The Epidemic of Cracked and Fracturing Teeth
Can earlier diagnosis, improved magnification and more conservative restorative strategies help us preserve vulnerable teeth?
Cracked teeth remain one of the more challenging areas of restorative dentistry. A tooth may appear clinically unremarkable while harbouring structural damage that is difficult to identify without appropriate examination.
In this influential 2007 article, Dr David Clark explores the factors contributing to tooth fractures, the diagnostic value of higher magnification and the importance of distinguishing superficial enamel cracks from structural dentinal fractures.
Figure 1 from Dr Clark's publication illustrates compromised posterior teeth, including a fracture occurring at tissue level.
Why Do Teeth Crack and Fracture?
Dr Clark's original article raised concerns about the structural integrity of posterior teeth and questioned whether conventional restorative approaches were contributing to the problem.
Longer Tooth Retention
As patients retain their natural teeth for longer, those teeth experience cumulative functional loading, wear and previous restorative interventions.
Occlusal Forces
Clenching, bruxism and concentrated occlusal loading may contribute to the development or progression of cracks in vulnerable teeth.
Traditional Cavity Preparations
Dr Clark questions the structural consequences of conventional G.V. Black-style preparations, particularly when large amounts of supporting tooth structure have been removed.
Extensive Dental Treatment
The article also discusses substantial crown reduction and aggressive endodontic shaping as potential contributors to structural weakening in selected teeth.
The key message:
Dr Clark argued that fracture prevention
should become a greater priority
in restorative dentistry.
The article challenges clinicians
to think not only about restoring
damaged teeth, but also about
preserving the structural integrity
of the remaining tooth.
The Power of Magnification in Crack Diagnosis
A central theme of the article is the importance of identifying potentially significant cracks before a tooth suffers a more extensive fracture.
Seeing What Conventional Examination May Miss
Traditionally, cracked teeth have frequently been investigated following the development of symptoms such as pain on biting or temperature sensitivity.
Dr Clark argues that waiting for symptoms can mean that structural damage has already progressed.
He describes how the use of an operating microscope allows clinicians to identify subtle crack characteristics that may be difficult to appreciate at lower magnification.
In particular, the article advocates examination at approximately 16× magnification, discussing a range of 13× to 18× for detailed visual assessment.
Higher magnification may reveal changes in colour, crack direction, surface characteristics and relationships to existing restorations.
What Should the Clinician Look For?
- Crack direction and overall configuration.
- Whether a crack changes width or direction.
- Localised discolouration associated with a crack.
- Relationships to existing restoration margins.
- Areas of enamel breakdown or ditching.
- Signs of possible underlying dentinal damage.
- The patient's symptoms, wear patterns and occlusal loading.
Clinical perspective:
Magnification can provide additional
visual information, but the appearance
of a crack alone does not establish
its depth, prognosis or treatment needs.
The findings must be interpreted
alongside the clinical history,
symptoms, examination and
other appropriate investigations.
Enamel Cracks and Dentinal Cracks Are Not the Same
One of Dr Clark's most important observations is that visible enamel cracks do not necessarily indicate an underlying structural fracture.
Enamel Cracks
Enamel cracks are common, particularly in older teeth.
Some appear as fine, superficial craze lines and may not extend significantly into dentine.
They may be associated with age, wear, restorative procedures or other factors.
Importantly, even a visually prominent enamel crack does not automatically indicate that a tooth is structurally compromised.
Careful assessment is needed to determine whether further investigation is warranted.
Dentinal Cracks
Cracks involving dentine are of greater structural significance.
Dr Clark describes two broad dentinal crack patterns:
Vertical cracks located around the pulpal floor, which he describes as pre-radicular.
Oblique cracks associated with cavity line angles or cusp structures, described as pre-cuspal.
These patterns may indicate incomplete fractures requiring further assessment.
Why the distinction matters:
Treating every visible enamel crack
as a structural fracture risks
unnecessary intervention.
Conversely, failing to recognise
significant dentinal damage
may allow further deterioration.
The challenge is identifying
which findings require monitoring,
investigation or restorative treatment.
