Distance between implants has a potential impact of crestal bone resorption

Around dental implants exists a "biologic width" of few millimeters that have to be preserved in order to not have adverse effect on soft and hard tissues around implant. Because the minimum distance between adjacent implants has not been determined yet, we therefore, decided to perform a retrospective study on a series of spiral family implants [SFIs] to verify the minimum inter-implants' distance that has an impact on crestal bone resorption. Fifty-nine implants were investigated with a mean follow-up of 14 months. Implant diameter was 3.75, 4.2, 5 and 6 mm in 11 [18.6%], 29 [49.2%], 17 [28.8%] and 2 [3.4%] SFIs. Implant length was shorter than 13 mm, equal to 13 mm and 16 mm in 23 [39%], 23 [39%] and 13 [22%] SFIs. Implants were inserted to replace 13 incisors [22%], 7 cuspids [11.9%], 30 premolars [50.8%] and 9 molars [15.3%]. Twenty-seven fixtures were inserted in post-extractive sockets and the remaining 32 in healed bone; 36 [61%] were immediately loaded. In addition to the above mentioned implant-related factors, several host- and surgery-factors were investigated. Independent samples T-test, univariate and multivariate analysis were used to detect those variables associated with the clinical outcome. Data were evaluated with a two steps statistical analysis [i.e. univariate and multivariate] after having grouped implants in two series: those with an implant-implant distance less of 1.8 mm and those with an implant-implants distance greater than 1.8 mm. In univariate analysis, post-extractive implants and number of prosthetic units were statistically significant. In multivariate analysis, only post-extractive implants have a significant adverse effect on crestal bone resorption. Adjacent implants inserted with a distance lower and higher than 1.8 mm have difference in crestal bone resorption but this difference is not statistically significant in a short period follow up. This could due to the specific implant used that has a reverse conical neck. No statistical difference was detected between implant subtypes. Post-extractive implant insertion is the major determinant in terms of peri-implant bone resorption in a short period follow-up

Success rate of long implants inserted in fresh frozen bone

To evaluate the clinical out come on a series of long implants inserted into homologue Fresh Frozen Bone [FFB]. This retrospective study was conducted in the period between December 2003 and December 2006, 33 patients were operated on at the Civil Hospital, Castelfranco Veneto, Italy and 85 LIs inserted. The mean follow-up period was 28 months. Implant diameter and length ranged from 3.3 to 5.0 mm and from 14 to 16 mm, respectively. No implants were lost [i.e. SRV = 100%] and no differences were detected among the studied variables, On the contrary, Cox regression showed that implant diameter [i.e. narrow - implants, diameter 3, 75 mm] and prosthetic restoration [i.e. removable dentures] correlated with a statistically significant lower delta IAJ [i.e. reduced crestal bone loss] and thus a better clinical outcome. FFB is a good material to be used in pre-prosthetic surgery. LIs inserted into FFB can be considered reliable, although a higher marginal bone loss has to be expected when wider implants and fixed prosthetic restorations are used