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Case report: management of crown-root fracture in mandibular first primary molar caused by injury to the chin.


Dental trauma represents a widespread clinical and dental public health problem in young populations [Rodriguez, 2007]. Crown-root fractures are rarely seen following dental traumas [Bastone et al., 2000]. They are defined as injuries involving the enamel, dentine, cementum and sometimes pulp. According to Andreasen, they can be subclassified as complicated and uncomplicated based on pulpal involvement [Andreassen and Andreassen, 1994].

Crown-root fractures are very rare in the primary dentition with a prevalence of 2%. It is even rarer in primary molars with a reported incidence of 0.8% of all injured primary teeth [Andreassen and Andreassen, 1994]. Besides causing pain, traumatic injuries of primary teeth can affect normal function, aesthetics [Rajab, 2003] and the developing tooth germ [Diab and elBadrawy, 2000]. Complicated crown-root fractures often require complex treatment planning. Most of the reported cases of crown-root fractures have undergone extraction followed by space maintainers [Needleman and Wolfman, 1976; Morisaki et al., 1989; Gotze Gda et al., 2008; Tejani et al., 2008]. This article describes the diagnosis and treatment of an unusual case of complicated crown-root fracture and an alternate treatment option in a primary molar.

Case report

A 4-year-old girl was referred to the Specialty Dental clinic with her mother by the general dentist. The history revealed that ten days earlier, the patient had slipped while climbing down a ladder and received an impact on her chin resulting in a laceration. Following admission to hospital, neurological damage was ruled out, and the patient was treated for immediate emergency management. The medical history of the patient was non-contributory. Chin laceration was sutured in the trauma centre, but no dental treatment was carried out. She was subsequently discharged. Subsequently she had momentary pain in her left posterior teeth region while biting. This was exacerbated while eating and drinking and associated with disturbed sleep. The patient reported to the general dental practitioner and referred to the 'kidznteenz' Specialty Paediatric centre.

Clinical examination: Medically, the patient was fit and healthy. Extra-oral examination demonstrated a healing laceration on the chin (Figure1a). Mouth opening was normal and there was no pain on examination of the temporomandibular joints. The patient was very anxious due to a lack of dental experience and the obvious sensitivity of the teeth. Oral hygiene was poor with profuse plaque deposits, especially in the posterior region (Figure 1b). All primary teeth were present, with no associated carious lesions. A routine radiographic examination was carried out. Orthopantamogram (OPG) showed (Figure 1c) a radiolucent line in relation to the left mandibular primary first molar (74) which was running obliquely from occlusal to gingival involving enamel, dentine, cementum and close to the pulp in the mesial aspect. Based on the clinical and radiographical findings the complicated crown-root fracture of 74 was made.


Treatment. Since the fracture involved only one tooth, treatment was carried out under local anaesthesia even though the patient was a little anxious. The tooth was isolated with rubber dam thereby stabilising with the rubber dam clamps. Access was prepared in the conventional way. Canal patency was initially carried out with a size 15 'K' file. Canals were cleaned and shaped with Ni-Ti control hand piece (Anthogyr, Dentsply) and filled with Metapex (Meta Dental New York, Elmhurst, USA). The pulp chamber was restorative with glass ionomer cement (3M, ESPE, USA). As the fragments were stabilised, bleeding was considerably less. Immediately the crown preparation was carried out and fitted with a preformed metal crown (Figure 2). The gingival margin of the crown was placed well below the fracture line especially on the mesial side. Her parents were instructed to apply 0.2% chlorhexidine mouthwash (Hexidine, ICPA Health Products Ltd., Ankleshwar, India) with gauze swab to aid in plaque control. Post-operative review revealed no signs of discomfort after 3 days.

Follow-up. On a recall visit three months later, there was no clinical or radiographic pathology. The obturating material within the canals of 74 was intact. However, 12 months later, an intra-oral periapical radiograph (IOPA) and Orthopantamogram (OPG) showed complete resorption of the filling material from the canals of the molar (Figure 3a-b). In spite of this intra-radicular resorption of the obturating material, there were no clinical (Figure 3c) or radiographic signs of treatment failure. The patient was placed on a six month recall schedule.

Discussion. It is well-known that an impact on the resilient bones supporting the primary dentition often results in a dental displacement rather than damage to the hard tissues [Bennet, 1963]. Therefore, crown and crown-root fractures are uncommon in the primary dentition [Andreassen and Andreassen, 1994]. According to some authors [Needleman and Wolfman, 1976; Morisaki et al., 1989] posterior tooth fractures may not be detected in an emergency examination after the accident, but only be diagnosed later, when the patient begins to complain of pain. Though trauma occurs predominantly in the anterior region, to achieve an accurate diagnosis, it is vital to examine the posterior teeth, especially when there has been an injury to the chin [Needleman and Wolfman 1976; Morisaki et al., 1989]. On visual and radiographic examination, fracture lines are often difficult to detect and patient's anxiety may make it even more difficult to obtain a precise diagnosis especially in young children. The present case confirms this observation.

