Introduction
The different ways in rehabilitation of partially edentulous jaws with implants have been published in literature. In addition to exclusively implant supported fixed dental prosthesis, tooth implant supported fixed dental prosthesis also promise a successful and predictable outcome.1, 2, 3 The biomechanical differences between natural teeth and implants have been previously recognized through in vivo and in vitro studies which has shown that both implant and tooth shares the load that was applied to tooth implant supported fixed dental prosthesis. 4, 5
Implant tooth supported fixed dental prosthesis is recommended in only in situations where there is anatomical limitations (posterior region of mandible before mental foramen or maxillary sinus), financial restriction ,minimally invasive surgery, alveolar bone deficiency requiring augmentation procedures, long pontic span or cantilever segments, nerve repositioning and splinting periodontally involved teeth or any event of implant failure.6, 7, 8, 9, 10, 11 It may also be used when few or unfavorable distribution of teeth remains as sole abutments to support a fixed dental prosthesis. 12, 13
A key factor in an implant tooth fixed dental prosthesis is the differential mobility between the tooth and the implants. Teeth mobility is around 10 times greater than the mobility of the implants due to presence of periodontal ligament in tooth. 14 Others advocated that a differential mobility of 5:1 between natural teeth and implant will eventually lead to tooth implant supported prosthesis borne completely on implants. 15
This will lead to biological and mechanical complications like implant failure, prosthesis failure, tooth intrusion, prosthesis screw loosening, fixed dental prosthesis framework fracture, signs of peri implantitis such as deepening of peri implant pocket probing depth, implant marginal bone loss.16, 17
Several reports on tooth abutment intrusion in implant tooth supported fixed dental prostheses have been published. Consensus exists on tooth intrusion, debris impaction, impaction, impaired rebound memory, mechanical binding.18 After more than few decades of controversial results, implant tooth supported fixed dental prosthesis even today remains an unsolved issue. Implant tooth fixed dental prothesis have demonstrated comparable results regarding the technical and biological complications between these two treatments.19 Both the rigid and non-rigid methods connection between teeth and implants have been employed in the past. 20, 21, 22 Abutment intrusion was reported more when non-rigid connectors was used. 23
The aim of this systemic review and meta- analysis was to identify studies which compared implant tooth supported fixed dental prosthesis and exclusively implant supported fixed dental prosthesis for assessments of implant failure, prosthesis failure, abutment tooth failure and other biological and mechanical failures. The big question has still not been answered despite several studies that have been conducted previously too, hence the systematic review was done to help allow for the answers for the same.
Materials and Methods
This systematic review was performed according to the guidelines of the PRISMA (Preferred Reporting Items for Systematic reviews and meta-analysis statement.)
The initial electronic database search on PubMed/MEDLINE, Science Direct and Google Scholar resulted in 143 titles. After screening the abstracts, 47 relevant titles were selected by two independent reviewers and 96 were excluded for not being related to the topic. Hand searching of the reference lists of the selected studies did not deliver additional papers. Upon reading the full texts, 5 studies were excluded for the following reasons: they were review articles, in vitro studies, meta- analysis, case series, case reports, clinical trials, retrospective studies, without control group and due to data duplication.
After pre-screening, application of the inclusion and exclusion criteria and handling of the question of our systematic review, seven studies remained (Figure 1: Prisma flowchart). They were used for data extraction and data analysis.
The study outcomes further divided from the included studies were as follows: Primary outcomes:
Prosthesis Stability
Implant Failure Secondary outcomes:
Biological complications- Marginal bone loss
Other technical complications PICOS Question
Patients: Partially edentulous patients Intervention: restored with implant tooth supported fixed dental prosthesis (ITSFPD) Comparison: Restored with implant supported fixed dental prostheses (FSIS) Outcome: Survival of fixed dental prostheses and/or implants and complications after an observation period of at least two years.
Inclusion criteria were: 1, 3, 4, 10, 12, 24, 25, 26, 27, 28
Prospective clinical studies with a control group
Systemically and psychologically healthy individuals
Absence of para functional habits
Sound, caries free abutment teeth without any clinical or radiographic evidence of periodontitis or any other periodontal condition
Partial edentulism in either maxillary or mandibular arch
At least 10 patients included.
