A study by Hvaring and colleagues has looked at the outcomes for patients with hypodontia and more specifically the treatment for missing teeth. They looked at a cohort of 50 patients with 6 missing teeth or more with a mean age of 26. These patients were examined clinically assessing mucosal discolouration, crown morphology, colour, and papilla index.
Deciduous teeth showed good outcomes whereas implants had poorer results. Changes in gingiva colour was seen only for implants and occurred for all fixtures in the anterior mandible and the majority of those in the anterior maxilla. As you would expect papilla index scores were poorer for implants and conventional bridges when compared with orthodontic space closure.
A pubmed link to the paper is below
Implants are a popular treatment modality in the management of patients with hypodontia as they provide tooth replacement without the need for adjacent tooth support or retention. Over time those working in the hospital services have seen case from 5 years or more return with either mechanical or biological complications. Patients with hypodontia may have adequate bone stock around the top of the ridge but this becomes more compromised higher in the alveolus. Over time the alveolus is likely to continue to resorb as illustrated in the above research resulting in mucosal discolouration due to the slow exposure implant threads. In such patients, who have such underdeveloped ridges, alternative tried and tested treatments maybe wiser to consider. Resin bonded bridges are predictable, efficient with good long term outcome data. Consideration for the patients long term maintenance-especially if treated in late adolescents-needs to be a significant consideration.