Tooth movement adjacent to single anterior maxillary implants after 14-20 year follow-up

KXZXK ePOSTER CLINICAL RESEARCH – PERI-IMPLANT BIOLOGY

Background: Various levels of tooth movement adjacent to single-implant restorations have been observed in follow-up studies. However, few studies with more than 10-years of follow-up and few studies with three-dimensional measurements of tooth movement have been published. Uncertainty remains weather patient specific parameters may influence the magnitude of movement and little is known about perceived esthetics and status of anterior single implant crowns after more than 10 years in function.

Aim/Hypothesis: The aims of this study are, to report the degree of tooth movements adjacent to single implants in the anterior maxilla after 14-20 years in function and to relate the measurements to parameters which may influence tooth movements and to the patients′ and observers′ esthetic assessment.

Materials and Methods: A group of 42 patients (mean age 20.7 years) received 53 anterior maxillary single implants between 1996 and 1997. 3-D measurements of tooth movement were performed on scanned study casts from baseline and after 14 to 20 years in function. The scanned models were analyzed in a digital software program (Geomagic Control X). Linear photogrammetric analysis was used to measure Upper and Lower Anterior Facial Height (UAFH/LAFH) and to determine facial type (long, neutral, short). Esthetics and status of remaining original implant crowns were assessed with Visual Analogue Scale (VAS) and California Dental Association INDIAx (CDA). Uni- and multivariate analyzes with the parameters facial type, LAFH (more or less than 70 mm), age at implant placement, gender, implant position, occlusion, reason for tooth loss, follow up time, VAS (0-100) and CDA scores (R, S,T,V), were used to analyze the association with movement of adjacent teeth in relation to the anterior maxillary single implants.

Results: After 14 to 20 years, thirty patients with original single implant crowns were examined. The incisal edge of the adjacent tooth moved on an average 0.01 mm (SD:0.06, range -0.15-0.1) in distal, 0.8 mm (SD:0.5, range 0.1-2.2) in incisal and 0.3 mm (SD:0.8, range -2.2-2.3) in palatal directions. Implant crown infraposition of more than 1 mm at the incisal edge was found in ten patients. Patients with a LAFH exceeding 70 mm were associated with larger vertical tooth movements (more infraposition; P < 0.05). VAS-ratings of more than 80 were found in 90% of assessments by the patients but only in 20% by the dentist. A correlation was found between the VAS score and infraposition of central incisors (P < 0.05). No correlation was found between the degree of implant infraposition and; age, gender and time of follow-up. The CDA rating was assessed as satisfactory in 26 patients (87%).

Conclusions and Clinical Implications: The present study shows single implant crowns in the anterior maxilla with an infraposition exceeding one mm in one third of the patients, after 14-20 years in function. Further, patients with LAFH of more than 70 mm might be at greater risk of severe infraposition long-term. Satisfaction with the crowns is rated high despite infraposition and is higher among patients than dentists. The infraposition occurring slowly over time does not seem to be very noticeable to the patients.

Acknowledgements: The author acknowledges Dr Anastosios Grigoriadis, Lecturer, Specialist in Oral Prosthodontics, Dr Anna Andlin, Associate professor, Specialist in Orthodontics and Dr Aron Naimi-Akbar, Senior dental officer, Specialist in Oral and Maxillofacial surgery.

Keywords: Tooth movement, Infraposition, Facial shape, Long-term follow-up, Patient satisfaction