Techniques such as transillumination, staining of the teeth with disclosing solution, bite tests where the patient is instructed to bite on various items such as a toothpick, cotton roll, burlew wheel, wooden stick [Ehrmann and Tyas, 1990; Lynch and McConnell, 2002] or the commercially available Tooth Slooth [Professional Results, Inc., Laguna Niguel, California, USA] can be used to recognise fracture lines. For fractures, "bite tests" are conclusive [Lynch and McConnell, 2002]. The incidence of mandibular posterior tooth fracture may be associated with their proximity to the temporo-mandibular joint [Cameron, 1964; Ehrmann and Tyas, 1990]. It is based on the principle of the "lever" effect, the mechanical force on an object is increased at closer distances to the fulcrum. Some authors [van Waes and Stocklli, 2002] suggested that these teeth are usually restored. Because it has been reported that tooth fractures will commonly occur along the fissures [Needleman and Wolfman, 1976]. Thus, these eccentric contacts expose these teeth to significant occlusal trauma [Swepston and Miller, 1986].



In permanent teeth, two characteristic patterns of crack formations exist [Cameron, 1964]. They are centrally placed cracks and more peripherally directed cracks. While pressure is applied to the crown, these cracks widen and allow the movement of fluid inside the dentinal tubules [Morisaki et al., 1989] which may further increase the dentine sensitivity.

When vertical fracture occurs or the fracture extends through the pulpal floor or below the level of the alveolar bone, the prognosis is poor and the tooth should be extracted. [Clark and Caughman, 1984]. Regarding the treatment of crownroot fractures in primary teeth, the extraction of the involved teeth is generally chosen [Needleman and Wolfman, 1976; Morisaki et al., 1989; Andreassen and Andreassen, 1994]. According to literature, natural teeth are the ideal space maintainers [Duggal et al., 1995]. In addition parents were willing to save the teeth. Thus, in the present case, even though the fracture had a subgingival margin, pulpectomy was carried out followed by restoration with a preformed metal crown, rather than extraction.

The rubber dam clamp was used to stabilise the fragment, thus providing the perfect apposition. It is an excellent way to hold the pieces together. Moreover, it also provided advantages such as comfortable working ambiance without tongue interference. Glass ionomer was placed in the floor of pulp chamber and was utilised as a splinting material. As it was placed above the alveolar bone level, it will not interfere with the process of resorption.

Preformed metal crowns are considered as prerequisite after any pulp therapy in the primary dentition [Mink and Hill, 1971]. In the present case the mesial margin was left untrimmed and extended subgingivally, to cover any subgingival caries, here it was modified in order to envelop the fracture line, thus avoiding any possible microleakage.

Periodic review is important for the possible effects on the succeeding permanent tooth. Kennedy [1979] reported necrosis of pulp tissue in a primary molar due to indirect trauma to the chin. Holan [1997] presented an unusual pattern of resorption attributed to a traumatic injury to the chin. Though Andreasen stated that trauma to the primary dentition is usually confined to the supporting structures [Andreassen and Andreassen, 1994] Holan contradicted that it may apply to the primary incisors and not molars [Holan, 1997]. However, multiple roots and greater root surface reduce the possibility of severe damage to the periodontal ligament when compared with incisors. Therefore, 3 month periodic review interval was established. Intraradicular resorption of calcium hydroxide and iodoform has been reported in primary teeth [Nurko et al., 2000] and demonstrated that the samples collected from the resorbed canals were free of bacterial contamination.


This case highlights the need for a systematic history and examination in all cases of dental trauma. The possibility of more than one injury should always be investigated. Where the chin has been involved, particular attention must be paid to the mandible, predominantly the posterior primary teeth. This case also emphasises that not all primary teeth with crown-root fractures need to be extracted and conservative management is possible. An interdisciplinary team should attend such cases and the examinations should be very careful to accomplish a prompt diagnosis and positive prognosis.


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V.S. Hariharan *, R. Rayen **

* Department of Paedodontics and Preventive Dentistry, Sree Balaji Dental College and Hospital. Chennai. Tamilnadu, India.

** Kidznteenz Healthcare Pvt Ltd, Exclusive Pediatric Dental Care Centre, Chennai, India.

Postal address: Dr V.S. Hariharan, Department of Paedodontics and Preventive Dentistry, Sree Balaji Dental College and Hospital, Chennai, Tamilnadu, India.

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Author:Hariharan, V.S.; Rayen, R.
Publication:European Archives of Paediatric Dentistry
Article Type:Clinical report
Geographic Code:9INDI
Date:Aug 1, 2012
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