the ethical committee of the university hospitals of geneva , geneva , switzerland , approved the protocol . research was conducted according to the principles outlined in the declaration of helsinki on human medical experimentation . , 34 participants were recruited from individuals seeking treatment at the school of dental medicine , university of geneva . eligible participants were adults aged 20 or over , systemically healthy , with tooth loss treatable by the insertion of implants and single - unit crowns . a bone substrate sufficient in quality and volume to allow proper anchorage of the implants was a prerequisite . it was required that the participant could be treated as a regular patient under standard clinical conditions . thus , persons with an increased risk for complications , that is , those with current major systemic or oral pathologies , or subjects needing extensive preparatory treatments of hard or soft tissues in order to make implant placement possible , were not included . the following conditions were explicit exclusion criteria : smoking more than 10 cigarettes per day , addicted to alcohol or other substances , heavily overweight , severely compromised general health , extensive bone loss in the area of prospective implantation , not willing to attend regular dental maintenance care and follow up evaluations , poor oral hygiene , that is , full - mouth plaque score ( fmps ) > 20% . the participants were treated with the zeramex t implants system ( dentalpoint ag , zrich , switzerland ) , an all - ceramic implant system intended to replace missing teeth in partially edentulous patients . the product consists of an implantable device and an abutment , both made from highly dense zirconium dioxide ( zro2-atz - bio - hip , metoxit ag , thayngen , switzerland ) , and the instruments and accessory parts to insert the device in the jawbone and to install the prosthodontic suprastructure . implants of three diameters ( 3.5 , 4.2 , 5.5  mm ) and three lengths ( 8 , 10 , 12  mm ) were available . the abutments were bonded into the implants with an adhesive resin cement ( panavia f , kuraray , tokyo , japan ) . full - ceramic crowns were made from lithium disilicate glass ceramic ( ips e.max press , ivoclar vivadent ag , schaan , lichtenstein ) . if necessary , the teeth of the participants were cleaned to remove plaque , stain , and calculus prior to surgery . treatment was not commenced unless the mucosa of recipient and neighboring sites was looking healthy and all extraction sites were healed . the implants were selected and inserted according to the manufacturer 's recommendations and guidelines by a single experienced clinician , a certified periodontist with specific training in implant dentistry ( n.c . ) . under local anesthesia , a mid - crestal incision was made , and a full - thickness flap was elevated to expose the alveolar ridge . if necessary , the flap was extended horizontally by intrasulcular incisions around neighboring teeth ; vertical releasing incisions were avoided . after perforating the cortical bone with a 2-mm - diameter round bur , the initial osteotomy was realized with a 2.3-mm - diameter pilot drill and then enlarged using a sequence of twist drills . as an example , to place a 3.5-mm - diameter implant , the osteotomy was accomplished using a 2.3-mm and a 3.5-mm drill . the preparation was finalized with a tapering drill corresponding to the shape of the implant . if considered necessary , the local bone was augmented with a xenogenic bone mineral and a collagen membrane ( biooss and bioguide , geistlich pharma , wolhusen , switzerland ) in the same session . depending of the soft tissue thickness , either a healing cap or a gingiva former was fitted on the implant to achieve a non - submerged healing . after a healing period of 3  months data were collected before the placement of the implant ( visit 1 ) , immediately upon placement of the implant ( visit 2 ) , immediately after the insertion of the suprastructure ( visit 3 ) , and 1  year ( 2  weeks ) after loading ( visit 4 ) . the clinical evaluation included the inspection of dental and periodontal conditions of neighboring teeth , implant mobility , local modified plaque index ( mpli ) , modified sulcus bleeding index ( mbi ) ( mombelli et  al . 