Cracked Teeth & Reversible Pulpitis: What Does the Research Tell Us?
A six-year evaluation of cracked teeth, treatment decisions and the subsequent need for root canal treatment.
Cracked teeth remain a common diagnostic and restorative challenge. When a cracked tooth presents with symptoms of reversible pulpitis, clinicians must decide whether restoring the tooth is sufficient or whether endodontic treatment may become necessary.
In this published clinical study, Dr Keith Krell and Dr Eric Rivera investigated cracked teeth diagnosed with reversible pulpitis and examined their outcomes following planned full-coverage crown restoration.
The findings provide useful information for discussions about cracked tooth prognosis, pulpal diagnosis and restorative treatment planning.
Eric M. Rivera, DDS, MS
Journal: Journal of Endodontics
Published: December 2007
Reference: Volume 33, Issue 12, pages 1405–1407
DOI: 10.1016/j.joen.2007.08.015
Results relate to teeth treated within a six-year study enrolment period. They are not six-year outcomes for each individual tooth.
Understanding the Six-Year Study
The research examined patients referred to a private endodontic practice over six years, identifying cracked teeth and evaluating those diagnosed with reversible pulpitis.
Important context:
The 9.7% incidence of identified
cracked teeth relates to patients
referred to a specialist
endodontic practice.
It should not be interpreted
as the prevalence of cracked
teeth in the general population.
What Were the Researchers Investigating?
The authors wanted to understand the clinical outcomes of cracked teeth initially diagnosed with reversible pulpitis and subsequently treated with full-coverage crowns.
In particular, they examined the proportion of patients who later developed irreversible pulpitis or pulp necrosis and required root canal treatment.
They also investigated the anatomical location of cracks, periodontal probing findings and changes in the clinical presentation of affected teeth.
How Were the Cracked Teeth Assessed?
Diagnosis involved clinical history, pulpal and periapical testing, periodontal examination and direct crack identification.
Pulpal & Periapical Assessment
Patient history, radiographs, cold and heat testing, percussion, palpation and periapical pressure were used in the diagnostic process.
The reversible pulpitis group included teeth with no spontaneous pain, brief cold sensitivity and no radiographic pathosis.
Crack Identification
Cracks were identified using transillumination and direct visual examination, with and without magnification.
The study required an identifiable crack that blocked light transmission and produced a definite shadow.
Crazing without this finding was excluded.
Probing & Bite Testing
Periodontal probing was performed around the teeth, including focused probing around identified marginal ridge cracks.
Bite responses were assessed on individual cusps using a burlew wheel or Tooth Slooth.
Full-Coverage Crown Restoration
Teeth meeting the reversible pulpitis criteria were planned for full-coverage crown treatment without initial root canal treatment.
Patients were generally recalled one year after treatment, unless root canal treatment was required earlier.
The researchers recorded any subsequent progression to irreversible pulpitis or pulp necrosis.
This distinction is important: the study evaluated a crown-first treatment approach. It did not investigate Bioclear composite injection moulding or compare direct composite restorations against crowns.
The Results: What Happened to the 127 Teeth?
The study found that most cracked teeth initially diagnosed with reversible pulpitis did not require subsequent root canal treatment during the reported follow-up.
Root Canal Treatment Outcomes
100 of the 127 teeth did not require root canal treatment during the reported follow-up.
27 of the 127 teeth subsequently developed irreversible pulpitis or pulp necrosis.
Source: Krell & Rivera, Journal of Endodontics, 2007. Percentages calculated from the 127 teeth diagnosed with reversible pulpitis.
Why Did Root Canal Treatment Become Necessary?
Of the 27 teeth requiring endodontic treatment, most progressed to irreversible pulpitis. A smaller group developed pulp necrosis.
Irreversible Pulpitis
21 teeth, representing 16.5% of the original 127-tooth group, progressed to irreversible pulpitis.
The average time to treatment was 58 days.
Pulp Necrosis
Six teeth, representing 4.7% of the original group, developed pulp necrosis.
The average time to treatment was 149 days.
No Subsequent RCT
The remaining 100 teeth did not require root canal treatment at the reported follow-up.
The study does not establish six-year outcomes for every individual tooth.
A useful clinical observation:
The authors found that
approximately one in five
cracked teeth diagnosed
with reversible pulpitis
required subsequent
endodontic treatment
following planned
crown restoration.
Most of these
endodontic interventions
occurred within the
first few months.
Which Teeth Were Most Frequently Affected?
