Fractured First Upper Pre-Molar Restored with Resin Composite CASE REPORT

Mireille Feghali BDS, DU Assistant, Department of Restorative and Esthetic Dentistry, Lebanese University, Beirut - Lebanon Emilie Mouchantaf BDS, DU Assistant, Department of Restorative and Esthetic Dentistry, Lebanese University, Beirut - Lebanon Paul Nahas BDS, CES Chief of Services, Department of Restorative and Esthetic Dentistry, Lebanese University, Beirut - Lebanon CES from Claud-Bernard University, Lyon-France

ABSTRACT The lack of knowledge of the biomechanical response of a vital tooth restored with composite makes the practitioners tend for full coverage instead of a partial restoration. The purpose of this article is to show that a large composite restoration on a vital tooth is always possible. Although the risk of fracture of the remaining enamel walls, even if they are well supported, is relatively high. The line of the fracture, because the tooth is still vital, should stay above the pulp chamber. No other fracture at the root level was observed. Three years later the tooth is still functional.

KEYWORDS Cracked tooth, Dental restoration, Bonding composite.

INTRODUCTION CASE REPORT Unlike what is known, teeth are not rigid structures; they This article is a case report of a fractured first upper undergo deformation during normal loading, and lead pre-molar that held a critically composite restoration for in some situations to weaken or even to lose parts. The almost 5 years. main factors that contribute to common tooth fracture are: masticatory accidents, such as biting on a hard, rigid The following case compared the bonding resistance object with unusually high force, or excessive removal throughout the years between dentin and enamel. of tooth structure during cavity preparation, extensive A 41-year-old female exhibited discomfort at the upper composite restorations placed without due care for left maxillary region. incremental technique, as well as large Class II OM and She was having pain especially when chewing tough MOD restorations that produce obvious deformation. foods and often something as innocuous as salad, and By definition, tooth fracture is a fracture plane of sudden onset of acute sensitivity to thermal changes, unknown depth and direction passing through tooth always to cold and sometimes to heat. structure,1 while infraction is when the crack line is limited only to the enamel2 the most commonly affected The clinical examination revealed a horizontal line of teeth are mandibular second molars, followed by crack at the palatal side of the tooth (Fig 1). mandibular first molars and maxillary premolars.3 No other fracture was detected after a circumferential J. Edward Ailor JR has classified fractures into vertical or periodontal probing of the sulcus. The gum around the oblique. Vertical fractures are located midtooth, usually tooth looked healthy. running in a mesiodistal direction, although buccolingual Although various fracture detection devices test individual vertical fractures do occur. Oblique fractures normally cusps to localize fractures, biting on cotton rolls is originate at the internal line angles of intracoronal considered the simplest method and it revealed the same preparations and result in cuspal fracture, with or without pain described by the patient. X-ray under magnifying root involvement.1 loupes clarifies the diagnosis by exposing the fracture According to Lynch C et al. management options line and its extent (Fig 2) even though a radiograph is of a cracked tooth vary according to clinical need, not the primary diagnostic aid for locating fractures. from replacement of the fractured cusp with a simple restoration to placement of an extracoronal restoration Primary Treatment with adequate cuspal protection.4 Like any other treatment, the fractured part should be

| 56 | Smile Dental Journal | Volume 7, Issue 1 - 2012 eliminated in order to relieve pain.

It is well known that Pressure applied to the crown of a cracked tooth leads to separation of the tooth components along the line of the crack.4 As a result, the whole crown, while removing the existing old restoration with a regular-grit diamond bur (Diamond Point FG, #104R, Shofu, Kyoto, Japan) in a high-speed hand piece under copious water spray, is detached taking off the buccal cusp with it (Fig 3).

Less than 25% of the detached fragment is composed of enamel and the rest is resin composite (Fig 4). The enamel is fractured before it can detach from the residual composite. (Fig 1) Cervical crack line of the palatal cusp On the other hand, the rest of the tooth shows a sclerotic pigmented dentin due to an old amalgam restoration (Fig 5). No evidence of any caries or residual composite material is visible. The fracture pattern shows a complete debonding of the restoration from the dentin.

Since partial restoration of the tooth with a composite is not feasible anymore; the patient is referred to a (Fig 2) X-ray showing the extent of the fracture line prosthodontist for full crown coverage.

Two weeks later endodontic treatment was performed and a metal screw was cemented. Then one month later the final crown was placed.

Figure 6 shows a 3 years follow up of the adaptation of the crown. The tooth is still functional.

DISCUSSION Posterior teeth, particularly maxillary premolars, have an anatomic shape that makes them more susceptible to cusp fractures when under occlusal load.5 Premolars are more brittle when subjected to lateral forces during mastication.

