Approaches to Managing Asymptomatic Enamel and Dentin Cracks Samer S

Fissurotomy (Micro) Dentistry

Approaches to managing asymptomatic enamel and dentin cracks Samer S. Alassaad, DDS

Asymptomatic enamel and dentin cracks can pose a risk for multiple cracks is crucial to adopting a proactive approach of prevention, early pathological and undesired consequences if intervention is postponed. diagnosis, and intervention to control the potentially detrimental effects This article reviews asymptomatic enamel and dentin cracks, and presents of these cracks on the dentition. current management approaches utilized by a sample of general dentists. Received: June 3, 2013 Becoming familiar with all forms of asymptomatic enamel and dentin Accepted: September 3, 2013

n incomplete tooth fracture, also year.7,9 Finally, Braly & Maxwell concluded enamel and dentin cracks, and conducted a known as a tooth crack, is a fracture that fractures are the third most common survey using clinical images during multiple without visible separation of the cause of tooth loss behind caries and perio- presentations to determine how general A 1 10 segments along the plane of the fracture. dontal disease. dentists currently manage these cracks in Incomplete tooth fractures can be subtle Based on the evidence that incomplete their general practice. and difficult to diagnose, especially when tooth fractures can lead to major compli- asymptomatic. However, they pose a risk cations, and taking into consideration that Materials and methods for multiple pathological and undesired the incidence of fractures increases with The author gave presentations on man- consequences that can eventually render age, a more proactive approach, in which aging incomplete tooth fractures to 4 the tooth unsavable. asymptomatic cracks are addressed early— different groups of dental professionals The pathological consequences can before major complications occur—should in Northern California between March range from caries to pulpal and perio- be considered. This is especially relevant 2012 and March 2013. A total of 71 dontal involvement to complete tooth with the current aging population.7,10,11 dental professionals—54 general dentists, fracture.2-8 Walker et al demonstrated that However, there has been less agreement 15 dental specialists, and 2 dental hygien- enamel cracks provide caries-producing among dentists on which teeth are at risk ists—attended these presentations. At the bacteria access to the dentin-enamel junc- of fracture, and which teeth require inter- beginning of the presentations, clinical tion, thus leading to caries progression vention for the prevention of fracture.12 photographs of asymptomatic enamel inside the tooth without any externally A recent literature review concluded that and dentin cracks in posterior teeth were visible evidence.2 Abou-Rass suggested that there is no universally accepted restorative projected on a screen to ensure unifor- asymptomatic crack lines are precursors to protocol to treat cracked tooth syndrome.13 mity in the referenced cases. Enamel and the symptomatic cracked tooth syndrome.3 Consequently, this author conducted a dentin cracks were classified according Krell & Rivera found a 9.7% incidence literature review of managing asymptomatic to their direction (vertical or oblique) of cracks in all teeth referred to an end- odontic practice within a 6-year period, excluding cusp fracture, vertical root fracture, and split teeth.5 In their study, 20% of the cases diagnosed as cracked teeth with reversible pulpitis and treated with full crown restorations nevertheless progressed to irreversible pulpitis or to necrotic pulp within 6 months.5 Pitts & Natkin described periodontal involvement associated with tooth cracks as bone loss produced by chronic inflammation along the fracture line, causing a narrow isolated pocket and radiographically linear bone loss along the root surface.6 In a study of cusp fracture in restored posterior teeth, Bader et al concluded that incomplete fractures are a predictor of complete cusp Fig. 1. Mandibular left first molar, lingual view. Fig. 2. Maxillary left first molar, buccal view. Oblique fractures, which have been found to have Stained enamel crack detectable by an explorer. enamel crack originating from the corner of restora- an incidence of 69.9/1000 persons each tion and detectable by transillumination.

58 November/December 2014 General Dentistry www.agd.org Fig. 3. Mandibular left second molar, buccal view. Left. Unstained vertical enamel crack. Right. The crack Fig. 4. Mandibular right second molar, occlusal accepts methylene blue dye. view. Stained vertical enamel crack undetectable by an explorer.

Fig. 5. Maxillary right second molar, occlusal view. Left. Unstained vertical enamel crack detectable by Fig. 6. Mandibular right first molar, occlusal view. transillumination. Right. The crack does not accept methylene blue dye. Stained vertical dentin crack.

