Key points

Introduction

Dentoalveolar injuries are an important and common component of craniomaxillofacial trauma. The dentition serves as a vertical buttress of the face and fractures to this area may result in malalignment of facial subunits. Furthermore, the dentition is succedaneous with 3 phases—primary dentition, mixed dentition, and permanent dentition—mandating different treatment protocols. This article is written for nondental providers to diagnose and treat dentoalveolar injuries.

Introduction

Dentoalveolar injuries are an important and common component of craniomaxillofacial trauma. The dentition serves as a vertical buttress of the face and fractures to this area may result in malalignment of facial subunits. Furthermore, the dentition is succedaneous with 3 phases—primary dentition, mixed dentition, and permanent dentition—mandating different treatment protocols. This article is written for nondental providers to diagnose and treat dentoalveolar injuries.

Anatomy

The primary dentition and permanent dentition are housed within the alveolar bone of the maxilla and mandible ( Fig. 1 ). The quantity of alveolar bone is dependent on the presence and health of teeth as forces are transmitted through the surrounding periodontal ligament (PDL). Basal bone comprises the remainder the maxilla and mandible.

Basic dental anatomy.

Blood supply to mandibular alveolus is mainly from the terminal branches of the internal maxillary artery with contributions from the branches of the facial and lingual arteries. The maxillary alveolus receives its vascular supply from the internal maxillary, ascending pharyngeal, and lingual tonsillar twig arteries. As inferred from the studies by Bell, the redundant nature of the vascular supply allows most dentoalveolar bony injuries to heal well despite mucosal lacerations and extensive comminution. Vascular supply must be considered, however, in incision design when significant trauma is present.

The dentition is innervated by the third division of the trigeminal nerve. The posterior trunk of the mandibular nerve gives rise to the inferior alveolar nerve that enters the mandibular foramen and continues in the inferior alveolar canal. This nerve splits at the mental foramen where a portion exits to innervate the lip and mandibular labial mucosa, and a portion continues on as the incisive branch to innervate the mandibular incisors. The mandibular teeth and their PDLs receive their vascular supply and innervation by way of nutrient canals from this inferior alveolar canal. The lingual, long buccal, and mylohyoid nerves also contribute to innervation of the mandibular dentition and alveolus. The maxillary teeth are innervated by the maxillary nerve by way of the posterior superior alveolar, middle superior alveolar, and anterior superior alveolar nerves. The palatal alveolus receives innervation from the greater and lesser palatine nerves as well as from the terminal branches of the nasopalatine nerve. Accessory and anatomic variations are common.

Teeth are divided into a crown and a root. The crown consists of an outer shell of enamel over dentin that is replete with tubules that connect to the innermost pulp tissues. The pulp tissue contains blood vessels, nerves, and stem cells and may become calcified with trauma or infectious insult. The roots consist of the same basic layers; however, cementum with Sharpey fibers that connect directly to bone replaces the enamel. In addition, there are numerous accessory canals that travel from the root pulp to the PDL to create a complex network of dental vascular supply and innervation. As tooth roots continue to develop, they lengthen and change from an open or immature apex to a closed or mature apex.

The PDL surrounding teeth consist of 9 groups of collagenous fibers that transmit the forces of mastication to the surrounding bone and gingival soft tissue. Radiographically, teeth sit in a socket lined with cortical bone referred to as the lamina dura. The bone on the buccal and lingual aspects of the roots are referred to as the buccal and lingual plates. Normal healthy gingival tissue consists of a band of keratinized tissue near the crowns of teeth and loose alveolar mucosa covering the remainder of the alveolus.

The primary dentition begins erupting between 6 and 12 months of age and results in 20 teeth with spacing that is normal and desirable. The permanent dentition commences with the eruption of the 6-year first molars and continues into the late teenage years and 20s as the third molars complete formation for a total of 32 teeth. The mixed dentition stage represents a transition between the primary dentition and permanent dentition and may result in unstable occlusal schemes. Understanding this basic dental anatomy is important in the diagnosis, treatment options, and prognosis associated with dentoalveolar injuries.

