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P l a s m a e f f e c t o n a b u t m e n t s crest (C), the top of the periimplant mucosa (PM) and the apical termination of the junctional epi- thelium (AJE). The following linear measure- ments were performed parallel to the long axis of the implant: the vertical distances between (i) IS and B (IS–B), (ii) IS and C (IS–C), (iii) PM and C (PM–C), and (iv) PM and AJE (PM–AJE). R a n d o m i z a t i o n p r o c e d u r e The dogs randomly received implants in the right or left side of the mandible in the first surgery and in the other side in the next surgery. Imme- diately after implant placement, untreated (as they come from industry; control group) or de- toxified abutments (argon plasma; test group) were randomly assigned to the implant sites. A balanced random permuted block approach was used to prepare the randomization tables to pre- vent an unequal balance between the two groups. A blinded statistician generated the al- location sequence and assigned abutments to sites. Assignment was performed using opaque envelopes containing the generated unique ran- domization code opened immediately after im- plant placement. S t a t i s t i c a l a n a l y s i s Mean values and standard deviations were cal- culated for each outcome variable. Measure- ments of the buccal and lingual aspects were performed, with an accuracy of 0.01 mm. Mean values between the buccal and lingual aspects were obtained. Median and interquartile values were also calculated in order to give a better description of the data set (25th, 50th [median] and 75th percen- tiles). All measurements were rounded to the nearest decimal. Data were pooled for abutment treatment (cleaned or activated titanium implant abutments). The primary variables were IS–C and IS–B. Differences between the test and control sites were analyzed using the nonparametric Mann–Whitney U test. Comparisons between each time point were made by paired tests in order to detect any changes in marginal periim- plant bone levels. All statistical comparisons were conducted at the 0.05 level of signi ficance. Results In total, 64 implants were placed in eight beagle dogs. All of the animals remained in good health during the experimental period and no complica- tions occurred during the healing period. An n = 8 was reached at the one-month period, while an n = 7 was reached at the two-month period be- cause one dog lost implants in the control group. After one month of healing (Table 1), in the test group, at the buccal aspect, IS–B was 1.43 ± 0.99 mm, IS–C was 0.67 ± 0.53 mm, PM–C was 2.61 ± 0.37 mm and PM–AJE was 2.39 ± 0.33 mm. In the control group, IS–B was 1.61 ± 0.74 mm, IS–C was 0.50 ± 0.59 mm, PM–C was 2.59 ± 0.36 mm and PM–AJE was 2.59 ± 0.41 mm. No statistically significant dif- ferences were found between the groups (p > 0.05; Table 1). The median and interquartile values are reported in Table 1. After two months of healing (Table 2), in the test group, IS–B was 1.72 ± 0.70 mm, IS–C was 0.50 ± 0.48 mm, PM–C was 2.59 ± 0.27 mm and PM–AJE was 2.78 ± 0.44 mm. In the control group, IS–B was 2.18 ± 0.71 mm, IS–C was 0.91 ± 0.64 mm, PM–C was 2.86 ± 0.84 mm and PM–AJE was 2.42 ± 0.64 mm. No statisti- cally significant differences were found between the groups (p > 0.05; Table 2). The median and interquartile values are reported in Table 2. The results between the first and the second time points showed no statistically significant differences between the test and control groups, except for PM–AJE of the test group, with higher values observed two months after implant placement (Table 3). Discussion Although cleaning procedures (cleansing with alcohol, soap or steam vapor) at the end of the laboratory phase should be carried out accord- ing to law in the U.S.,21 Europe (EN ISO 17664:2004) and Australia (ADA’s Guidelines for Infection Control, 2015), several microscopic impurities can be detected on the abutment sur- face even after these treatments. Microscopic impurities on the abutment surface due to in- dustrial processes can often be detected also after industrial prepackaging procedures.22 Ad- ditional metallic microparticles mixed with lu- bricant and oxide layers can be produced during the laboratory workflow and adsorbed contam- inants can be accumulated during delivery.17 Such pollution and oxide layers can directly and indirectly trigger a soft- and hard-tissue inflam- matory response or at least alter the interaction with the soft- and hard-tissue environments.15 Journal of Oral Science & Rehabilitation Volume 3 | Issue 2/2017 13