and the presence of stain. Enamel cracks results. Of the 54 responses from general to explore for oblique enamel cracks were additionally classified based on their dentists, 3 were excluded as their answers originating from the corner of restora- detection by tactile examination with an were incomplete; descriptive statistics of tions and detectable by transillumination explorer, transillumination, and staining responses from the remaining 51 general (Fig. 2). Twenty-nine percent would with methylene blue dye. All attendees dentists were then computed. recommend removal for vertical enamel were then asked to answer multiple choice cracks that were unstained but accepting questions regarding the approaches they Survey results methylene blue dye (Fig. 3); 25% would utilize in their practice to manage the The majority of the general dentists recommend removal for vertical enamel projected asymptomatic enamel and (73%) would recommend to their cracks that were stained but undetect- dentin cracks, such as when and what they patients the removal of intracoronal res- able by an explorer (Fig. 4); and 12% recommend for intervention. To preserve torations in order to explore the extension of the general dentists surveyed would anonymity, participants were asked not to of asymptomatic vertical enamel cracks recommend the removal of intracoronal write their names on their answer sheets. in posterior teeth when these cracks restorations to explore for unstained Some of the dental specialists who attended were both stained and detectable by an vertical enamel cracks that were detect- the presentations limited their practice to explorer, even though the restorations able by transillumination but were not their specialty and did not directly treat were not compromised and the teeth had accepting methylene blue dye (Fig. 5). asymptomatic cracks. Seven dental special- no evidence of decay (Fig. 1). This was Twenty percent of participants would not ists and 2 dental hygienists did not com- followed by 62% of the general dentists recommend the removal of intracoronal plete the survey. Therefore, only responses who would recommend to their patients restorations to explore the extension of from general dentists were included in the the removal of intracoronal restorations asymptomatic enamel cracks.

www.agd.org General Dentistry November/December 2014 59 Fissurotomy (Micro) Dentistry Approaches to managing asymptomatic enamel and dentin cracks

Fig. 7. Mandibular right first molar, occlusal view. Fig. 8. Maxillary left first molar, occlusal view. Fig. 9. Mandibular right first molar, occlusal view. Stained oblique dentin crack. Unstained vertical dentin crack. Unstained oblique dentin crack.

Table. The treatment of choice (TOC) for asymptomatic vertical and oblique With regard to asymptomatic dentin dentin cracks chosen by general dentist survey participants (n = 47). cracks, 86% of general dentists in the sample would recommend treatment for TOC for vertical TOC for oblique stained vertical dentin cracks (Fig. 6) and dentin cracks (%) dentin cracks (%) 84% would recommend it for stained oblique dentin cracks in posterior teeth Full crown restoration 51 40 (Fig. 7), followed by 65% for both Indirect occlusal coverage restoration 19 32 unstained vertical dentin cracks and for (such as porcelain onlay restoration) unstained oblique dentin cracks (Fig. 8 Direct bonded composite intracoronal restoration 17 13 and 9). Eight percent of the general den- Direct occlusal coverage restoration 4 2 tists surveyed would not recommend any (such as bonded composite onlay restoration) treatment for asymptomatic dentin cracks. a Participants were then asked to rank their Protective occlusal hard bite plate 21 23 treatment approaches (restorative and/or Occlusal adjustment of opposing tootha 17 17 occlusal) for asymptomatic vertical and Occlusal adjustment of cracked tootha 13 19 oblique dentin cracks noted after restora- aOcclusal treatments were mainly chosen as the TOC in conjunction with restorative treatments. As a result, the tion removal, regardless of the relationship responses do not add up to 100%. between isthmus width and cusp-to-cusp distance. Participants were able to give the same ranking to multiple treatment approaches if they would recommend them simultaneously, such as occlusal treatments to diagnose. They can be evaluated by Clark et al classified asymptomatic enamel in conjunction with a restorative approach. transillumination, staining with dyes cracks based on the risk of underlying The treatments of choice (TOC) for the such as methylene blue dye, and tactile pathologies such as dentin cracks, decay, 47 general dentists who treat asymptomatic examination with a sharp explorer.14-16 and severely undermined enamel that allow dentin cracks are presented in the Table. Visual examination can also be enhanced microleakage.17 According to their analysis, The majority of participants were in favor by magnification with tools such as cracks with wedge-shaped enamel ditching of occlusal coverage restorations, such as magnifying loupes, intraoral photography, and cracks that either detour from or do full crown and onlays. Protective occlusal and microscopes.14,15,17 not follow anatomic grooves have a moder- hard bite plates and occlusal adjustments ate risk of underlying pathology.17 Diagonal of opposing and cracked teeth were the pri- Management of asymptomatic cracks, cracks that house debris, and cracks mary TOC when used in conjunction with enamel cracks with a brown, gray, or white correspond- restorative treatments. The traditional classifications of cracks ing “halo” have a high risk of underlying placed less emphasis on the possibility of pathology.17 The greater the risk, the more Literature review underlying pathologies of enamel cracks.17 strongly it is recommended to remove the Diagnosis of asymptomatic cracks Fortunately, more modern approaches restoration for further evaluation, followed Asymptomatic enamel and dentin are taking asymptomatic enamel cracks by treatment of any underlying pathology as cracks can be very subtle and difficult into consideration. needed, even if the tooth is asymptomatic.17