Observation period post implant loading of at least 2 years
Language of publication: English
Smoking less than 10 cigarettes per day
No previous experience of wearing partial dentures
Literature Search Strategy
Three electronic databases (Medline/PubMed, Cochrane Library, and Embase) were searched for articles published between January 1988 and May-June 2021. In addition, a search for grey literature was also performed. All the relevant articles were read in full text.
Manual search of the following journals was performed as well with following data base:
Search items used for the study
The search was performed using the terms (Implant* AND outcome OR survival OR failure* OR complication) AND (fixed dental prostheses OR fixed partial dentures), (Tooth-implant AND outcome OR survival OR failure* OR complication) AND (fixed dental prostheses OR fixed partial dentures), AND (tooth implant support* OR implant support* OR prosthesis) AND (tooth implant connection OR connecting teeth to implants OR combined tooth implant support) AND (biological complication* OR technical complication* OR tooth intrusion ORtooth fracture OR prosthesis fracture OR screw loosening OR implant failure).
Study selection
Two reviewers independently screened titles and abstracts for relevance. Potential full texts of articles were read and assessed according to inclusion criteria. Any disagreement was solved by discussion with a third reviewer and the fourth reviewer.
Case included was with loading implant after follow-up period between 12 or 24 months.(Table 1)
Study Observation time – 1990-2021.
Data analysis
The data was extracted from the selected articles and was recorded electronically in excel sheets. Relative risk was calculated for prosthetic failure. Mean and Analysis of Variance was calculated for marginal bone loss. Value of Central tendency was calculated for plaque index and probing depth.
All calculations were performed in SPSS (Statistical Package for Social Sciences) VERSION 26.0.0. Result was considered significant for P< 0.05.
Results
Study characteristics 1, 3, 4, 10, 24, 25, 26, 27, 28(Table 1) Demographics and study outcomes
The study outcomes further divided from the included studies were as follows: Prosthesis stability
After careful screening 7 articles were found within the scope of this review and data meta-analysis was done.
Demographics and study outcomes
We established a database into which we entered the information extracted from each paper. Out of 7 studies, 3 originated from Sweden, rest other (1 each) were from Belgium, Switzerland, Turkey and Egypt. 1 study was a randomized control trial. In these studies, overall, a total of 224 implants were evaluated for marginal bone loss, implant survival, tooth and implant mobility, prosthesis stability, tissue reactions, sensory disturbances, technical complications. 156 (44.83%) implant tooth supported fixed dental prostheses (ITSFPD) were compared with 192 (55.17%) implant supported fixed dental prostheses (FSIS)(Table 1). Follow-up duration of studies varied from 1 to 14 years, 5 implant systems were used which included Nobel BioCare (2), Modem Branemark (3), TSV Zimmer (2), ITIA Dental Implant system (1) and Gothenburg Sweden (1) system.
Prosthetic stability: (Table 2,Figure 2)
Gunne in his study found Prosthetic stability in 18 out of 20 in tooth implant (TI) group and 16 out of 20 in implant implant (II) group. Relative risk (RR) calculation shows a value of 0.88 with Confidence interval (CI) from 0.6831 to 1.1567. Similarly, in Olssun’s data RR was 0.9 with CI of 0.7099 to 1.1409, Lindh’s RR was 0.9583 with CI 0.8326 to 1.1030 and Bragger’s RR was 0.9625 and CI of 0.8300 to 1.1161. Honsy’s, Acka’s as well as Mostafa’s data RR was 1 with CI of 1 to 1. [Table 2, Figure 2] Overall relative risk calculated was 1.0328 with CI of 0.9747 to 1.0987. p-value was 0.2623 and it was not significant.
Marginal Bone loss: (Table 2,Figure 3)
Except from Bragger, data of mean marginal bone loss after 2 years of follow- up was available from rest 6 studies mean bone loss in tooth and implants are shown in Table 2, Figure 3. ANOVA test was run on the results which yielded f-ratio value of 0.49412 and accordingly the p-value is 0.49.
Although MBL was less in tooth implant (TI) group but the results were not significant at p < .05.
Implant failure:(Table 2)
Many authors were not clear about the implant failure in treatment groups. Overall, 20 implants failed in the study.
