Dentists are faced with a challenging clinical situation when a young adolescent patient presents with one or several congenitally missing permanent teeth. The treatment plan that is developed for a young patient must be relevant for many years in the future. Today’s patients have different restorative needs than what was seen in the past because they have either a low caries rate or are caries-free. For this reason, there is very rarely a need for full-coverage, fixed prosthodontic restorations. Instead, the replacement of a missing tooth or teeth is with implants, followed by fabrication of a crown. Despite the increased expense, parents are choosing the implant option versus other restorative options that are available. Needless to say, successful treatment requires cooperation between the orthodontist, the implant surgeon, and the restorative dentist.
ORTHODONTIC MOVEMENT OF THE CUSPID TO ENHANCE RIDGE AUGMENTATION
Figure 1. The maxillary right cuspid in the position of the maxillary right lateral incisor, anterior view.
Figure 2. Patient in Figure 1, lateral view.
When a patient with early mixed dentition presents with a congenitally missing lateral incisor, careful consideration must be given to when the primary cuspid should be extracted without compromising the thickness of the alveolar ridge. If the permanent cuspid erupts immediately distal to the permanent maxillary central incisor (Figures 1 and 2), the primary lateral incisor and/or primary cuspid should be extracted just before moving the permanent cuspid distally.3 The distal movement of the cuspid, known as orthodontic implant site development, will help develop the alveolar ridge in the area of the lateral incisor. The distalization of the cuspid results in the development of a dense alveolar ridge along the fiber tracks of the periodontal membrane.4 With this movement there is significantly less alveolar bone loss than if the tooth is extracted.5 By appropriate orthodontic movement of the cuspid in this fashion, the need for a surgical ridge augmentation is generally eliminated. The resultant bone height and thickness should allow for ideal implant placement.
SPACE MAINTENANCE DURING ORTHODONTIC TREATMENT
|Figure 3. Replacement of congenitally missing lateral incisors with prosthetic teeth during orthodontic treatment.||
Figure 4. Patient in Figure 3, occlusal view.
|Figure 5. The mandibular left second primary molar acting as a space maintainer until implant placement for the congenitally missing permanent second bicuspid.||
Figure 6. Panoramic radiograph of the patient in Figure 5.
It can be difficult for children and adolescents to undergo orthodontic treatment, and even more so when the patient is missing a maxillary anterior tooth. Once the appropriate space for the replacement of the missing tooth is accomplished there is the need to retain that space. Routinely, an impression is made of the maxilla and mandible, and the models are sent to the orthodontic laboratory along with an appropriate tooth shade. The laboratory then fabricates a prosthetic tooth to fit the space, and an orthodontic bracket is added on the labial surface. The prosthetic tooth is attached to the maxillary archwire, and the necessary adjustments are made in order to avoid impinging on the ridge or proximal gingival tissues. By performing this minor addition, the aesthetics improves markedly, and generally the patient cooperates with treatment (Figures 3 and 4).
AFTER ACTIVE ORTHODONTIC TREATMENT
Usually, orthodontic therapy will be completed before facial growth is completed. The question then is how to maintain the space until the patient is ready for implant placement. If there is a short period between the completion of active orthodontic treatment and implant placement, a removable Hawley retainer with a prosthetic tooth attached to it will be adequate. This appliance can be used after implant placement and during the healing phase.3 The removable appliance must rest passively on the ridge to avoid impinging and thus irritating the soft tissue.
Figure 7. A resin-bonded bridge replacing the maxillary right lateral incisor. Orthodontic treatment is completed. The restoration will remain until facial growth is completed and an implant is placed.
Figure 8. Panoramic radiograph of the patient in Figure 7. The ridge in the edentulous area (maxillary right lateral incisor) is well developed after orthodontic therapy.
If there is a long period of time between the removal of the orthodontic appliances and the placement of the implant, a more permanent retainer is required. Individuals in this age group cannot be depended upon to wear a removable appliance for an extended period of time. In addition, the removable appliance will deteriorate over time and will not be as aesthetically pleasing as a fixed bonded retainer. Therefore, in most cases, the patient is referred back to the restorative dentist for the fabrication of a resin-bonded bridge to hold the tooth position and maintain the space until facial growth is completed and the time for implant placement is reached (Figures 7 and 8).
DETERMINING THE COMPLETION OF FACIAL GROWTH
|Figure 9. Patient in Figures 5 and 6. Superimposed cephalometric tracings demonstrating no change in vertical growth from 7/9/99 (black) to 6/6/00 (red). An implant can now be sucessfully placed.|
Since the most ideal time to place the implant is when growth of the maxilla and mandible is completed, it is important to determine when this has occurred. In the past, the hand wrist film was used to make this determination. Nevertheless, this measure varies from patient to patient.3 Most boys will not complete facial growth until their late teens, but for girls facial growth is generally complete by the age of 15. An alternate measure is required. Consequently, the most accurate method of evaluating the completion of an individual’s facial growth is by superimposing consecutive cephalogramic radiographs taken at 6-month intervals. The most recent cephalogram is superimposed over the prior one. The cephalograms are superimposed using Sella—Nasion as the reference, since this is stable early in development. The anterior cranial base is fused at approximately 4 to 5 years of age, making it an excellent reference plane. If facial growth is complete, when the sequential radiographs are superimposed, the vertical relationship (Nasion-Menton) will not have changed. If there is a change in the vertical facial height another cephalogram should be exposed in 6 months and a similar analysis performed.
With the completion of facial growth, the implant can be safely placed without concern for any additional eruption of the adjacent teeth. This will allow an excellent aesthetic result (Figure 9).
The development of osseointegrated implants has given the dental profession the opportunity to provide young patients with the most conservative aesthetic result when replacing congenitally missing teeth. This treatment requires the collaboration of the restorative dentist, implant surgeon, and orthodontist. The ultimate determining factor for success in these cases relies upon an understanding of facial growth.
- Rupp R, Dillehay J, Squire C. Orthodontics, prosthodontics, and periodontics: a multidisciplinary approach. Gen Dent. 1997;45:286-289.
- Balshi TJ. Osseointegration and orthodontics: modern treatment for congenitally missing teeth. Int J Periodontics Restorative Dent.1993;13:494-505.
- Spear F, Mathews D, Kokich,V. Interdisciplinary management of single-tooth implants. Seminars in Orthodontics. 1997;3:45-72.
- Fowler PV. Long-term treatment planning for single tooth implants: an orthodontic perspective. Ann R Australas Coll Dent Surg. 2000;15:120-121.
- Richardson G, Russell KA. Congenitally missing maxillary lateral incisors and orthodontic treatment considerations for the single-tooth implant. J Can Dent Asso. 2001;67:25-28.
Dr. Gostovich received her dental degree from the University of Medicine & Dentistry of New Jersey in 2001. She is currently a second year orthodontic resident at the University of Pennsylvania. She will complete her postgraduate orthodontic training in 2003.
Ms. Johnston is currently a third year dental student at the University of Pennsylvania.