The study also investigated the distribution of identified cracked teeth among different posterior tooth types.
Mandibular Second Molars
The most frequently identified cracked teeth in the referral population.
243 of 796 cases
Approximately 30%
of identified cracked teeth.
Mandibular First Molars
The second-largest group of cracked teeth identified in the study.
231 of 796 cases
Approximately 29%
of identified cracked teeth.
Maxillary First Molars
The third most frequently affected tooth type in the study.
167 of 796 cases
Approximately 21%
of identified cracked teeth.
Interpretation:
These figures describe
the distribution of cracked
teeth in the specific
specialist referral population.
They do not demonstrate
that an individual
mandibular second molar
is necessarily at greater
risk than every other
tooth type in the
general population.
Does Crack Location Influence Prognosis?
The study examined the location of marginal ridge cracks among teeth that subsequently required root canal treatment.
Mesial and Distal Marginal Ridge Cracks
Among the 27 teeth requiring root canal treatment, the authors recorded the following crack locations:
- Distal marginal ridge only: 15 teeth (56%).
- Mesial marginal ridge only: 4 teeth (15%).
- Both marginal ridges: 8 teeth (29%).
The authors noted that distal marginal ridge involvement was particularly common among teeth that subsequently required endodontic treatment.
However, the study did not establish a validated individual risk prediction model based on crack location.
Periodontal Probing Findings
The study also recorded localised changes in interproximal periodontal probing depth.
Only five of the 27 teeth requiring root canal treatment showed increased interproximal probing associated with the identified crack.
This represented approximately 4% of the original 127-tooth reversible pulpitis group.
The authors also reported that none of the teeth requiring root canal treatment had fractured so extensively that they were considered non-restorable.
Clinical significance:
Crack location, probing
findings and pulpal
symptoms all contribute
to assessment.
However, no single
examination finding
reliably determines
the future behaviour
of every cracked tooth.
What Do These Findings Mean for Clinical Practice?
This study provides useful information for managing expectations when a cracked tooth presents with reversible pulpitis.
Accurate Diagnosis Matters
Distinguishing reversible pulpitis from irreversible pulpitis or pulp necrosis is an important starting point when planning treatment.
RCT Is Not Always Necessary Initially
The study demonstrates that many appropriately selected cracked teeth did not require immediate endodontic treatment before crown restoration.
Patients Need Realistic Expectations
Even when reversible pulpitis is diagnosed, pulpal deterioration may occur following restorative treatment.
Patients should understand the possibility of subsequent root canal treatment.
What the Study Does — and Does Not — Demonstrate
The findings support the observation that many cracked teeth with reversible pulpitis can undergo restorative treatment without immediate root canal treatment being necessary.
However, the study was conducted within a specialist endodontic referral population and was observational.
It did not compare crown treatment against other restorative approaches, nor did it investigate different direct composite techniques.
Consequently, the results cannot establish that full-coverage crowns are superior to direct composite overlays, or that they are appropriate for every cracked tooth.
A key limitation: the six-year period refers to the study's patient collection period, not a six-year clinical follow-up of each restoration.
How Does This Research Relate to the Bioclear Method?
Although this publication does not investigate Bioclear, its findings are relevant to the wider clinical discussion surrounding cracked teeth, restorability and conservative dentistry.
From Diagnosis to Restorative Planning
The prognosis of a cracked tooth depends on more than the visible crack itself.
Pulpal status, tooth structure, crack location, periodontal findings and occlusal loading must all be considered during treatment planning.
In contemporary restorative dentistry, clinicians may also consider whether direct adhesive restoration or cuspal coverage is suitable for the individual tooth.
The Bioclear Method provides restorative techniques that can be applied to selected posterior teeth, including Class II restorations and direct composite overlays.
However, the results of this study cannot be used to claim equivalent outcomes for Bioclear restorations.
Clinical Considerations
- Establish a clear pulpal and periapical diagnosis.
- Assess crack location and potential extent.
- Evaluate remaining tooth structure and restorability.
- Consider whether cuspal protection is indicated.
- Review occlusal loading and functional factors.
- Discuss the possibility of future endodontic intervention.
- Select an appropriate restorative technique based on the individual clinical circumstances.
Why this research is useful:
Understanding cracked tooth
prognosis helps clinicians
make better-informed
restorative decisions
and communicate treatment
risks to patients.
This remains relevant
whether the final
restoration is direct
composite, an overlay
or an indirect crown.