60 November/December 2014 General Dentistry www.agd.org In their study of cusp fracture in asymptomatic cracks to limit their pro- The susceptibility of teeth to fracture restored posterior teeth, Bader et al con- gression and thus prevent any subsequent has been measured in terms of isthmus cluded that external fracture lines that are undesired consequences.4 width in relation to cusp-to-cusp dis- detectable with an explorer should be con- Occlusal adjustment has been recom- tance.24 If teeth have been weakened due sidered strong indicators of elevated risk of mended as an initial treatment for cracked to wide cavity preparations, they need to complete fracture.7 However, it has been tooth syndrome.4 Although there is no be stabilized via indirect restorations, such emphasized that even dramatic enamel universally accepted restorative protocol as full cuspal coverage or bonded inlays.25 cracks may not necessarily indicate the in the treatment of symptomatic cracks, However, the isthmus width is not the only presence of any underlying pathology.8,17 it is generally agreed that the aim of factor that needs to be considered. The Ratcliff et al classified posterior enamel restorative therapy is to immobilize the depth of the restoration along the isthmus cracks based on the presence of stain and segments of the tooth that tend to move width can be a more accurate measurement restorations, and suggested that stained during loading.13 Opdam et al found that of the lack of dentin support.7 cracks are most likely to be treated due to direct composite restorations maintained Recent research has shown that the their appearance.11 The authors also con- the pulp vitality of >90% of cracked, prevalence of cusp fractures in amalgam cluded that equilibrating the occlusion for painful teeth, resulting in a complete restored teeth was found not to be sig- maximum intercuspation and eliminating elimination of pain in 75% of the affected nificantly different than resin composite excursive interferences may prevent the teeth over a 7-year period.18 The authors restored teeth.26 These new findings may propagation of asymptomatic cracks.11 also had more success with cuspal cover- further shift the emphasis away from Walker et al also suggested that stained age than without.18 Modern approaches treatment plans that are based mainly cracks should be considered as permeable advocate reinforcing resin-based restora- on the choice of restoration materials, as or permeated by cariogenic bacteria, and tions with leno-weave ultra high modulus these may result in designs that weaken that cracks displaying a shadow under polyethylene ribbon fibers in order to the teeth. Conservative cavity prepara- transillumination indicate the presence of bridge cracks and strengthen teeth against tions that preserve tooth structure without caries.2 Intervention is recommended for fractures.19,20 Crown restorations were connecting multiple occlusal preparations these cracks to block bacterial invasion and successful in maintaining pulp vitality have been advocated.17 Additionally, stop the progression of caries.2 in 80% of cracked teeth diagnosed with rounded internal line angles have been rec- reversible pulpitis over a 6-year period.5 ommended over sharp line angles to avoid Management of asymptomatic Additionally, altering traditional crown stress concentrations.23 dentin cracks preparations (such as beveling fractured Nonrestorative approaches have also Taking a more proactive approach of cusps), using bases and build-ups under been recommended to prevent cracks. assessing enamel cracks based on the pos- crown restorations, and placing margins Occlusal adjustment of nonfunctional sibility of underlying pathologies—such as more apically were suggested to minimize cusps of teeth predisposed to cracking— dentin cracks—brings another dilemma to external forces and prevent the propa- such as teeth with excessive cuspal wear, practitioners regarding what to do when an gation of fractures underneath crown heavy wear facets, worn restorations, or asymptomatic dentin crack is discovered. restorations.21 Additional clinical trials posterior malocclusion—has been recom- Dentin cracks should be considered comparing these direct and indirect treat- mended, especially when the patient has structural cracks and therefore protection ment options are required to determine a history of cracked tooth syndrome.4 from occlusal forces to minimize fracture the best treatment for the various forms of Although occlusal guards have not been propagation is indicated.3,8,17 However, incomplete tooth fractures.18,22 directly linked to preventing cracks and Clark et al speculated that intracoronal limiting their progression, they are con- restorations and occlusal adjustments Prevention of cracks sidered useful protectors of teeth against might be proven insufficient to stop struc- Whenever possible, the proactive pre- the damage caused by bruxism. Thus they tural breakdown associated with cracks, vention of tooth cracks is the optimal are an option worthy of consideration in and that occlusal coverage is mandatory.17 treatment choice. This requires a deep patients with a history of symptomatic Replacing an asymptomatic cracked cusp understanding of the etiology of tooth cracks and evidence of bruxism.27 with a restoration when 1 cusp is involved cracks in an effort to control the con- has been recommended.8 When more than tributing factors to their formation. The Summary 1 cusp is involved or there are asymptom- etiology of teeth cracks is complex and The majority of the general dentists who atic vertical cracks, placing a full crown multifactorial; Lynch & McConnell completed this survey would recom- restoration is recommended.3,8 proposed 10 factors that contribute to mend intervention for some forms of Currently the literature—including cracked teeth, citing 17 examples.23 The asymptomatic enamel cracks, but were clinical trials—focuses mainly on the treat- most commonly emphasized etiologic more proactive when it came to treating ment of symptomatic cracks. However, factors are the loss of dentin support due asymptomatic dentin cracks, emphasizing the principles used to treat symptomatic to relatively large intracoronal restora- restorations that provide occlusal cover- cracks can be applied to the treatment tions, and traumatic occlusal forces, age. Becoming familiar with the existence of asymptomatic teeth predisposed to especially when accompanied by excur- of all forms of asymptomatic enamel and cracking; this includes the treatment of sive interferences.4,7,11 dentin cracks, the modern methods of

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