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PROSTHETIC RECONSTRUCTIONS AND REFERRING IMPLANT SURVIVAL IN A POSTGRADUATE PROGRAM : A RETROSPECTIVE STUDY

Table 3 . Number of implants supporting CAD / CAM fabricated ISRs made from zirconium dioxide ( ZrO 2

) and titanium

Type of ISR

Implants in 2005

Implants in 2006

Implants in 2007

Implants in 2008

Implants in 2009

Implants in 2010

Total implants

Total fixed ISR 145 233 205 158 113 199 1053

Total removable ISR 208 247 225 207 213 184 1284

CAD / CAM : computer-aided-design / computer-assisted-manufacturing

ZrO 2

: zirconium dioxide ISR : implant supported reconstruction

Table 4 . Life table analysis reporting on the totally 31 implant failures

Observation period ( year )

Implants at risk ( N )

Implant drop-outs ( N )

Implant failures ( N )

Interval survival (%)

Cumulative survival (%)

Preload 2337 0 12 99.49 99.49 0-1 2325 0 9 99.61 99.10

1-2 2316 294 7 99.70 98.80 2-3 2015 343 1 99.95 98.75 3-4 1671 354 2 99.88 98.63 4-5 1315 410 0 100.00 98.63 5-6 905 464 0 100.00 98.63 6-7 441 379 0 100.00 98.63 7-8 62 59 0 100.00 98.63 8-9 3 3 0 100.00 98.63

frequently to ball anchors and locators . Gradually the computer-aided-design / computer-assistedmanufacturing ( CAD / CAM ) fabrication for prosthesis frameworks and bars was introduced and recently became the prevalent technology 21 . Most frequently the Procera system ( Nobel Biocare , Gothenburg , Sweden ) was used for titanium and zirconium dioxide ( ZrO2 ) reconstructions , followed by Zeno and Lava technology . Subsequently , all bars were milled from homogenous block of titanium grade IV . Milled titanium was also an option for large frameworks of full-arch IBs . In parallel , ZrO2 became the preferred material for all types of fixed prostheses . A close cooperation with laboratory technicians , who were trained and willing to apply modern CAD / CAM techniques , was established . All reconstructions were intended to be screw retained , directly from the implant shoulder without the interposition of an abutment . Thus , optimum implant planning and surgery was required , with proper alignment of the implant axis . 2.5 . Data Collection The present study material covers the data collection of these patients and related treatment , performed during the time period from January 2005 to December 2010 . All necessary information was available from the patients ’ documentation that had to be kept by the graduate students . Additionally all data on implants , surgery procedures and prostheses were registered in a separate excel file . The data collection of the present study was based on the treatment plans , surgical protocols and daily records in the patients ’ charts during the treatment phase and the maintenance care period . The patients ’ age and gender , date of implant placement , implant location and loading time , implant survival , and type of ISR were determined . 2.6 . Statistical analysis The primary outcome was implant survival . The secondary outcome was the type of ISR performed and in particular the specific design and type of material used for the prosthetic reconstruction . Descriptive statistics included mean values , standard deviation ( SD ) and proportional analysis . A life table analysis was performed and the cumulative implant survival rate was calculated . The significance level was 5 %. The SPSS software ( SPSS 18.0 , Chicago , IL , USA ) was used for analysis and graphical illustrations .