Mandibular second premolars rank highest as the most common congenitally missing tooth, followed by the maxillary lateral incisor, excluding the third molars. In cases where the mandibular second premolars are missing and the primary second molars are present, it is often possible to maintain the latter for long term. If they are submerged due to ankylosis, they can be restored to the functional occlusal plane with restorations such as occlusal composites. If the adjacent teeth have drifted and tipped over the occlusal level of the primary molar, orthodontic treatment repositioning those teeth with subsequent restorative care may be necessary.

During orthodontic treatment, the size of the deciduous molar often needs to be reduced at interproximal surfaces to obtain optimal occlusion. Reduction of mesiodistal dimensions of a deciduous tooth is required to match with the succedaneous tooth of smaller dimensions ( Fig. 89.2 ). In skeletally immature patients, ankylosed teeth may have to be extracted to avoid the restriction leading to a vertical growth of the alveolus. In such cases, careful space management is necessary for future treatment options.

Management of a submerged deciduous molar associated with a missing mandibular second premolar.

(A and B) Photographs showing the occlusal and the left buccal view of a patient with retained and submerged mandibular left primary molar. Note the lateral open bite. (C) View of the left buccal occlusion after orthodontic treatment. Note the reduction in mesiodistal width of the primary molar. (D) Restored primary molar using an onlay.

Patients with a congenitally missing lateral incisor seek treatment in the dental office at a relatively young age. The spacing associated with the maxillary anterior aesthetic zone is often a serious concern for the parents ( Fig. 89.3 ). These cases may often have maxillary canines erupting in the space for the maxillary lateral incisors. Occasionally, canine impactions may also occur. The presence of the lateral incisor is a guide to the direction of eruption for the permanent canines. Impactions and ectopic eruptions of the canine may occur due to a lack of eruption guidance. ^,

A case of a congenitally missing bilateral maxillary lateral incisors.

(A) Frontal view of the dentition. (B) Panoramic radiograph. Note the mesially erupting permanent canines in the position of the maxillary lateral incisors.

Two common treatment options for the treatment of congenitally missing lateral incisors include:

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  Space opening for restorative replacement of the missing lateral incisor

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  Space closure

• Orthodontic space closure: The choice of treatment depends upon the occlusion of the patient, patient profile and the remaining general growth of the patient. If the canine is to be substituted for the lateral incisor, it is reshaped for aesthetics. It may require slight extrusion in order to bring the gingival margin incisal to that of the central incisor. This helps establish an ideal gingival aesthetic relationship between the central incisor and the canine in the lateral incisor site. This is especially important for a patient with a high smile line. Often, the shade of the canine is much darker than the adjacent incisors. If so, it may have to be either bleached or veneered to match the shade with central incisors.

• Space maintenance and rehabilitation : If a decision to open space for the missing lateral incisor is made and the canine is unerupted, the canine is facilitated to erupt mesially into the lateral incisor spot to develop the alveolar bone with tooth eruption. Once the canine has erupted, the orthodontist can distalise the canine into a class I relationship with the opposing canine. The alveolar bone that develops in this manner can often be maintained during the growth years until definitive restorative care is feasible. The decision regarding space requirement for the subsequent replacement of the lateral incisor is made by the dentist. The ideal restoration for missing teeth is an implant. Before removing orthodontic appliances, the restorative dentist should review the progress of the treatment to confirm that adequate space for the prosthesis has been created. Space should be evaluated between the roots and at the level of the crowns to ensure successful implant placement. The root uprighting in the region of the missing tooth can be monitored with a periapical radiograph using the long cone technique. The implant is placed when the vertical growth of the patient is complete. This is usually around 14–15 years of age in girls and 16–17 years of age in boys. The changes in growth can be monitored by taking serial cephalometric radiographs at least a year apart. They serve as a reliable guide to evaluate the progress and determine the appropriate stage for implant placement. A Maryland bridge or a pontic on a retainer can serve as an interim prosthesis until the completion of growth.

Dental caries, periodontal disease and trauma are the most common causes of tooth loss. Sometimes, treatment is not sought for these lost teeth by the patients for extended periods of time. This lack of restorative care alters the equilibrium of the dentition. It leads to shifting and tipping of the individual dental units, changes the cant of the occlusal plane and creates functional shifts. It is possible to treat these situations by restorative means alone; however, it is not ideal. Tipped teeth can be included in the prosthesis design, such as telescopic crowns, a ring clasp or a reverse action clasp for a removable partial prosthesis, endodontic treatments and crowns for supra-erupted teeth. The tipped teeth, however, are not the best abutments for either a fixed or a removable prosthesis because the occlusal forces are not directed along the long axis of the tipped teeth. Besides, they often have three-walled periodontal bony defects on the side of the tip. ^, Orthodontic biomechanics is employed to intrude supra-erupted teeth and re-establish the correct occlusal plane. Such procedures may simplify the restorative treatment.

The current standard of care involves orthodontic treatment along with restorative treatment. The correct axial inclination of tipped teeth are established by orthodontics ( Fig. 89.4 ). This improves the periodontal prognosis and long-term maintenance of the teeth. It also improves access for the restorative dentist to idealise the subsequent fixed or removable prosthesis. It ensures the achievement of ideal interproximal embrasure form.

Space management in an adult with a mutilated buccal occlusion.

(A) Pre-treatment intraoral photographs of a patient with a mutilated dentition showing deep bite, missing mandibular left second premolar and first molar, and space between the mandibular right first and second premolars. The lingual occlusal view shows a congenitally missing mandibular incisor. (B) Post-treatment photographs show an uprighted mandibular left second molar, improved anterior overbite and space gained.

Sometimes, orthodontic space closure can eliminate the need for restorative care. An example of this is the frequently missing first permanent molar that was lost early in life, and the second molar erupted mesially tipped into the space of the permanent first molar. The ultimate possibility of closing the space with orthodontic mechanics depends on the general occlusion, crowding and available anchorage.

One of the most common malformations observed is the peg-shaped maxillary lateral incisor ( Fig. 89.5 A). The patient often presents with aesthetic discrepancies in the anterior region, including uneven space distribution and a midline deviation. The size and shape of the malformed tooth need restorative care, but prior to any restorative care, space distribution must be established. If sufficient space exists, a composite restoration or a ceramic veneer may be done to establish ideal results. However, in most patients, both the space distribution and occlusion are not ideal for restorative treatment. Space must be matched to the size of the contralateral incisor. The bite also must be corrected to normal overbite and overjet by orthodontic means ( Fig. 89.5 B). Adult cases with spacing in the upper anterior region treated with fixed orthodontic appliance followed by restorative treatment are shown in Fig. 89.6 .

Orthodontic and restorative management of peg-shaped maxillary lateral incisors.

(A) Pre-treatment intraoral photographs of a patient showing peg-shaped and malformed incisors. (B) Orthodontically aligned dentition with composite veneers on maxillary anterior teeth.

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