CLINICAL ORAL IMPLANTS RESEARCH

Single crowns supported by short (6 mm) dental implants in the posterior region: a 3-year prospective
study
G. Frainer Barbosa,

1 E. Aydos Villarinho,1 D. Fernandes Triches,1 F. Rizzo Alonso,1 L. Mezzomo,2 E. Rolim Teixeira,1 R. Sadami

Arai Shinkai1
1
Dental School, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto alegre, Brazil, 2

Dental School, Federal University

of Santa Catarina (UFSC), Florianopolis, Brazil
Background: Short dental implants have been considered as an alternative treatment to advanced bone augmentation surgery in
the posterior region of maxilla and mandible. Nevertheless, most previous studies clustered the clinical outcomes of short
implants supporting different types of reconstructions, from single crowns to fixed partial dentures and overdentures. Also, they
usually assessed survival rates of short implants based on heterogeneous data from both retrospective and prospective studies.
Therefore, there is still controversy on the prognosis and biomechanical risk factors for the rehabilitation of the posterior region
of maxilla and mandible with single crowns supported by short implants.
Aim/Hypothesis: This 3-year prospective clinical study aimed to assess the success and survival rates of the rehabilitation of the
posterior region of the maxilla and mandible with single crowns supported by short dental implants (6 mm). Additionally, this

study tested the association of prosthetic complications with implant location (maxillary premolar, mandibular premolar, maxil-
lary molar, mandibular molar), crown-to-implant ratio, occlusal area and crown volume.

Material and methods: A consecutive sample was composed by 20 patients (12 females and 8 males; age range between 25 and
76). Inclusion criteria were: (1) need for single implant in the posterior region of maxilla or mandible with bone height limitation
for long/regular implant placement; (2) recommendation for short 6 mm implant with a 2-mm-safety margin from the inferior

alveolar nerve or maxillary sinus floor, and (3) at least 6-mm-bone-thickness. Exclusion criteria were: (1) history of osseointegra-
tion failure; (2) presence of biomaterial or material graft; (3) presence of diabetes, smoking habits, imunosuppression, local radio-
therapy, active periodontal disease on remaining teeth, cystic or neoplastic lesions; (4) poor oral hygiene; (5) partial or complete

denture in the opposite arch. A total of 46 6-mm-short implants (Standard Plus Regular Neck SLActive, Straumann AG, Basel,
Switzerland) were placed on the posterior maxilla (n = 23) and mandible (n = 23). Metalloceramic single crowns were installed
3 months after implant placement. Clinical recall was scheduled every 6 months. Data collection included: presence/absence of

bruxism screening using a standardized questionnaire and the BiteStrip (SLP, Pulheim-Stommein, Germany) device; measure-
ment of crown-to-implant ratio, occlusal area and crown volume; any biological or prosthetic complication. Data were analyzed

by descriptive statistics, Chi-square tests and Student t-tests, at the 5% level of significance.
Results: After a 36-month follow-up, 2 implants were lost in mandible and none in the maxilla. The overall Survival Implant
Rate was 95.65% (100% for maxilla and 91.31% for mandible). The two lost implants occurred in the same patient, who
reported bruxism and had BiteStrip score = 3; oral hygiene was good. Six patients (10 crowns) had prosthetic complications: 1
fracture of the veneering material and 10 prosthetic screw loosening (8 in mandible and 2 in maxilla). Complication rate was

39.13% in mandible and 8.7% in maxilla. Three out of six patients, correponding to 6 crowns, had bruxism presence and Bite-
Strip score = 3. There was no significant difference of prosthetic complications in relation to anatomical region (maxillary pre-
molar, mandibular premolar, maxillary molar, mandibular molar) (P = 0.180). No significant difference of crown-to-implant ratio

(P = 0.359), occlusal area (P = 0.318) or crown volume (P = 0.173) was found between crowns with or without complication.

Conclusion and clinical implications: Single crowns supported by 6-mm implants in the posterior region showed high Implant sur-
vival rate in this 36-month follow-up. Prosthetic complications in the sample do not seem to be related to crown-to-implant

ratio, occlusal area or crown volume. Presence and severity of bruxism may contribute to implant failure and prosthetic compli-
cations, but this trend should be confirmed.

© 2014 The Authors
Clinical Oral Implants Research © 2014 John Wiley & Sons A/S

99 | Clin. Oral Impl. Res. 25 (Suppl. 10), 2014