1987 ) , peri - implant probing depth ( ppd ) , and the presence or the absence of suppuration upon probing at six sites ( mesial - buccal , mid - buccal , distal - buccal , mesial - lingual , mid - lingual , distal - lingual ) of the implant . upon crown placement , and 1  year thereafter , the patients were asked to rate satisfaction on a visual analog scale ( vas ) by placing a mark on a horizontal line , 100  mm long , labeled with  fully satisfied with the outcome  at one end and with  not at all satisfied  at the other . periapical radiographs were taken before implant placement , after surgery , upon placement of the suprastructure , and 1  year after loading . the rates of success , failure , and complications were expressed as frequency per first year after loading for all implants . cumulative rates were calculated after 1 and 2  years using the method of kaplan  meier ( kaplan & meier 1958 ) . between november 2010 and june 2012 , 34 participants were recruited from individuals seeking treatment at the school of dental medicine , university of geneva . eligible participants were adults aged 20 or over , systemically healthy , with tooth loss treatable by the insertion of implants and single - unit crowns . a bone substrate sufficient in quality and volume to allow proper anchorage of the implants was a prerequisite . it was required that the participant could be treated as a regular patient under standard clinical conditions . thus , persons with an increased risk for complications , that is , those with current major systemic or oral pathologies , or subjects needing extensive preparatory treatments of hard or soft tissues in order to make implant placement possible , were not included . the following conditions were explicit exclusion criteria : smoking more than 10 cigarettes per day , addicted to alcohol or other substances , heavily overweight , severely compromised general health , extensive bone loss in the area of prospective implantation , not willing to attend regular dental maintenance care and follow up evaluations , poor oral hygiene , that is , full - mouth plaque score ( fmps ) > 20% . the participants were treated with the zeramex t implants system ( dentalpoint ag , zrich , switzerland ) , an all - ceramic implant system intended to replace missing teeth in partially edentulous patients . the product consists of an implantable device and an abutment , both made from highly dense zirconium dioxide ( zro2-atz - bio - hip , metoxit ag , thayngen , switzerland ) , and the instruments and accessory parts to insert the device in the jawbone and to install the prosthodontic suprastructure . implants of three diameters ( 3.5 , 4.2 , 5.5  mm ) and three lengths ( 8 , 10 , 12  mm ) were available . the abutments were bonded into the implants with an adhesive resin cement ( panavia f , kuraray , tokyo , japan ) . full - ceramic crowns were made from lithium disilicate glass ceramic ( ips e.max press , ivoclar vivadent ag , schaan , lichtenstein ) . if necessary , the teeth of the participants were cleaned to remove plaque , stain , and calculus prior to surgery . treatment was not commenced unless the mucosa of recipient and neighboring sites was looking healthy and all extraction sites were healed . the implants were selected and inserted according to the manufacturer 's recommendations and guidelines by a single experienced clinician , a certified periodontist with specific training in implant dentistry ( n.c . ) . under local anesthesia , a mid - crestal incision was made , and a full - thickness flap was elevated to expose the alveolar ridge . if necessary , the flap was extended horizontally by intrasulcular incisions around neighboring teeth ; vertical releasing incisions were avoided . after perforating the cortical bone with a 2-mm - diameter round bur , the initial osteotomy was realized with a 2.3-mm - diameter pilot drill and then enlarged using a sequence of twist drills . as an example , to place a 3.5-mm - diameter implant , the osteotomy was accomplished using a 2.3-mm and a 3.5-mm drill . the preparation was finalized with a tapering drill corresponding to the shape of the implant . if considered necessary , the local bone was augmented with a xenogenic bone mineral and a collagen membrane ( biooss and bioguide , geistlich pharma , wolhusen , switzerland ) in the same session . depending of the soft tissue thickness , either a healing cap or a gingiva former was fitted on the implant to achieve a non - submerged healing . after a healing period of 3  months data were collected before the placement of the implant ( visit 1 ) , immediately upon placement of the implant ( visit 2 ) , immediately after the insertion of the suprastructure ( visit 3 ) , and 1  year ( 2  weeks ) after loading ( visit 4 ) . the clinical evaluation included the inspection of dental and periodontal conditions of neighboring teeth , implant mobility , local modified plaque index ( mpli ) , modified sulcus bleeding index ( mbi ) ( mombelli et  al . 