Understanding the Three Types of Enamel Crack
In the original publication, Dr Clark proposes three categories of enamel crack based on visual characteristics and their potential association with underlying pathology.
Type I Enamel Cracks
The article describes these as having little or no apparent risk of underlying pathology.
Examples include:
- Simple vertical craze lines.
- Cracks following natural anatomical grooves.
- Superficial staining without other concerning features.
- Some enamel cracks associated with ageing.
Dr Clark discusses observation and preventive management as possible approaches.
Type II Enamel Cracks
These are described as having a moderate potential association with underlying pathology.
Examples include:
- Wedge-shaped enamel ditching.
- Cracks associated with localised wear facets.
- Ditching adjacent to existing restorations.
- Cracks that deviate from natural anatomical grooves.
Further investigation may be appropriate, including assessment of symptoms and existing restorations.
Type III Enamel Cracks
These are described as having a higher potential association with underlying structural pathology.
Examples include:
- Diagonal cracks branching from vertical cracks.
- Cracks extending from restoration corners.
- Cracks containing visible debris.
- Associated enamel discolouration or colour halos.
- Paired cracks outlining a compromised cusp.
The article recommends closer investigation for possible dentinal involvement and structural compromise.
Important:
These Type I, II and III categories
represent Dr Clark's proposed
visual classification from 2007.
They are useful for understanding
his diagnostic approach but
should not be interpreted
as a universally validated
modern risk-scoring system.
Definitive treatment decisions
require comprehensive
clinical assessment.
Understanding Tooth Fracture Patterns
The original publication uses clinical images and diagrams to illustrate the relationship between preparation geometry, crack development and structural failure.
Why Do Some Cracks Progress?
Dr Clark describes how repeated functional loading can contribute to the propagation of existing structural cracks.
The location and orientation of a crack, the remaining tooth structure and the presence of existing restorations all influence the clinical situation.
The article particularly questions the use of preparation designs that leave weakened cusps unsupported.
The published diagrams help explain why the author placed such emphasis on preserving tooth structure and identifying structural damage early.
A More Considered Approach to Crack Assessment
The appearance of a crack is only one part of the diagnostic process. A careful assessment brings together visual observations and the wider clinical picture.
Patient History
Establish the nature, duration and triggers of symptoms, including biting discomfort, temperature sensitivity and any relevant history of trauma or parafunction.
Clinical Examination
Examine existing restorations, wear facets, tooth anatomy and visible cracks. Appropriate magnification and illumination may reveal additional detail.
Structural Assessment
Consider the location of the crack, remaining cusp thickness, restorative history and any signs of underlying dentinal involvement.
Risk & Treatment Planning
Integrate examination findings with appropriate additional investigations, occlusal assessment and the patient's clinical circumstances before deciding on treatment.
Clinical emphasis:
A visible crack should prompt
thoughtful assessment, not
an automatic restorative
intervention.
The aim is to distinguish
superficial findings from
potentially significant
structural defects and
select management that
is proportionate to
the clinical risk.
Dr Clark's Five Proposals for Reducing Tooth Fractures
The original article sets out five areas Dr Clark believed dentistry should reconsider to improve the preservation of natural teeth. These are summarised below.
Earlier Diagnosis
Move away from exclusively symptom-driven diagnosis towards regular examination using higher magnification.
Rethink Cavity Preparation
Reconsider traditional posterior preparation designs and develop restorative techniques that better preserve tooth structure.
Conservative Endodontics
Re-examine endodontic access and shaping principles with greater consideration for remaining tooth structure.
Preserve Tooth Structure
Avoid unnecessary extensive reduction during indirect restorative procedures and consider conservative preparation designs.
Understand Occlusion
Give greater attention to functional loading, occlusal assessment, parafunction and appropriate protection of vulnerable teeth.
Historical context:
These five proposals were
presented in 2007.
They illustrate the author's
clinical thinking at that time,
rather than a contemporary
evidence-based treatment
guideline.
