Nicole Winitsky1,2,*; Aron Naimi-Akbar3; Robert Nedelcu4; Torsten Jemt5,6; Jan-Ivan Smedberg7,8

1Department of Prosthetic Dentistry, Folktandvården Stockholm AB, Folktandvården Eastmaninstitutet; 2Division of Prosthetic Dentistry, Department of Dental Medicine, Karolinska Institutet, Stockholm; 3Health Technology Assessment-Odontology (HTA-O), Malmö University, Malmö; 4Department of Surgical Sciences, Plastic and Oral and Maxillofacial Surgery, Uppsala University, Uppsala; 5Department of Prosthetic Dentistry/Dental Material Science, Institute of Odontology, Sahlgrenska Academy at Gothenburg University; 6Brånemark Clinic, Public Dental Health Service, Region of Västra Götaland, Göteborg; 7Department of Prosthetic Dentistry, Folktandvården Eastmaninstitutet, Folktandvården Stockholms län AB; 8Department of Prosthetic Dentistry/Dental Material Science, Karolinska Institutet, Stockholm, Sweden

Background: In light of the large and increasing number of single implants inserted globally, surprisingly few studies have focused on the long-term (i.e., > 15 years) outcome of such treatment. Single anterior implants are predominantly placed in young patients with long remaining lifetime and infraposition in relationship to adjacent teeth has been observed in both younger and older patients. The treatment modality requires more knowledge regarding long-term positional changes and esthetic outcome.

Aim/Hypothesis: To report three-dimensional (3-D) movement of teeth adjacent to single implants in the anterior maxilla and to explore and estimate the potential associations with patient-related variables as well as to objective and subjective esthetic evaluation.

Material and Methods: 3-D movements of teeth adjacent to single anterior maxillary implant crowns were measured after 14 to 20 years in function. Dental casts from baseline (crown delivery) and follow-up examination from 30 patients, with a mean age of 21 years, were digitalized and aligned using a software program. The vertical (incisal) movements were related to patient and implant characteristics such as facial type, lower anterior facial height (LAFH), age at crown delivery, sex, the position of the implant, implant occlusion, cause of tooth loss, follow-up period, orthodontic treatment prior to implant placement and marginal bone level changes. The esthetic outcome was assessed using Visual Analogue Scale (VAS) and California Dental Association index (CDA). Correlation between tooth movements in 3-D (incisal, mesio-distal and bucco-palatal) as well as possible agreement between the VAS ratings of the clinicians and the patients were evaluated.

Results: The average rate of incisal tooth movement was 0.05 mm/year. 3-D movements of teeth adjacent to the implant crowns ranged from 0.2 to 2.3 mm during follow-up. Movements in an incisal and palatal direction were most pronounced and found to be correlated. Teeth adjacent to implants in the central incisor position exhibited a mean incisal movement of 0.5 ± 0.3 mm, while teeth adjacent to implants in lateral incisor or canine position each exhibited a mean incisal movement of 1.0 ± 0.5 mm. “Implants in central incisor position” and “implants in occlusion” were significantly associated with less incisal adjacent tooth movements. Incisal tooth movements of > 1 mm (30 %) were significantly associated with LAFH ≥ 70 mm. The esthetic VAS ratings associated poorly between patients (mean rating 85%) and clinicians (mean rating 67%) with Kappa index of 0.09 (“low agreement”). The CDA rating was assessed as satisfactory in 87% of the patients.

Conclusion and Clinical implications: Although infraposition occurs, patients are highly satisfied with and rates the esthetics of their implants higher than dentists. Risk assessment for infraposition may in the future focus more on individual patient related predictors than age at implant placement. It seems appropriate to always inform the patients, prior to treatment, about the possible need for replacement of implant crowns due to implant infraposition. This is yet another reason to perform screw retained implant crowns.

Disclosure of Interest: N. Winitsky Conflict with: Nobel Biocare, Conflict with: Nobel Biocare, Conflict with: Nobel Biocare, A. Naimi-Akbar: None Declared, R. Nedelcu Conflict with: Nobel Biocare, Conflict with: Nobel Biocare, Conflict with: Nobel Biocare, T. Jemt Conflict with: Nobel Biocare, Conflict with: Nobel Biocare, Conflict with: Nobel Biocare, J.-I. Smedberg: None Declared

Keywords: aesthetic zone