1987 ) , peri - implant probing depth ( ppd ) , and the presence or the absence of suppuration upon probing at six sites ( mesial - buccal , mid - buccal , distal - buccal , mesial - lingual , mid - lingual , distal - lingual ) of the implant . upon crown placement , and 1  year thereafter , the patients were asked to rate satisfaction on a visual analog scale ( vas ) by placing a mark on a horizontal line , 100  mm long , labeled with  fully satisfied with the outcome  at one end and with  not at all satisfied  at the other . periapical radiographs were taken before implant placement , after surgery , upon placement of the suprastructure , and 1  year after loading . the rates of success , failure , and complications were expressed as frequency per first year after loading for all implants . cumulative rates were calculated after 1 and 2  years using the method of kaplan  meier ( kaplan & meier 1958 ) . thirty - four patients were initially included ; however , two of them turned out to have an increased risk for complications , and consequently were excluded : one because of smoking more than 10 cigarettes per day , one because of extensive bone loss in the area of prospective implantation . the mean age of the 32 participants was 51.9  years , range 2475 , 56% were female , and 13% were smokers . twenty - one participants received a single implant , eight participants received two implants , two participants received three implants , one patient received six implants . twenty - five implants were placed in the lower , and 24 in the upper jaw . the intraosseous implant lengths were 8  mm ( eight implants ) , 10  mm ( 29 implants ) , or 12  mm ( 12 implants ) . thirteen implants had a diameter of 5.5  mm , 35 implants had a diameter of 4.2  mm , and one implant had a diameter of 3.5  mm . in one case , the local bone was augmented laterally in the region of the upper left first premolar . ( a , b ) photograph and radiograph of one case on day of surgery . all implants were placed as intended , in sites with a sufficient width of keratinized mucosa , and primary stability was reached in all cases . three months after surgery , all implants were stable , with one exception : one implant showed mobility upon inspection , indicating absence of osseointegration . the implant had a diameter of 4.2  mm , a length 10  mm , and replaced a right lower first molar . the patient had not noted anything wrong and was free of pain or discomfort . the site was curetted to induce bleeding and was subject to open healing , which was uneventful . a check of the medical and dental history revealed no specific risk factors for implant loss , except that this patient had already lost another implant at the same site previously . zirconia abutments were connected , and single - unit full - ceramic crowns were fitted on 48 implants in 31 patients . on average , all participants were very satisfied with the outcome at the time of crown cementation ( 4  mm mean vas score on a scale from 0 to 100  mm , 13  mm maximum score ) . two patients were lost to follow - up : one patient with one implant could not be contacted any longer due to moving out of the country . one patient with one implant was lost due to death for reasons unrelated to the study ( cardiac arrest ) . the residue of the fractured abutment was removed , a new abutment was inserted , and a new crown was fitted successfully . the first incident occurred in the region of the first upper left molar , 10  days after crown placement . an investigation revealed a technical error due to a communication problem between the clinic and the laboratory . the second incident occurred in the region of the lower left first molar , 8  months after crown placement . five implants were lost , one 3  months after loading ( diameter 4.2  mm , length 8  mm , region of right upper first premolar ) , one after 5  months ( diameter 5.5  mm , length 10  mm , region of right lower first molar ) , two after 6  months ( left upper second premolar : diameter 4.2  mm , length 10  mm ; right lower first molar : diameter 5.5  mm , length 10  mm ) , and one after 10  months ( diameter 4.2 , length 10  mm , region of left upper second premolar ) . the first four failures occurred in patients , where only one implant had been placed , the fifth happened in a patient with six implants . in all cases , the clinical circumstances were alike : mobility , not accompanied by pain or discomfort , was suddenly noted . the clinical exam showed healthy - looking peri - implant tissues with no signs of inflammation or infection ( fig.4 ) . no specific causes or risks for implant failure could be identified on the level of the site or the subject . the remaining 41 implants have been followed for 588174  days after loading ( range 369889  days , 10/10/2013 ) . thirteen implants in nine patients have been followed up for more than 2  years . no technical or biological complications other than the ones described above were revealed at the 1-year control visit or at a later time . after 1  year , all patients continued to be very satisfied with the results of therapy ( 4  mm mean vas score on a scale from 0 to 100  mm , 12  mm maximum score ) . an inspection of the peri - implant tissues revealed no visible signs of inflammation such as redness or swelling in any case . no sites showed suppuration or marked bleeding upon probing ( mbi score > 1 ) . no plaque could be seen by the naked eye ( mpli score > 1 ) . the comparison of radiographs taken upon placement of the suprastructure and 1  year after loading revealed no bone loss > 1  mm . clinical status of peri - implant tissues monitored at six