated from the crown and progressing towards a subgingival direction. Despite the high prevalence of cracked teeth and their frequent association with symptoms and pulpal or periapical pathoses, there is still no consensus in the literature with regard to their restorative and endodontic management. Therefore, the aim of this narrative review was to evaluate the most relevant research and provide an up‐to‐date comprehensive overview regarding the treatment of cracked teeth.

Materials and Methods

An electronic literature search was carried out in MEDLINE (via Ovid), Embase (via Ovid), Scopus, and Web of Science as well as several “Grey literature” sources up to February 22nd 2022 using a combination of pre‐specified ‘free‐text' terms (keywords) and “subject headings.” The search process was supplemented by handsearching in relevant dental journals and reference lists. This narrative review focused on clinical follow‐up studies (observational or interventional studies, case series/reports), laboratory studies and systematic reviews written in English language that reported data on treatment of permanent cracked teeth. The selection of relevant studies was carried out by two reviewers (AK and DG) working independently in two consecutive stages: title/abstract screening and full‐text retrieval. Any discrepancies in the study selection were resolved by discussion between the reviewers.

Results

In total, 64 articles were selected for inclusion in this narrative review.

Conclusions

Cracked teeth with normal pulp or reversible pulpitis have exhibited high pulp and tooth survival rates by the provision of direct or indirect composite restorations. Besides, recent data favour monitoring, especially in the absence of symptoms or compromised tooth structure. When endodontic intervention is required, current evidence suggests that along with appropriate restorative management, outcomes of cracked teeth may be comparable to those of non‐cracked root filled teeth.

Onset and resolution of pain among treated and untreated posterior teeth with a visible crack: Three-year findings from the national dental practice-based research network

OBJECTIVE

Cracked teeth may be associated with pain, especially biting pain, and to a lesser degree cold and spontaneous pain.  Described are how commonly these pains remain constant, develop, or resolve over time, none of which have been well-described, especially among untreated cracked teeth.

METHODS

Cracked teeth from the Cracked Tooth Registry (CTR) study were followed for 3 years.  Assessments of cold, biting, and spontaneous pain and treatments performed were completed at enrollment (Y0) and at each annual recall visit.

RESULTS

209 practitioners enrolled 2,858 patients, each with a visible crack on a posterior tooth; 2601 (91%) patients attended at least one recall visit. Overall, 960 (37%) were treated, primarily with crowns. Among both treated and untreated cracked teeth with biting pain or spontaneous pain at Y0, the vast majority (92-99%) had their pain resolved by the time of a recall visit and 85-93% remained pain-free after initial resolution. The observations for cold pain were similar: 68% (untreated) and 78% (treated) became free of cold pain at some point during follow-up, and 84% of these stayed free of cold pain after initial resolution. Few teeth developed biting or spontaneous pain (4-8%) and 44-67% of these had pain resolution during the follow-up period.

CONCLUSION

In this study, treatment resolved a preponderance of pain associated with a cracked tooth.  Pain was also resolved for most untreated cracked teeth, especially biting pain, and to a lesser degree spontaneous and cold pain, although not to the same degree as with the treated cracked teeth.

Pathophysiology of Demineralization, Part I: Attrition, Erosion, Abfraction, and Noncarious Cervical Lesions

PURPOSE OF THE REVIEW

Compare pathophysiology for infectious and noninfectious demineralization disease relative to mineral maintenance, physiologic fluoride levels, and mechanical degradation.

RECENT FINDINGS

Environmental acidity, biomechanics, and intercrystalline percolation of endemic fluoride regulate resistance to demineralization relative to osteopenia, noncarious cervical lesions, and dental caries. Demineralization is the most prevalent chronic disease in the world: osteoporosis (OP) >10%, dental caries ~100%. OP is severely debilitating while caries is potentially fatal. Mineralized tissues have a common physiology: cell-mediated apposition, protein matrix, fluid logistics (blood, saliva), intercrystalline ion percolation, cyclic demineralization/remineralization, and acid-based degradation (microbes, clastic cells). Etiology of demineralization involves fluid percolation, metabolism, homeostasis, biomechanics, mechanical wear (attrition or abrasion), and biofilm-related infections. Bone mineral density measurement assesses skeletal mass. Attrition, abrasion, erosion, and abfraction are diagnosed visually, but invisible subsurface caries <400μm cannot be detected. Controlling demineralization at all levels is an important horizon for cost-effective wellness worldwide.