Table 1
Assessment of different studies included in the systematic review and meta-analysis
|
S.No. |
Author and Year |
Type of study |
Origin |
Subject No.(M/F) |
Mean age (year) |
Comparisons |
Follow up duration |
Implant system used |
Follow up Criteria |
Outcome |
|
1 |
Gunne4 et al 1992 |
RCT |
Sweden |
23; 8M, 15F |
57.7 |
23 ITSFDP; 23 FSIS |
10 Years |
Nobel Biocare |
Implant survival, MBL, Mobility bridge stability, Tissue reaction, sensory disturbances |
TI is better in bridge survival, and had less MBL than II |
|
2 |
Olsson 28 |
NCRT with equal compare group |
Sweden |
23 |
58 |
23 ITSFDP; 23 FSIS |
5 Years |
Modern Branemark |
Implant survival, Bridge stability, MBL, Mobility of teeth, Marginal tissue reaction, Sensory disturbance |
Failure of T1>II; No difference in MBL between both groups |
|
3 |
Hosny26 et al 2000 |
NCRT with equal compare group |
Beigium |
18; 12F, 6M |
49.5 |
30 ITSFDP; 48 FSIS |
1 year to 14 years |
Branemark system |
Implant outcome, marginal bone stability, Mechanical disturbance |
No difference FSIS offer a more versatile solution |
|
4 |
Lindh10 et al 2001 |
Prospective comparative group |
Sweden |
26; 11M, 15F |
49-84 |
26 II; 26 TI |
2 years |
Branemark system A, Nobel biocare AB, Gothenburg, Sweden |
Implant success, Prosthesis stability, MBL, Tissue reactions, Mobility |
More MBL in II than TI |
|
5 |
Bragger1 et al 2001 |
Prospective three parallel group comparative study |
Switzerland |
85; 53F, 32M |
55.7 |
Group II; 33 pts with 40 FDP, Group TT: 40 pts with 58 FDP, Group IT: 15 pts with 18 FPD |
2-3 years |
ITIA dental implant system |
Plaque index, Gingival index, Recession, Probing pocket depth, Probing attachment level |
TI> II=TI |
|
6 |
Akca4 et al 2008 |
Prospective parallel group comparative study with unequal group |
Turkey |
29; 13M, 16F |
48.3 |
29 ITSFDP; 29 FSIS |
2 years |
TSV, Zimmer dental |
Prosthetic stability, MBL |
ITSFPD is better in terms of MBL Clinical outcome is same |
|
7 |
Mostafa27 et al 2015 |
NRCT with equal compare group |
Egypt |
20 |
25-30 |
10 TI; 10 II Prosthesis |
2 years |
TSV, Zimmer dental |
Plaque index, probing depth, Bone level loss |
TI=II |
Table 2
Study Outcomes of included research articles and meta-analysis
Others
Plaque index – 0.63 in implant implant (II), 0.60 in tooth implant (TI) group from three studies.
Gingival index and probing depth in Bragger’s study was 0,47 and 2.56mm for implant implant (II) and 0.56 and 2 61 in tooth implant (TI group respectively
Sensory disturbance – 7 patients had some sort of sensory disturbance in mental region in Gunne’s and Olssun’s study.
Risk of bias assessment elaborated in the Figure 4.
Figure 2 shows the Relative risk less than 1 shows less chance of implant failure in ITSFPD compared to FSIS denoted by central diamond, lower confidence interval and upper confidence interval is denoted by arrow marks.
Figure 3 shows the data of mean marginal bone loss after 2 years of follow-up from rest 6 studies. ANOVA test gave the f-ratio value of 0.49412 and accordingly the p-value was 0.49. Although MBL was less in TI group but the results were not significant at p < .05.
Discussion
Prosthesis stability 3, 4, 10, 12, 24, 25, 26, 27, 28
The overall stability as observed from the review concluded with a non-significant p- value with the results compared from five authors included in the study. The range of the prosthesis failure varied up to 13%. All authors compared implant tooth supported fixed dental prosthesis (ITSFPD) and free- standing implant supported prosthesis (FSIS) for technical complications and clinical success. Five studies conducted by Gunne et al,3 Bragger et al,1 Lindh et al, 10 Acka et al, 4 Olsson et al28 compared prosthetic stability between implant tooth supported fixed dental prosthesis and free-standing implant supported fixed dental prosthesis. It was observed that in different studies around 11 prostheses were lost in FSIS, whereas 9 prostheses were lost in ITSFDP. In relation with clinical success the highest failure was recorded in the study3 where four implant tooth supported fixed dental prosthesis were lost over a span of 3 years. The study26 demonstrated no significant difference between the prognosis of ITSFDP and FSIS. In the study conducted by Mostafa et al27 observed abutment screw loosening in tooth- implant supported fixed dental prosthesis.