Based on anatomy, dentoalveolar injuries may be divided into several categories. First, injuries to the primary dentition and permanent dentition are treated in a different manner. Second, the extent of tooth structure injured must be evaluated in conjunction with amount of root development. Last, the degree of involvement of the alveolar bone must be considered, with a greater extent requiring principles more akin to fracture treatment.

Injury to the primary dentition

Dental trauma, especially in children, can be a challenging experience for any practitioner from a patient management standpoint. An attempt is made to break this complex issue down into a systematic approach to simplify and improve patient outcomes, written with the intent of being a useful guide to practical treatment in hospital-based emergency settings.

For the sake of this discussion, children are defined as anyone possessing succedaneous teeth or in the primary dentition who is not an adult with retained primary teeth. Complete exfoliation of the primary dentition generally is complete at approximately age 12. As discussed previously, the maturation of a child’s permanent dentition and root development greatly affect treatment outcomes. The various functions of primary teeth include

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  Space maintenance for permanent tooth eruption

  
  
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  Alignment and spacing of the permanent dentition

  
  
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  Occlusion

  
  
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  Phonetics

  
  
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  Self-esteem

  
  
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  Nutritional intake/diet

If the developing permanent teeth are jeopardized by forceful movement of primary teeth in the alveolus, however, preservation of the primary dentition is secondary.

The primary dentition, with 20 teeth in total, are named in the United States starting from the maxillary rightmost posterior secondary primary molar as A around the arch to maxillary left secondary molar as J , with the mandibular left secondary molar commencing with K and continuing through the alphabet to T at the mandibular right secondary molar. In general, eruption ( Fig. 2 ) begins at 6 months in anterior mandible and is complete at 30 months with the eruption of the primary secondary molars. A rule of 4 teeth erupting every 7 months can be used to evaluate and assess sequence. A child then progresses until approximately age 5 with minimal changes apparent intraorally until the first permanent molars erupt posterior to the secondary primary molars. The anterior dentition transitions at approximately age 8 to 9 years with completion of exfoliation of the primary dentition at approximately age 12. In general, the entire permanent dentition has erupted by age 18 to 21 years, including the third molars.

Primary dentition and permanent dentition eruption sequence (acknowledgment: Partners in dental care).

Tooth eruption

Of considerable importance, permanent tooth buds/permanent dentition form in alveolus close to the tongue or lingually and erupt generally into the pediatric root structure (laterally) and resorb it slowly until exfoliation occurs or the tooth erupts adjacent to the primary tooth with no exfoliation. This lends to the primary goal of treatment of dentoalveolar trauma in the primary dentition, which is to avoid injury or insult to the developing permanent tooth and to avoid precipitation of significant malocclusion from management of dentoalveolar trauma.

Incidence of traumatic injuries in children

Children exhibit a bimodal distribution in trauma to the oral cavity, with falls the primary mechanism of injury occurring when a child is beginning to become mobile. According to Andreasen and colleagues, a second peak occurs at age 8 to 10 years with a 2:1 male-to-female ratio as sports become more physical. Child abuse is, unfortunately, another significant cause. In a 2000 review of 879,000 documented US child abuse cases, 19.3% were physical abuse, with 50% of these involving trauma to the head and/or neck. Internationally, approximately 7% of all childhood injuries involve the oral cavity. Concern should arise when the accident and narrative of the accident do not correlate well.

Injury classification schemes

Many dentoalveolar trauma classification systems have been developed ( Figs. 3–6 ). It is useful to discuss and use them for communication with other health care providers and in documentation of the nature and extent of the injury for medicolegal reasons. Two of the most common classification schemes are discussed, Ellis/Davey and Andreasen.

Infraction ( A ), uncomplicated enamel limited fracture ( B ), uncomplicated crown fracture ( C ), complicated crown fracture ( D ), uncomplicated crown-root fracture ( E ), complicated crown-root fracture ( F ), and root fracture ( G ).

Injuries to the PDL and alveolar supporting structures.

Patterns of alveolar fracture.

Ellis/Davey classification.