***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND In dentistry , allergic reactions to Ti implants have not been studied , nor considered by professionals . Placing permanent metal dental implants in allergic patients can provoke type IV or I reactions . Several symptoms have been described , from skin rashes and implant failure , to non-specific immune suppression . OBJECTIVE Our objective was to evaluate the presence of titanium allergy by the anamnesis and examination of patients , together with the selective use of cutaneous and epicutaneous testing , in patients treated with or intending to receive dental implants of such material . MATERIAL AND METHODS Thirty-five subjects out of 1500 implant patients treated and /or examined ( 2002 - 2004 ) were selected for Ti allergy analysis . Sixteen presented allergic symptoms after implant placement or unexplained implant failures [ allergy compatible response group ( ACRG ) ] , while 19 had a history of other allergies , or were heavily Ti exposed during implant surgeries or had explained implant failures [ predisposing factors group ( PFG ) ] . Thirty-five controls were r and omly selected ( CG ) in the Allergy Centre . Cutaneous and epicutaneous tests were carried out . RESULTS Nine out of the 1500 patients displayed positive ( + ) reactions to Ti allergy tests ( 0.6 % ) : eight in the ACRG ( 50 % ) , one in the PFG (5.3%)(P=0.009 ) and zero in the control group . Five positives were unexplained implant failures ( five out of eight ) . CONCLUSIONS Ti allergy can be detected in dental implant patients , even though its estimated prevalence is low ( 0.6 % ) . A significantly higher risk of positive allergic reaction was found in patients showing post-op allergy compatible response ( ACRG ) , in which cases allergy tests could be recommended PURPOSE To describe the growth and content of the  prosthodontic  literature over the last 4 decades , to make a prognosis on its probable development in the coming 4 decades and to discuss changes in the content of the International Journal of Prosthodontics ( IJP ) from its start in 1988 to 2004 . METHODS MEDLINE was search ed for articles on prosthodontics published between 1966 and April 2004 . All volumes of IJP were examined with respect to type , subject area and geographic origin of articles . RESULTS Using the term " prosthodontics , " the MEDLINE search produced 66,600 hits . The proportion of clinical studies increased from 1 % during the first 10-year period to 13 % since 2001 . Articles on removable dentures decreased during the period review ed , whereas those on implant prosthodontics increased . R and omized controlled trials were rare and often of inadequate quality . Literature review s have become popular , but many do not follow current guidelines for systematic review s. A marked change in geographic origin of articles in IJP has occurred , with a decrease in material from North America and an increase in that from Europe and Asia . The Internet and open-access publishing will probably have a great impact on the future development of the prosthodontic literature . CONCLUSIONS Substantial changes have occurred in the prosthodontic literature between 1966 and 2004 , and they can be expected to continue with the rapid development of information technology and increased use of the Internet UNLABELLED Implant overdentures and conventional prostheses have been compared in several trials using a variety of functional and oral health-related quality of life ( OHQOL ) outcomes . In this paper , we describe the impact of implant overdentures on general and OHQOL in seniors . OBJECTIVES To compare the oral health-related and general quality of life of seniors ( aged 65 - 75 years ) who received either m and ibular implant overdentures or conventional dentures .  METHODS Sixty edentulous patients were recruited . Thirty received m and ibular overdentures retained by two implants ( IOD ) and a conventional maxillary denture , the other 30 subjects received new maxillary and m and ibular conventional complete dentures ( CD ) . All completed the 20-item version of the Oral Health Impact Profile ( OHIP-20 ) before treatment , then at two and 6 months after delivery of the dentures . The SF-36 general health question naire was completed at baseline and 6 months only . RESULTS Pretreatment and 6-month data from 55 subjects were analyzed . Those who received the IODs had significantly better OHIP-20 total scores at 6 months . Results for IOD subjects were also superior in the functional limitation , physical pain , physical disability and psychological disability subscales . While no significant between group difference was found on the SF-36 