Read the Full Journal of Endodontics Study
A Six Year Evaluation of Cracked Teeth Diagnosed with Reversible Pulpitis: Treatment and Prognosis
Keith V. Krell and Eric M. Rivera
Journal of Endodontics
December 2007
Volume 33, Issue 12
Pages 1405–1407
The downloadable PDF includes the original abstract, methodology, tables, results, discussion and references.
Frequently Asked Questions
Key questions about cracked teeth, reversible pulpitis and the clinical interpretation of this research.
What is reversible pulpitis?
Reversible pulpitis describes pulpal inflammation where recovery is considered possible following appropriate management of the cause.
In this study, diagnostic criteria included no history of spontaneous pain, brief cold sensitivity resolving within three to five seconds, and no radiographic pathosis.
Does a cracked tooth with reversible pulpitis always need root canal treatment?
No. In this study, 100 of 127 cracked teeth initially diagnosed with reversible pulpitis did not require subsequent root canal treatment during the reported follow-up.
However, 27 teeth did require endodontic treatment after progression to irreversible pulpitis or pulp necrosis.
Does the study demonstrate 78.7% success over six years?
No. The six years refer to the period during which patients were evaluated and entered the study.
The patients were generally recalled approximately one year after treatment unless root canal treatment was needed sooner.
The 78.7% figure represents the proportion of the 127 teeth that did not require subsequent root canal treatment during the reported follow-up.
How quickly did irreversible pulpitis develop?
Among the teeth progressing to irreversible pulpitis, the average time to root canal treatment was 58 days.
For teeth developing pulp necrosis, the average time was 149 days.
Which teeth were most commonly cracked?
In this specialist referral population, mandibular second molars were the most frequently identified cracked teeth, followed by mandibular first molars and maxillary first molars.
These findings describe the study population and should not be assumed to represent the general population.
How were cracks identified in the study?
Cracks were assessed through direct visual examination, transillumination, clinical testing and periodontal probing.
An identifiable crack was required to interrupt light transmission and create a visible shadow.
Teeth showing superficial crazing without this finding were not included in the cracked tooth study group.
Does the study show that crowns are better than composite overlays?
No. The study investigated cracked teeth diagnosed with reversible pulpitis that were planned for full-coverage crown restoration.
It did not include a comparison group treated with direct composite overlays or the Bioclear Method.
Therefore, it cannot establish which restorative approach provides superior outcomes.
Can Bioclear be used for cracked teeth?
The Bioclear Method can be used for selected posterior restorative situations, including direct cuspal overlays.
Whether this is appropriate for a particular cracked tooth depends on the pulpal diagnosis, crack extent, remaining tooth structure, occlusion and restorative requirements.
Where can dentists learn about managing cracked and compromised posterior teeth?
Bioclear Matrix UK provides hands-on education covering contemporary posterior composite restorations, anatomical matrices, conservative cavity preparation and injection moulding.
Advanced training also explores the assessment and management of more complex restorative cases.
Continue Exploring Cracked Teeth & Restorative Dentistry
Discover more clinical publications exploring tooth fracture, preservation of tooth structure and contemporary restorative techniques.
The Epidemic of Cracked and Fracturing Teeth
Dr David Clark explores crack diagnosis, magnification, fracture patterns and the importance of early clinical assessment.
Read the Article →Fracture-Resistant Endodontic & Restorative Preparations
Drs Clark, Khademi and Herbranson examine conservative cavity preparation, root anatomy, dentine preservation and fracture resistance.
Read the Article →Posterior Composite Restorations & Class II Contacts
Dr Claire Burgess and Professor Dominic Hassall explore contemporary cavity design, anatomical matrices and posterior composite injection moulding.
Read the Article →Develop Your Approach to Compromised Posterior Teeth
Understanding tooth structure, pulpal health, crack assessment and restorative biomechanics is essential when planning treatment for compromised posterior teeth.
Bioclear Matrix UK provides hands-on education covering contemporary cavity preparation, Class II restorations, anatomical matrices, direct composite overlays and heated composite injection moulding.
Explore our Core Posterior courses and advanced clinical training to further develop your restorative treatment options.
Research summary based on A Six Year Evaluation of Cracked Teeth Diagnosed with Reversible Pulpitis: Treatment and Prognosis by Keith V. Krell and Eric M. Rivera.
Journal of Endodontics, December 2007, 33(12):1405–1407. DOI: 10.1016/j.joen.2007.08.015
The study investigated full-coverage crown treatment. It did not evaluate Bioclear composite restorations or establish comparative effectiveness between restorative techniques.