The type and quality of the remaining structure also has an influence on fracture resistance when the tooth is submitted to load application.

When the width of the intracoronal preparation of a posterior tooth exceeds one third of the intercuspal width, the tooth becomes significantly more susceptible to cuspal fracture and the concern becomes not only (Fig 3) Detached crown at the fracture line restoration failure but also tooth fracture.6

Cavities of large size (a facio-lingual dimension of more than two thirds of the distance between cusps) had been judged to require cusp covering.7

Thus, direct composite restorations are commonly used for small posterior restorations and are not recommended for large ones especially in regions with high masticatory forces.8

Although a cusp reduction of at least 1.5mm is recommended in extensive premolar restorations.9 The fractured tooth shows no reduction of the buccal cusp (Fig 4) Detached Fragment detail

Smile Dental Journal | Volume 7, Issue 1 - 2012 | 57 | chewed.10 Finally, it holds the fracture location above the pulp chamber at the lowest resistant wall which is in our case the floor of the restoration. No other fracture was observed in the remaining tooth especially at the level of the root for the last 3 years following the placement of the crown, means that the original fracture of the cusp was limited above the pulp chamber (Fig 7).

In this case the failure mode observed was the debonding of the restoration at the dentin bonding interface, this could be explained by the difference in the resistance fatigue with time of the bonding agent between enamel and dentin. Moreover, the resistance fatigue of the bonding agent with enamel is much better than the glasslike dentin (Fig 5), because it has a morphological and structural transformations, induced by physiologic and pathologic processes, resulting in (Fig 5) Sclerotic pigmented dentin a dentinal substrate that is less receptive to adhesive treatments than is normal dentin.6

CONCLUSION Diagnosing discomfort sometimes could be tricky. The practitioner must take into consideration among the other causes of pain the possibility of a tooth fracture, especially when patients complain of pain or discomfort while chewing or biting. A typical examination starting with the history to the clinical and radiographic inspection, finalized with specialized tests could be conclusive. Dependent on the type of the fracture, treatment could vary from partial (Composite, amalgam) to a full covered tooth restoration mainly when no more healthy residual structures are left. Based on a systematic examination and the awareness of the problem, the practitioner should have no difficulty diagnosing and managing pain caused by a fractured tooth. (Fig 6) Three years later the crown is still functional REFERENCES and yet it remained functional 1. J. Edward Ailor JR. Managing Incomplete Tooth Fractures. J Am for more than 5 years. Dent Assoc. 2000;131(8):1168-74. 2. Asbjorn Jokstad Stephen Bayne Uwe Blunck Nairn Wilson. Quality of dental restorations. International Dental Journal. (Fig 7) Considering all of these No other 2001;51(3):117-58. fractures factors, it looks obvious 3. Braly RV, Maxwell EH. Potential for tooth fracture in restorative dentistry. J Prosthet Dent. 1981;45(4):411-4. at the root that the restoration of such 4. Lynch C, McConnell R, The Cracked Tooth Syndrome. J Can Dent level, 3 fractured tooth is considered Assoc. 2002;68(8):470-5. years after a successful since it lasted 5 5. James D. Bader; Daniel A. Shugars; Jean A. Martin. Risk indicators placing years. The only reason that for posterior tooth fracture. JADA. 2004;135:883-92. the crown defends such treatment is 6. William F. Rose Jr., Carl W. Haveman, Richard D. Davis. Patient evaluation and problem-oriented treatment plan. In: James the vitality of the tooth, since B. Summitt and Coll. Fundamentals of Operative Dentistry a Dehydrated human dentin contemporary approach, third edition. Quintessence 2006, p.56. (like endodontically treated 7. Ulla Pallesen, Vibeke Qvist. Composite resin fillings and inlays. An 11-year evaluation. Clin Oral Invest. 2003;7:71-9. tooth) demonstrates lower strain values at fracture than 8. Duke ES, Robbins JW, Trevino D. The clinical performance of a new hydrated dentin. The mean value of Young’s modulus adhesive resin system in Class V and IV restorations, Compendium. of elasticity and the proportional limit in compression 1994;15:852-6. appears lower in pulpless teeth than in teeth with pulp. 9. Yen-Hsiang Chang, Mechanical interactions of cuspal-coverage designs and cement thickness in a cusp-replacing ceramic The pulps of human teeth have been found to contain premolar restoration: a finite element study, Med Biol Eng Comput. mechanoreceptors that are used to subconsciously 2009;47:367-74. limit the maximum biting force and consciously detect 10. Thomas D. Larson. Part One: The Restoration of Non-Vital Teeth: differences in the hardness of the objects being Structural, Biological, and Micromechanical Issues, in Maintaining Tooth Longevity. 2006;85(5):29-35.

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