health survey , significant pre-post-treatment differences within the IOD group were detected for the role emotional , vitality and the social function scales . CONCLUSIONS M and ibular overdentures retained by two implants provide elderly patients with better OHQOL . General health-related quality of life improved in the implant group This study conducted a longitudinal prospect i ve clinical study of the single-crystal sapphire ( Al2O3 ) cylindrical screw-shaped endosteal dental implant , and attempted to establish clinical parameters to evaluate implant success or failure . Twenty-eight m and ibular implants ( 17 patients ) were placed . After six weeks ' healing , 23 implants in 15 patients served as distal abutments for fixed prostheses ( baseline ) . Implants were evaluated for bleeding index , crevicular fluid volume index , plaque accumulation index , radiographic index , mobility index , and patient comfort . Any implant failing in three of these criteria or implants removed were judged as failures . After 10 years , of the 21 baseline implants recalled ( two implants were lost to recall ) , 17 were fully functional , for an 81 % success rate . The use of qualitative and quantitative clinical evaluation parameters as utilized in this study appears to be important and useful in assessment s of the clinical serviceability of dental implants . These parameters can be used in human clinical trials as well as in experimental animal studies 86 patients , in 2 Sc and inavian centers , participated in a prospect i ve study of m and ibular edentulism , treated with overdentures supported by Bioceram sapphire implants .  Implant success and prosthesis stability as well as parameters for peri-implant health were evaluated . Masticatory function and complications were also documented . The study began in 1991 and clinical treatment of the last patients was completed in 1991 . The patients have been followed for at least 3 years , and up to 12 years . 4 patients were lost to follow-up . Of the initial 324 implants , 7 implants failed before prosthetic treatment . 3 patients lost 1 implant each within the 1st year , and 4 patients lost all 4 implants . 16 implants were lost between 36 and 42 months in function , due to lack of osseointegration and pain . The loss of implants could be attributable to an association , not statistically verified , between bone quality and anatomy , with heavy smoking as a risk factor . Based on the remaining implants , the cumulative implant success rates were 95.2 % , 91.3 % , 91.3 % , 91.3 % at 3 , 5 , 10 and 12 year follow-up respectively . The cumulative success rates for overdentures were 96.4 % , 92.8 % and 92.8 % respectively , for the same follow-up periods . Indices for the health of the peri-implant mucosa disclosed no serious inflammatory reactions in the surrounding soft tissues . Patient satisfaction with this form of oral rehabilitation was high in all but 2 patients who experienced discomfort BACKGROUND A recently introduced implant , the NobelDirect ( Nobel Biocare AB , Göteborg , Sweden ) , has previously been documented with substantial bone resorption in a large number of operated cases . PURPOSE The aim of this study was to evaluate the failure rate of NobelDirect implants  in a retrospective multicenter survey . MATERIAL S AND METHODS A total of 550 NobelDirect implants consecutively placed in over 269 patients at 18 centers were evaluated with regard to failure rate after an average follow-up of about 1 year . RESULTS The overall failure percentage was 10.9 % ( 59 failures ) . The 58 implants not loaded directly showed only one failure ( 1.7 % ) versus 58 failures ( 11.8 % ) of those implants that were loaded directly . A chemical x-ray photoelectron spectroscopy analysis of an implant from the original batch showed up to 3.5 % silicon at parts of the implants . A retrieval analysis of one implant removed at 2 years after placement demonstrated bone resorption down to the level of the fifth thread . CONCLUSIONS It is concluded that the NobelDirect implant , if placed with a punch procedure , ground down in situ , and loaded directly , shows an unusually high failure rate at 1 year 49 patients participated in a prospect i ve study of treatment of total or partial edentulism with fixed prosthodontics supported by Bioceram sapphire implants .  15 patients were treated for maxillary or m and ibular edentulism , and 7 for a missing maxillary anterior tooth . The remaining 27 patients , with Applegate-Kennedy Class I-IV residual dentitions , were treated with fixed bridges supported by free-st and ing implants , or bridges supported by teeth and implants .  