sites ( mesial - buccal , mid - buccal , distal - buccal , mesial - lingual , mid - lingual , distal - lingual ) at each implant . data are means    standard deviation ( ppd ) , or numbers and frequency ( % ) of positive sites the cumulative survival rates ( sr ) 1 and 2  years after loading were 87% implants ( table2 ) . the cumulative soft tissue complication rate was 0% , the cumulative technical complication rate was 4% implants , the cumulative complication rate for bone loss > 2  mm was 0% , and the cumulative esthetic complication rate was 0% . lifetable analysis for placed implants the 1- and 3-year outcomes of 27 first - generation zeramex implants are presented here as ancillary data . these implants were placed in 20 patients from november 2009august 2010 and are routinely monitored since then . in two of these patients , implants were used to replace seven premolars and 20 molars , 18 in the lower , and nine in the upper jaw . the intraosseous implant lengths were 8  mm ( five implants ) , 10  mm ( 12 implants ) , and 12  mm ( 10 implants ) . all implants were placed as intended , and primary stability was reached in all cases . after 3  months , all implants were stable , indicating the presence of an osseointegration . zirconia abutments were bonded into the implants , and single - unit full - ceramic crowns were fitted . four implants in four different patients showed mobility and had to be removed due to aseptic loosening : two after 2  weeks , one 4  months and one 6  months after loading . the other implants have been followed up 39    3  months after loading ( range 3545  months ) . no further implants were lost , and no signs of peri - implant infections were noted . on one crown , the 1-year survival rate was 85% implants , the survival from 1 to 3  years was 100% , and thus , the cumulative 3-year survival rate was 85% implants . including the data from 20 patients treated with an earlier version of the system , an over - all 2-year cumulative survival rate of 86% was calculated for a total of 76 two - piece zirconia implants supporting all - ceramic crowns in 52 patients . thirty - four patients were initially included ; however , two of them turned out to have an increased risk for complications , and consequently were excluded : one because of smoking more than 10 cigarettes per day , one because of extensive bone loss in the area of prospective implantation . the mean age of the 32 participants was 51.9  years , range 2475 , 56% were female , and 13% were smokers . twenty - one participants received a single implant , eight participants received two implants , two participants received three implants , one patient received six implants . these implants replaced one missing incisor , 23 premolars , and 25 molars . twenty - five implants were placed in the lower , and 24 in the upper jaw . the intraosseous implant lengths were 8  mm ( eight implants ) , 10  mm ( 29 implants ) , or 12  mm ( 12 implants ) . thirteen implants had a diameter of 5.5  mm , 35 implants had a diameter of 4.2  mm , and one implant had a diameter of 3.5  mm . in one case , the local bone was augmented laterally in the region of the upper left first premolar . ( a , b ) photograph and radiograph of one case on day of surgery . all implants were placed as intended , in sites with a sufficient width of keratinized mucosa , and primary stability was reached in all cases . three months after surgery , all implants were stable , with one exception : one implant showed mobility upon inspection , indicating absence of osseointegration . the implant had a diameter of 4.2  mm , a length 10  mm , and replaced a right lower first molar . the site was curetted to induce bleeding and was subject to open healing , which was uneventful . a check of the medical and dental history revealed no specific risk factors for implant loss , except that this patient had already lost another implant at the same site previously . zirconia abutments were connected , and single - unit full - ceramic crowns were fitted on 48 implants in 31 patients . on average , all participants were very satisfied with the outcome at the time of crown cementation ( 4  mm mean vas score on a scale from 0 to 100  mm , 13  mm maximum score ) . two patients were lost to follow - up : one patient with one implant could not be contacted any longer due to moving out of the country . one patient with one implant was lost due to death for reasons unrelated to the study ( cardiac arrest ) . the residue of the fractured abutment was removed , a new abutment was inserted , and a new crown was fitted successfully . the first incident occurred in the region of the first upper left molar , 10  days after crown placement . an investigation revealed a technical error due to a communication problem between the clinic and the laboratory . the second incident occurred in the region of the lower left first molar , 8  months after crown placement . five implants were lost , one 3  months after loading ( diameter 4.2  mm , length 8  mm , region of right upper first premolar ) , one after 5  months ( diameter 5.5  mm , length 10  mm , region of right lower first molar ) , two after 6  months ( left upper second premolar : diameter 4.2  mm , length 10  mm ; right lower first molar : diameter 5.5  mm , length 10  mm ) , and one after 10  months ( diameter 4.2 , length 10  mm , region of left upper second premolar ) . the first four failures occurred in patients , where only one implant had been placed , the fifth happened in a patient with six implants . in all cases , the clinical circumstances were alike : mobility , not accompanied by pain or discomfort , was suddenly noted . the clinical exam showed healthy - looking peri - implant tissues with no signs of inflammation or infection ( fig.4 ) . no specific causes or risks for implant failure could be identified on the level of the site or the subject . the remaining 41 implants have been followed for 588174  days after loading ( range 369889  days , 10/10/2013 ) . thirteen implants in nine patients have been followed up for more than 2  years . no technical or biological complications other than the ones described above were revealed at the 1-year control visit or at a later time . after 1  year , all patients continued to be very satisfied with the results of therapy ( 4  mm mean vas score on a scale from 0 to 100  mm , 12  mm maximum score ) . an inspection of the peri - implant tissues revealed no visible signs of inflammation such as redness or swelling in any case . no sites showed suppuration or marked bleeding upon probing ( mbi score > 1 ) . no plaque could be seen by the naked eye ( mpli score > 1 ) . the comparison of radiographs taken upon placement of the suprastructure and 1  year after loading revealed no bone loss > 1  mm . clinical status of peri - implant tissues monitored at six sites ( mesial - buccal , mid - buccal , distal - buccal , mesial - lingual , mid - lingual , distal - lingual ) at each implant . data are means    standard deviation ( ppd ) , or numbers and frequency ( % ) of positive sites the cumulative survival rates ( sr ) 1 and 2  years after loading were 87% implants ( table2 ) . the cumulative soft tissue complication rate was 0% , the cumulative technical complication rate was 4% implants , the cumulative complication rate for bone loss > 2  mm was 0% , and the cumulative esthetic complication rate was 0% . the 1- and 3-year outcomes of 27 first - generation zeramex implants are presented here as ancillary data . these implants were placed in 20 patients from november 2009august 2010 and are routinely monitored since then . in two of these patients , implants were used to replace seven premolars and 20 molars , 18 in the lower , and nine in the upper jaw . the intraosseous implant lengths were 8  mm ( five implants ) , 10  mm ( 12 implants ) , and 12  mm ( 10 implants ) . all implants were placed as intended , and primary stability was reached in all cases . after 3  months , all implants were stable , indicating the presence of an osseointegration . zirconia abutments were bonded into the implants , and single - unit full - ceramic crowns were fitted . four implants in four different patients showed mobility and had to be removed due to aseptic loosening : two after 2  weeks , one 4  months and one 6  months after loading . the other implants have been followed up 39    3  months after loading ( range 3545  months ) . no further implants were lost , and no signs of peri - implant infections were noted . on one crown , the 1-year survival rate was 85% implants , the survival from 1 to 3  years was 100% , and thus , the cumulative 3-year survival rate was 85% implants . including the data from 20 patients treated with an earlier version of the system , an over - all 2-year cumulative survival rate of 86% was calculated for a total of 76 two - piece zirconia implants supporting all - ceramic crowns in 52 patients . the primary aim of the present prospective clinical study was to evaluate the 1-year outcomes of a new two - piece ceramic implant system , restored with single - unit full - ceramic crowns . the cumulative survival rate , 1  year and 2  years after loading , was 87% implants . a common failure pattern , which was the only reason for implant loss , clearly emerged : the mobility of the implant suddenly increased , while there were no preceding or concurrent signs of infection ( redness , swelling , bleeding , suppuration , or pain ) or a technical problem . the analysis of one retrieved implant by scanning electron microscopy evidenced complete absence of bony residues on the implant surface . altogether , these findings suggest that there was sudden mechanical breakdown of the interface between the implant and the bone . aseptic loosening  is used , has been described in the orthopedic literature ( allain et  al . osteolysis seems to be induced by wear debris modulating the expression of rank-b / ranl and osteoprotegerin ( gehrke et  al . apart from this phenomenon , and except the fracture of two abutments that could be replaced , up to now no further problems occurred in our study . survival rates ranging from 74% to 98% after 1256  months have been reported for one - piece zirconia implants by other investigators ( for review see depprich et  al . 