Title	Implants with Microthreaded Collars Show Significantly Less Crestal Bone Loss Than Machined-Collar Implants
Clinical Question	How does crestal bone loss compare after placement of machined-collar implants vs. microthreaded-collar implants within 5 years after loading?
Clinical Bottom Line	Implants with microthreaded collars show significantly less crestal bone loss than machined-collar implants. This was demonstrated by two randomized control trials of significant size. The P values for both studies showed a significant difference between the smooth-collar implant groups and the textured-collar implant groups, with P values of P<0.001 and P=0.004.
Best Evidence
PubMed ID Author / Year Patient Group Study type (level of evidence) 23332435 Nickenig/2013 133 implants in 34 patients Randomized Controlled Trial Key results Measurements were taken at the healing period, 2 years, and 5 years. The machined-surface collar group had a mean crestal bone loss of 1.4 mm at the 5-year postoperative period, while the microthread-collar group had 0.7 mm crestal bone loss at the 5-year mark. At time point, there was a significant difference between the two groups in terms of crestal bone loss (p<0.001). 19961377 Song/2009 40 implants placed in 20 patients Randomized Controlled Trial Key results The average bone loss in the group with microthreads to the top of the implant was 0.16 mm; in the group in which the microthreads stopped short of the implant top, 0.30 mm. The paired t test revealed a significant difference in crestal bone loss between the two groups, with a P value of 0.004.
Evidence Search	(bone loss) AND machined neck implant; dental implants AND alveolar bone loss AND microthreads
Comments on The Evidence	Validity: In the randomized control trial performed by Nickenig and colleagues, 133 implants were placed in 34 patients (70 rough surfaced micro-threaded implants and 60 machined collar implants). All patients presented the same at the start with Kennedy Class I dentition, and all patients completed the study. All patients were treated similarly, with one edentulous site receiving the machined collar implant and the other edentulous site receiving the roughened-surface microthreaded-collar implant. Patients were followed up multiple times up to 5 years, providing adequate follow-up for the study. No conflicts of interested were noted. In the randomized control trial by Song et al, 40 implants were placed in 20 patients. All patients were treated similarly, in that one implant from each group was placed adjacent to the other in the patient’s edentulous space. Radiographs were taken immediately after implant placement, and then again at 1 year postplacement. Bone loss was determined by comparing the two radiographs. The 1-year follow-up timeline was fair for the study. No conflicts of interest were noted.
Applicability	These articles demonstrate the importance of the microthreaded implant surface, and how having that surface extend all the way to the top of the implant is critical to preventing bone loss around the collar of the implant. When trying to maintain the crestal bone level surrounding an implant, this data gives clinicians a solid foundation for the use of microthreaded-collar implants.
Specialty	(General Dentistry) (Oral Surgery) (Periodontics) (Prosthodontics)
Keywords	implants; bone loss; machined collar; micro threaded collar
ID#	2821
Date of submission	03/20/2015
E-mail	cazes@livemail.uthscsa.edu
Author	Casey Cazes
Co-author(s)
Co-author(s) e-mail
Faculty mentor	Ridley Ross, DDS & Barbara McNeill, DMD
Faculty mentor e-mail	rossr@uthscsa.edu; macneill@uthscsa.edu
Basic Science Rationale (Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?) None available
Comments and Evidence-Based Updates on the CAT (FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs) None available