title: Effect of Splinting on Dimensional Accuracy of Impressions Made of Implants with Different Subgingival Alignments.
abstract: OBJECTIVE
  Placement of implants at deeper levels of gingiva is sometimes inevitable because of issues like esthetics or bone availability. The accuracy of impressions may be affected in these situations. The aim of this in vitro study was to evaluate the effects of splinting and length of impression copings on the accuracy of impressions made of deeply placed implants.
  
  
  METHODS
  A metal model with two parallel implants (Implantium; Dentium) was fabricated. One hundred and twenty impressions were made using the direct impression technique with and without splinting the impression copings (using short and long impression copings). Impressions were made of implants at three subgingival levels (1, 3, and 6 mm) using regular viscosity poly(vinyl siloxane). The impressions were poured with type IV dental stone. Displacements in the x, y, and z axes, as well as rotational discrepancies and interimplant distances were measured with a coordinate measuring machine. Data were analyzed with Kruskal-Wallis, Mann-Whitney, and nonparametric adjusted rank transform tests.
  
  
  RESULTS
  There was less rotational displacement using longer impression copings at different subgingival positions of the implants, either with splinted or nonsplinted direct technique (p < 0.05). Also, the nonsplinted technique produced more accurate impressions at different apico-coronal levels of implants than the splinted technique using short impression copings (p < 0.05).
  
  
  CONCLUSIONS
  According to the findings of this study, longer impression copings yielded better results than shorter ones in both splinted and nonsplinted techniques. Also, nonsplinted short impression copings produced more accurate impressions than splinted short impression copings.
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.|Dental Research Centre, Dentistry Research Institute and Department of Prosthodontics, Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Elaheh
authors.initials: E
authors.lastname: Beyabanaki
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Ahmed Reza
authors.initials: AR
authors.lastname: Shamshiri
authors.affiliation: Department of Prosthodontics, Faculty of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.|Dental Research Centre, Dentistry Research Institute and Department of Prosthodontics, Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Alikhasi
authors.affiliation: Dental Research Centre, Dentistry Research Institute and Department of Prosthodontics, Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Monzavi
mesh_terms: D000044:Dental Abutments; D015921:Dental Implants; D003761:Dental Impression Technique; D006801:Humans; D003765:Models, Dental; D011145:Polyvinyls; D012833:Siloxanes
chemical_list: D015921:Dental Implants; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane
keywords: Dental implant; direct impression technique; impression technique; splinting procedure