Although the p value wasn’t found to be significant, but it can be concluded with the included studies, that tooth implant supported prostheses can serve as a viable treatment option, since the range of prostheses failure according to the meta analyses is lesser than implant implant prostheses.
Implant failure: 3, 4, 10, 12, 24, 25, 26, 27, 28
The overall implant failure rate for the current systematic review from all the included articles ranges up to 11.5% over the span of 1992-2021. The highest failure rate was encountered where the observed study time by Olsson et al 28 was for five years. The article comprised of 23 patients, with Kennedy’s Class I dentulous situation in the mandibular arch, opposed to a maxillary complete denture. A total of 69 implants were placed of which, total of 8 implants were lost, with a cumulative failure rate of 12 %. This study concluded the better prognosis of type 2- tooth- implant supported prosthesis over, type 1- implant -implant supported prosthesis. On the other hand, the studies conducted by Lindh et al, 10 Mostafa et al 27 reported 3- 4% of overall failure.
There was another study done by Fobbe et al 25 that observed the overall survival of implant- tooth supported prosthesis to be better over an observation span of 11.2 years.
The several studies included for the analyses showed better success rate in tooth–implant supported prostheses for implant survival within the specified follow up period.
Marginal bone loss 3, 4, 10, 12, 24, 25, 26, 27, 28
Four studies conducted by Gunne et al, 3 Acka et al,4 Lindh et al, 10 Hosny et al, 26 compared marginal bone loss (MBL) between implant tooth supported and free- standing implant supported fixed dental prosthesis. Taking into consideration of marginal bone loss, the metanalysis evaluated 4 studies depicting the same.
The study by Gunne et al3 found the MBL in ITSFPD, 0.3-0.1 mm while in FSIS- 0.7-0.2. However very marginal difference was found in support of ITSFPD when compared to FSIS. All authors compared implant tooth supported and free-standing implant supported fixed dental prosthesis for technical complications and clinical success. It was observed that in different studies around 11 prostheses were lost in ITSFDP, whereas 9 prostheses were lost in FSIS. In relation with clinical success, marginal bone loss (MBL) was assessed in various studies. It was found that 0.18 to 0.7mm MBL was reported in patients with ITSFPD, whereas in cases with FSIS, the MBL was observed to be 0.09 to 0.7mm. But in relation to each study, MBL was observed to be less in ITSFDP than FSIS. Technical and clinical complications like sensory disturbance, abutment loosening, fistula formation, periimplantitis, loss of facing, loss of cementation, loss of occlusal wear; were assessed in both the groups. It was observed that cases of peri implantitis, sensory disturbance, abutment tooth fracture, abutment screw loosening was more in FSIS as compared to ITSFPD. The marginal bone loss values reported in this review after 24 months of loading, however, remain within the range for implant success.
Other complications
Five studies conducted by Gunne et al, 3 Bragger et al,1 Lindh et al,10 Acka et al,4 Olsson et al28 compared various types of complications (sensory disturbance, abutment loosening, fistula formation, Periimplantitis, loss of facing, loss of cementation, loss of occlusal wear) between Implant tooth supported and free- standing implant supported fixed partial denture prosthesis. Although the difference was elicited was not significant. Sensory disturbance of 19% was noted in the study, done by Gunne et al.3
The inclusion of only seven studies may have influenced the intervention effect, as each study only comprised of a limited number of implants and prostheses. In addition, substantial heterogeneity was noted despite the stringent selection criteria employed in this review. It is also acknowledged that implants are not independent units and that data analysis based on abutment tooth/implant rather than the participant may underestimate the outcomes and complications associated with tooth implant and implant implant supported prostheses.
In addition, the possible limitation includes that the present review attempted an exhaustive search with no language re-strictions through published and grey literature in the search for outcome comparisons which may have influenced the study outcomes.
Conclusion
Within the limitations of the current meta- analysis and systematic review.
No significant difference was observed between several studies included in the review between tooth implant and implant supported prosthesis.
Therefore, it can be suggested that, tooth implant supported prosthesis can be considered an adjunctive /alternative and viable treatment option for the replacement in cases of partially edentulism.