Implant success , prosthesis stability , radiographic marginal bone level as well as parameters for peri-implant health were evaluated . The study began in 1982 , and clinical treatment of the last patients was completed in 1988 , i.e. , a follow-up period ranging from 7 to 13 years . Of the patients treated for total m and ibular edentulism , one implant fractured after 6 years in situ . The bone implant score ( BIS ) values for those implants were at the time for the bridge cementation 63.5 + /- 1.4 and at 1 , 2 , 3 and 5 year follow-ups 62.1 + /- 1.4 , 61.9 + /- 1.5 , 61.5 + /- 1.6 , and 60.95 + /- 1.3 , respectively . The success rate was 100 % , 100 % and 97.7 % for the m and ible at 3 , 5 and 10 years , respectively . Of the 7 edentulous patients treated with maxillary fixed bridges , 6 implants in 1 patient had to be removed after 1 year in service . Another 2 patients lost all their implants , 6 each , after 36 months . 6 implants in the 4th patient did not fulfil the criteria for success and were rated as failures at the four year follow-up . The success rate was thus 58.1 % , 44.2 % and 44.2 % for the maxilla at 3 , 5 and 10 year follow-ups , respectively . Of the 7 patients in whom single missing teeth were replaced , 1 implant in the premolar region was lost during the 1st year post-operatively , but no other complications or changes in BIS were observed . Of the 27 patients treated for partial edentulism ( 56 implants total ) 1 implant , of a 4-unit free st and ing maxillary bridge fractured after 6 years and was later replaced . There were no statistically significant differences in BIS changes for the implants when used as abutments for partial maxillary or m and ibular edentulism . The cumulative success rates for the implants in the partially maxilla were 96.3 , 92.6 and 92.6 at the 3 , 5 and 10 years respectively and 100 % in the m and ible over the whole period Titanium dental implants have been used successfully in implantology for more than 40 years . Recent research , however , suggests that titanium might have more side effects than previously believed . Zirconia ceramics have been employed in orthopaedic surgery for approximately 30 years and were recently introduced into dentistry as a metal replacement for crown and bridge work as well as implant abutments . Zirconium dioxide has been shown in both in vitro and in vivo studies to have desirable osseointegrative properties . This clinical study shows that  dental implants  made from zirconia are a feasible alternative to titanium dental implants . In addition to excellent cosmetic results , zirconia implants allow a degree of osseointegration and soft tissue response that is superior to titanium dental implants BACKGROUND Mechanical properties and biocompatibility make zirconia ceramics suitable implant material . The characteristics of tooth-color like , the ability to be machined and the low plaque affinity make zirconia especially suitable as a dental implant material . The influence of surface modification on the osseointegration of this material has not been extensively investigated . PURPOSE Long-term investigations with titanium implants have shown superior biomechanical results with the s and blasted acid-etched ( SLA ) surface , demonstrating a high bone-implant interaction . The objective of this study was to compare two different zirconia surface topographies biomechanically and histologically with the well-documented titanium SLA surface . MATERIAL AND METHODS Zirconia implants with either a machined ( ZrO2 m ) or a s and blasted ( rough , ZrO2r ) surface were manufactured with the exact same cylindrical shape with a st and ard ITI thread configuration as the SLA titanium implants .  The incisors 2 and 3 were removed from both sides of the maxillae of 13 adult miniature pigs and the tissues left to heal for 6 months . After this time period the animals received a total of 78 implants using a r and omized scheme , with the titanium SLA implant used as an only individual reference . After healing periods of 4 , 
    Output:
    
No difference was found in the rate of osseointegration between the different implant material s in animal experiments .
Only cohort investigations were located with question able scientific value .
Alumina implants did not perform satisfactorily and therefore , based on this review , are not a viable alternative to titanium implants .
Currently , the scientific clinical data for ceramic implants in general and for zirconia implants in particular are not sufficient to recommend ceramic implants for routine clinical use .
Zirconia , however , may have the potential to be a successful implant material , although this is as yet unsupported by clinical investigations