2014 ) . in one prospectively followed cohort , the cumulative survival rate was 95% implants after 1  year ( kohal et  al . however , a mean bone loss of 1.3  mm from implant insertion to the 1-year evaluation was noted . a total of 34% implants lost more than 2  mm , and 14% lost more than 3  mm of bone . according to clinical judgment , this bone loss was not associated with inflammation . in our study , similar peri - implant bone loss was not observed . another study ( pirker & kocher 2009 ) evaluated non - submerged , root - analog zirconia implants with two different surfaces in 18 patients for immediate replacement of single - rooted teeth . in one group , implant surfaces were roughened by sandblasting only ; in the other group , additional macro - retentions were provided . all implants were lost within 2  months in the first group , while a 92% survival rate was reported for 133  months in the second group , with minimal bone resorption and soft tissue recession . a recent animal study provided histo - morphometric data on the impact of surface properties of zirconium implants on osseointegration , indicating favorable effects of acid etching ( saulacic et  al . another randomized clinical trial evaluated the survival and success of one - piece zirconia implants , placed either immediately in post - extraction sockets or healed sites ( cannizzaro et  al . five implants ( 12.5% ) were lost within 10  days to 2  months after loading . four of the failing implants were placed as post - extractive implants ; three of them were subject to immediate occlusal loading . the average bone loss was 0.9  mm for immediately loaded implants and 0.7  mm if the implants were not loaded immediately . one - piece zirconia dental implants with three different roughened surfaces have been evaluated up to 5  years year in 378 patients ( oliva et  al . . the overall implant success rate of 831 implants was 95% after 3.4    0.2  years . the success rate of the acid - etched surface group was significantly better than that of the other two . as in our study , failures were clustering in the first year after loading . in the present study , the 1-year clinical exam evidenced healthy conditions of the peri - implant tissues throughout the entire cohort . no sites showed suppuration , redness , swelling , or marked bleeding upon probing ( mbi score > 1 ) . 1992 ) , isolated bleedings spots , as seen at 27% sites in our sample ( mbi score 1 ) , are to be expected even in the absence of inflammation due to mechanical tissue stimulation . it has already been speculated that inflammatory reactions are less expressed in peri - implant tissues in contact with zirconia than titanium surfaces . a comparative immuno - histochemical evaluation of human peri - implant soft tissues associated with either titanium or zirconium oxide healing caps revealed more inflammatory infiltrate in the titanium specimens , with higher expression of vegf and nos , higher proliferative activity , and micro - vessel density ( degidi et  al . replacement of single teeth in the posterior area was possible with this new full - ceramic implant system .
objectivesthe aim of this prospective clinical study is to evaluate the safety and efficacy of a new all - ceramic implant system to replace missing teeth in partially edentulous patients.material and methodsthirty - two partially edentulous , systemically healthy patients were treated with 49 two - piece zirconia implants ( zeramex t implant system ) . 
 zirconia abutments were connected with adhesive resin cement . 
 single - unit full - ceramic crowns were cemented . 
 the cases have been followed for 588174  days after loading ( range 369889  days ) . 
 all patients have been re - evaluated 1  year after loading.resultsthe cumulative survival rate 1  year after loading was 87% implants . 
 all failures were the result of aseptic loosening , and no implants were lost after the first year . 
 the results of the other cases were good , and the patients were very satisfied . 
 the cumulative soft tissue complication rate was 0% , the cumulative technical complication rate was 4% implants , the cumulative complication rate for bone loss > 2  mm was 0% , and the cumulative esthetic complication rate was 0% . including the data from 20 patients treated with an earlier version of the system , an over - all 2-year cumulative survival rate of 86% was calculated for a total of 76 two - piece zirconia implants supporting all - ceramic crowns in 52 patients.conclusionsreplacement of single teeth in the posterior area was possible with this new full - ceramic implant system . 
 failures were due to aseptic loosening .