Quality Resource Guide l Making Pediatric Dentistry Part of General Practice 7th Edition 5 www.metdental.com Sealants should be placed as soon as feasible in children who are at risk of caries. While most published data on the effectiveness of sealants refer to their use on permanent teeth, sealants on primary teeth also have shown value. There is sufficient need to seal primary molars as epidemiologic studies have shown that over 80% of caries in preschool children are found on the pit and fissure surfaces of primary molars. Growth and Development It is important for those practitioners who see children to know when teeth first start to develop and when they erupt. Not only is this a frequent question that parents ask, but also it is critical to understand developmental problems of teeth. Table 5 gives estimates of mineralization and eruption of primary and permanent teeth. However, it should be recognized that these average values might vary greatly between children. Normal Spacing Development Most primary dentitions have generalized spacing, and frequently there are diastemas occurring between the mandibular primary canine and first primary molar, and between the maxillary lateral primary incisor and the maxillary primary canine, often referred to as primate spaces. The first permanent molars ordinarily erupt in an end-to- end relationship, but may also erupt into a Class I relationship (the mesial buccal cusp of the maxillary first permanent molar interdigitates in the buccal groove of the mandibular first molar), or a Class II relationship. If the mandibular arch contains primate spaces, the erupting first permanent molar may cause the second primary molar and the first primary molar to move forward, closing the primate space, and allowing the permanent molars to shift forward into Class I relationship. This sometimes is referred to as the first shift, which can occur between ages 6-8. With the exfoliation of the primary molars and their replacement with the premolars, the first permanent molars may undergo another shift, the second shift or Leeway Shift. This shift is due to the larger size of the primary molars compared to the succeeding premolars. The average leeway space (per side) of 1.7 mm exists in the mandible, and 0.9 mm in the maxilla. Therefore, permanent molars that are in end-to- end relationship in the mixed dentition can also shift to Class I relationship with the transition to the full permanent dentition. Incisor Position With the eruption of the lower permanent incisors, a 2.2 to 2.5 mm widening of the arches between the canines may occur, due to growth or to the distal migration of the primary canines. Other factors that allow the larger permanent teeth to erupt into the space occupied by the smaller primary incisors is the forward positioning and the angulation of the permanent incisors, as well as utilization of diastemas, if present in the primary incisor region. In general, the average child has some spacing in the primary incisor region, whereas, in the permanent incisor region there is often some crowding, especially in the mandible. Another temporary developmental problem often exists during the eruption of the maxillary anterior segment, often called “the ugly ducking stage”. This is due to the maxillary permanent canines pressing on the developing roots of the lateral incisors, pushing the roots mesially and causing the crowns of the central and lateral incisors flare distally. With further eruption of the canines, the lateral incisors are pushed mesially, properly aligning the incisor crowns and closing of the diastema between the centrals. Space Maintenance Space maintainers are often indicated for the premature loss of primary molars due to dental caries. The early loss of second primary molars is especially critical because the first permanent molar will drift forward causing a shortage of the space needed for the premolars to erupt. This mesial shift of the first permanent molars most often will lead to a major crowding problem, often with blocked out premolars. However, if the premolar under the primary tooth that is to be extracted will soon erupt, indicated by no bone over the crown of the erupting tooth or the root of the premolar is at least half formed, space maintenance is not indicated. The practitioner should recognize that space loss can occur very rapidly after tooth extraction. Consequently, space maintenance appliances should be placed as soon as possible, or the patient should be referred as soon as possible to a dentist who is comfortable with constructing the appliances. Restorative Care Two important principles for restorative care in children are having good local anesthesia and having good isolation on teeth that are being restored. There is no doubt that a child is a much better patient when they do not have pain during a procedure, when they do not have to deal with water in the back of their mouths, and when they do not experience tastes and objects that are part of restorative care. Furthermore, a rubber dam retracts soft tissues, provides contrast, reduces salivary contamination and protects the airway. Although amalgam and composite are both good restorative materials for intracoronal restorations in children, there is a trend toward greater use of composites. Such a change is the result of better composite materials, patient preference and the political issues regarding mercury disposal. Disadvantages of composite materials, however, include the need for more rigorous techniques, requirement for absolute moisture control (especially for Class II restorations) and greater cost. Preformed crowns are often indicated in the restoration of primary teeth that have large lesions with cusps in jeopardy. Additionally, crowns are generally indicated for teeth that have had pulp treatment or teeth with one or more interproximal lesions. The restoration of teeth with preformed crowns can be challenging, especially if two adjoining teeth need crowns, or if there is space loss due to advanced caries. It is often prudent to