"THE CORRELATION OF CRACK LINES AND DEFINITIVE RESTORATIONS WITH THE SURVIVAL AND SUCCESS RATES OF CRACKED TEETH: A LONG-TERM RETROSPECTIVE CLINICAL STUDY"

INTRODUCTION

Cracked teeth (CT) frequently require protective adhesive restorations. This long-term, longitudinal retrospective clinical study aimed to evaluate the factors influencing the success and survival rates of CT with crack lines (CLs) in different directions, when restored early with onlays or full-coverage crowns.

METHODS

The dental records of 71 patients with a total of 86 CT, with different pulpal and periapical diagnoses, and with follow-ups spanning over 1-11 years were included. Data regarding the demographics; clinical symptoms and signs; bruxism; occlusal interferences; eating habits; pulpal and periapical diagnoses; number, direction, location, and extent of crack lines; probing depth; and coronary condition before and after the placement of definitive restorations were collected. Univariate associations between tooth survival and explanatory variables were assessed. The long-term survival rate was estimated using the Kaplan-Meier analysis and the log-rank test. A multivariate analysis was performed using Cox regression analysis.

RESULTS

The overall success rate was 93.0%, and the overall survival estimates of CT restored early were 98.6%, 94.9% and 55.9% at the 1-, 5-, and 11-year follow-ups, respectively. The direction of the CLs did not influence the survival of the tooth. No significant association was observed between the type of tooth, probing depth, root canal treatment (RCT), and tooth loss (P>0.05). The multivariate analysis showed that previously treated CT (P<0.05), provision of onlay restorations (P<0.05), and placement of posts (P<0.05) had higher correlations with tooth loss. Additionally, placement of full-coverage crowns resulted in lower tooth loss compared with the placement of onlays (P<0.05).

CONCLUSION

Previous endodontic treatment in teeth that subsequently develop CLs has a negative impact on the survival rate of the teeth. Moreover, early placement of full-coverage crowns should be implemented for CT, regardless of the direction or number of CLs, since it is associated with a higher cracked tooth survival rate.

Influence of additional apical enlargement on microcrack formation in root dentine: a micro-computed tomography investigation

OBJECTIVES

To assess the effect of additional apical enlargement using nickel titanium (NiTi) instruments on the incidence of microcracks using micro-computed tomographic analysis.

MATERIALS AND METHODS

Fifty-one premolars with single canals were enlarged to ProTaper Gold (PTG) F2 (25/08) (Dentsply Sirona), ProFile Vortex Blue (VB) 25/06 (Dentsply Tulsa), or WaveOne Gold (WOG) primary (25/07) (Dentsply Sirona) NiTi rotary instruments (n = 17 each). Afterward, additional apical enlargement was performed in each group with its corresponding larger instrument (F3 (30/09), VB 30/06, or WOG Medium (35/06) instruments, respectively). All teeth were imaged with micro-computed tomography before canal enlargement and after initial and additional apical enlargements to detect new microcracks at the apical 5 mm. An Aligned Rank Transform ANOVA was conducted to examine the effects of file type and canal enlargement on the number of new microcracks resulting from enlargement. A Kruskal-Wallis test was run to compare the file types at each canal enlargement stage.

RESULTS

A significant main effect (P = 0.026) of canal enlargement on the number of new microcracks was found; the number of apical microcracks found after additional enlargement was significantly greater than baseline (P = 0.021); no significant difference was found between baseline and initial enlargement (P = 0.506) and between initial enlargement and additional enlargement (P = 0.252). The Kruskal-Wallis tests found no difference between file types at baseline (P = 0.348), after initial enlargement (P = 0.369) or additional enlargement (P = 0.133).

CONCLUSIONS

Regardless of the instrumentation system used, additional apical enlargement led to the formation of high number of new microcracks.

CLINICAL SIGNIFICANCE

The results indicated that additional enlargement induced significant number of apical microcracks.

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.