Editor’s intro: When treatment planning patients with peg-shaped maxillary incisors, Drs. Donald Rinchuse and Dara Rinchuse offer some perspective based on each patient’s unique circumstances.
Drs. Donald J. Rinchuse and Dara L. Rinchuse discuss treatment for this tooth type for orthodontists in conjunction with the family’s treatment team
Based on the meta-analysis by Hua, et al., in 2013,1 the prevalence of peg-shaped maxillary permanent lateral incisors (Figures 1A, 1B, 1C, and 2) varies by race, population type, and gender. Overall, the prevalence of peg-shaped maxillary permanent lateral incisors is 1.8%. It is highest in the Mongoloid (3.4%) race. The prevalence in an orthodontic population is 2.7%. Women are 1.35 times more likely than men to have peg-shaped maxillary lateral incisors. Although the prevalence is the same for unilateral and bilateral peg-shaped lateral incisors, the left side is twice as common as the right side.1
The dilemma for the orthodontist (and family dentist) is what to do in cases with peg-shaped maxillary permanent lateral incisors (i.e., extract, enlarge, keep the same size and shape, etc.), which is a decision the orthodontist makes in consultation with the cosmetic dentist as well as the patient/family. These writers are not certain that the primary responsibility for making the decision on what to do for these teeth (i.e., restorative-wise) is that of the orthodontist alone; certainly, it is a team decision. Nonetheless, the orthodontist will have to make accommodations for what is decided in his/her orthodontic treatment.
There are several possibilities for these teeth, and there are several algorithms that can be used, but in most instances, the decision is made based on the unique circumstances with which each patient presents. One of the first considerations is whether or not to keep these teeth; certainly, at times it may be better for the patient if these teeth are extracted. The patient’s type of dental occlusion and facial pattern would be several of the considerations for deciding on extraction(s). For instance, if the patient has a Class III occlusion with an anterior crossbite, there would be more of a tendency to keep peg-shaped lateral incisors. On the other hand, if the patient has an Angle‘s Class II1 malocclusion with a severe overjet in need of upper arch extraction, it would make sense to consider extracting bilateral peg-shaped lateral incisors. When the occlusion is Class I, it is a more difficult decision on whether to extract peg-shaped lateral incisors. Another consideration would be whether there is unilateral or bilateral peg-shaped lateral incisors. If both laterals are peg-shaped, does this lead more so for the tendency to extract?
If the peg-shaped lateral incisor(s) is/are neither extracted nor enlarged (i.e., kept as they are), then they should be moved and positioned incisal/gingivally, so they are as long as the central incisors. They can also be extruded and made longer than the central incisors and then have the pointed incisal edge(s) “ground off.” The shorter these teeth are next to the central incisors, the more diminutive they will appear. So keep them “long.” This same concept is also true for small-sized lateral incisors (not truly peg-shaped) that will not be enlarged. Parenthetically, after a patient wears a maxillary vacuum-formed clear retainer for even a very short period of time, these lateral incisor teeth (that have been so diligently positioned at the height level of the central incisors) can move gingivally and get shorter. The reason for this occurrence is unclear. It should also be mentioned that when using fixed orthodontic appliances, peg-shaped maxillary lateral incisors can be bracketed with lower incisor brackets rather than regular-sized maxillary lateral incisor brackets.
If the decision is to “build” these teeth up (enlarge with bonding material or crown), then the question is, Should they be enlarged to a relatively normal size versus just enlarging them a minimal amount? Obviously, the esthetics will be better if these teeth are enlarged to a relatively normal size. However, peg-shaped laterals obviously have very small, slender roots, which are proportional in size to the small size of the crowns of these teeth. This presents some concerns. If these teeth crowns are enlarged to a normal size, the crowns of these teeth will be proportionally large compared with the roots. So you would now have a very large tooth crown supported by a small tooth root. This would present a liability for a child orthodontic patient possessing peg-shaped lateral incisor(s), who will have to deal with the consequences (i.e., stress and forces) of a large size crown on a small, slender root for many, many years to come.
The other aspect of having a large crown on a very small, slender root would be creating a ledge at the juncture of where the crown meets the root. This would present a periodontal/oral hygiene concern from food trapping in this junction area. Similar considerations are for enlarging retained deciduous maxillary incisor teeth when the permanent teeth are congenitally missing.
Beside the dilemma of peg-shaped maxillary incisors, orthodontists are often faced with many other issues when preparing for orthodontic treatment. To discover more about this subject, read Dr. Ricky Harrell’s “Tooth substitutions in orthodontic treatment”.
1. Hua F, He H, Ngan P, Bouzid W. Prevalence of peg-shaped maxillary permanent lateral incisors: A meta-analysis. Am J Orthod Dentofacial Orthop. 2013;144(1):97-109.