From Fracture Prevention to Modern Restorative Dentistry
Many of the questions raised in this early article help explain Dr Clark's subsequent interest in contemporary cavity design and the development of the Bioclear Method.
Preserving the Tooth-Restoration Complex
In 2007, Dr Clark challenged clinicians to reconsider why teeth fracture and how restorative dentistry might contribute to structural weakening.
His later work explores preparation designs that take greater account of the remaining tooth structure, adhesive materials and restorative geometry.
The Clark Class II cavity design and modern Bioclear restorative protocols reflect this wider interest in conservative treatment and anatomical reconstruction.
The Bioclear Method incorporates five core principles:
- Thorough biofilm removal before adhesive procedures.
- Contemporary preparation design that prioritises appropriate conservation of tooth structure.
- Anatomical matrix systems to guide restorative contours.
- Heated composite injection moulding using suitable materials and protocols.
- Systematic finishing and Rockstar Polishing.
These later developments should be understood as a continuation of the restorative philosophy, rather than techniques described in the original 2007 paper.
Read the Full Article by Dr David Clark
The Epidemic of Cracked and Fracturing Teeth
Dr David Clark, DDS
Dentistry Today, May 2007
Magnification
Four-page PDF
Explore the original discussion of microscopic examination, enamel and dentinal cracks, the proposed crack classification system and fracture prevention.
Frequently Asked Questions
Common clinical questions relating to cracked teeth, fracture diagnosis and conservative restorative treatment.
Does every visible crack require treatment?
No. Superficial enamel craze lines are common and do not necessarily indicate a structural dentinal fracture. The need for treatment depends on the clinical findings, symptoms, crack characteristics and overall tooth prognosis.
Can a tooth be cracked without causing pain?
Yes. Some teeth with visible or underlying cracks may be asymptomatic. However, the presence of a crack does not automatically mean that the tooth is at risk of catastrophic fracture. Careful assessment is required.
Why is magnification helpful when examining cracked teeth?
Magnification and illumination can help reveal subtle characteristics, including crack direction, associated staining and changes in enamel appearance. These observations can inform diagnosis when considered alongside symptoms and other clinical findings.
What is the difference between an enamel crack and a dentinal crack?
An enamel crack may be superficial and confined to the outer tooth structure. Dentinal cracks extend into the underlying dentine and may be more structurally significant. Their extent and clinical implications require appropriate investigation.
Can a cracked tooth be treated with composite?
Some cracked or structurally compromised teeth may be suitable for direct composite restorations or direct cuspal coverage. Other situations may require indirect restoration, endodontic treatment or extraction. The appropriate approach depends on the location and extent of the crack, pulpal and periodontal status, remaining tooth structure and occlusal factors.
Can conventional Class II preparations weaken a tooth?
Removing tooth structure can reduce the structural integrity of the remaining tooth, depending on the preparation size, geometry and location. Dr Clark's article questions whether traditional cavity designs adequately account for the mechanical behaviour of restored teeth.
How does the Bioclear Method relate to cracked tooth management?
The Bioclear Method uses contemporary preparation principles, adhesive techniques, anatomical matrices and composite injection moulding. These principles may be applied to selected posterior restorations, including cases requiring direct cuspal coverage. Suitability must be determined through individual clinical assessment.
Where can dentists learn advanced posterior composite techniques?
Bioclear Matrix UK offers hands-on education covering posterior restorative dentistry, including contemporary cavity design, Class II restorations and composite injection moulding. Our advanced education also explores the assessment and restorative management of more complex cases.
Continue Exploring Posterior Restorative Dentistry
Discover how the principles discussed in this early article connect with subsequent developments in modern cavity preparation and composite dentistry.
Develop a More Comprehensive Approach to Posterior Dentistry
Understanding tooth structure, preparation design and restorative anatomy is central to successful posterior composite dentistry.
Bioclear Matrix UK offers hands-on education covering contemporary cavity design, anatomical matrix systems, Class II restorations, composite injection moulding and advanced restorative problem-solving.
Explore our Introduction and Core Posterior courses and discover how the Bioclear Method can expand your clinical treatment options.