Once you notice that the primary lateral incisors aren’t present in a child, you can almost be sure that the permanent later incisor is not going to erupt either. This is a situation that has to be dealt with often. Third molars, lateral incisors, and lower second premolars are the most commonly missing teeth – with genetics being the biggest contributing factor. However, there are many systemic conditions such as ectodermal dysplasia, chondroectodermal dysplasia, achondroplasia, Rieger syndrome, incontinentia pigmentin, and Seckel syndrome, which can cause this too.
How Do We Treat The Missing Later Incisor?
Treatment options most often include:
- Space closure for canine substitution – restoring the canine to mimic the lateral incisor.
- Space opening/ space maintenance for prosthetic restorations.
When considering canine substitution, these are the factors to take into account:
- A balanced facial profile is preferred over convex profile – which is most often associated with a retrognathic mandible.
- The prominent root eminence of the canine, which can cause esthetic concern – especially with high smile lines.
- Ideally, the canine occlusion should be Angle II without lower anterior crowding or Angle Class I with/ without lower anterior crowding (which can be treated with mandibular extractions).
- To mimic the lateral incisor – the gingival margins of the canine should be slightly lower than the central incisors.
- Consider the color difference between the canine and central incisor, as it could be a deterrent for an ideally esthetic smile. Possible esthetic bonding of the canine maybe indicated.
When considering space gaining/ maintenance – these are the factors to take into account:
- First determine how much space you’re working with by making a diagnostic wax-up and using the Bolton analysis.
- Use the golden proportions – adjacent incisors need to have a ratio of 1:0.618 when looking directly from the anterior.
After the space is analyzed, the types of prosthetic restorations can be determined – the options are:
- Resin-bonded fixed partial dentures – a highly conservative treatment option.
- Cantilevered fixed partial dentures -second most conservative option – and has the advantage of using the canine (due to its length of root and crown features) as its abutment for a cantilevered restoration.
- If a significant amount of the facial structure of the canine (because of esthetics or caries) needs to be altered, then a full coverage preparation for the cantilever is preferred.
- Full coverage bridge restoration spanning from the central incisor to the canine. This is the least conservative treatment option. The possible discrepancy of the esthetics between the restored and the unrestored central incisor should be especially considered.
Implant placement:
- Consider the alveolar ridge width – if sufficient bone width is not present, a bone graft should be placed either prior to or simultaneously with the implant placement.
- For developing the papillae – 1.5 to 2.0 mm of space is recommended between the head of the implant and the cementoenamel junctions of the adjacent teeth.
- If the available edentulous space for replacing the lateral incisor is 7 mm wide or greater, a traditional implant diameter of 3.5mm to 3.75 mm can be placed. The minimum inter-radicular distance that is required is 5 mm. Narrow diameter implants can be considered with limited inter-radicular space.
- The ideal time for implant placement is when the facial growth of the patient is complete – as determined by hand wrist radiographs.
Survival Rates of Prosthodontic Treatment Options
| Dental Tx Option | 5 Year Survival Rate | 10 Year Survival Rate |
| Resin Bonded Bridge | 83.6% | 64.9% |
| Fixed Partial Denture | 93.8% | 89.2% |
| Implant Supported Crown | 94.5% | 89.4% |