1http://dx.doi.org/10.20396/bjos.v21i00.8664977 Volume 21 2022 e224977 Original Article 1 Departement of Periodontogy, University of Padjadjaran, Indonésia. Corresponding author: Puspa Puspita Lasminingrum Adress: Bandung, West Java, Indonesia E-mail adress: puspa16002@mail. unpad.ac.id Editor: Dr Altair A. Del Bel Cury Received: March 15, 2021 Accepted: June 30, 2021 The assessment of periimplant soft tissue condition with morse taper abutment connection: a rapid review Puspa Puspita Lasminingrum1,* , Aldilla Miranda1 , Dyah Nindita Carolina1 , Prajna Metta1 Aim: This study aims to evaluate the clinical assessment results of periimplant soft tissue with morse taper (internal abutment connection). Methods: The study was conducted using a rapid review by searching the articles from PubMed NCBI and Cochrane by using keywords. All articles were selected by the year, duplication, title, abstract, full-text, and finally, all selected articles were processed for final review. Following clinical parameters were included; Periimplant Probing Pocket Depth (PPD), Plaque Score (PS), modified Plaque Index (mPI), Mucosal Thickness (MTh), Gingival Height (GH), periimplant mucosal zenith, Pink Esthetic Score (PES), Bleeding On Probing (BOP), Sulcus Bleeding Index (SBI), and modified Gingival Index (mGI). Results: 9 selected articles were obtained from the initial literature searching count of 70 articles. The overall samples included 326 morse taper implants. Based on the evaluation, 3 out of 4 articles reported pocket depth < 4 mm, no bleeding was reported in 2 out of 4 articles. 4 out of 4 articles reported low plaque accumulation, low soft tissue recession was reported in 3 out of 3 articles, and 4 out of 4 articles reported acceptable PES values. Conclusion: The evaluations indicate that the morse taper (internal abutment connection) has favorable assessment results based on various clinical parameters. Keywords: Dental implant-abutment design. Soft tissue injuries. Dental abutments. Dental implants. Gingiva. Mouth mucosa. https://orcid.org/0000-0002-8771-3649 https://orcid.org/0000-0003-1474-0053 https://orcid.org/0000-0003-0208-1353 https://orcid.org/0000-0001-8508-1919 2 Lasminingrum et al. Introduction Dental implants have been widely used for the replacement of missing teeth1. The survival rate of dental implant treatment for five years reached 96.3%2. However, this treatment still caused several complications such as; technical complications or screw loosening 8.8%; soft tissue complications 7.1%; marginal bone loss 5.2%; and aesthetic complications 7.1%2. The implant system can be differentiated based on the material used in dental implants, surface topography, morphology, and geometry of the abutment connec- tion3. The geometry of the abutment connection influences the incidence of screw loosening and may play a crucial role of the bacterial composition in the neck area of the implant4. The formation of microgap due to bacterial leakage on the abutment connection causes microleakage to occur5. Microleakage allows penetration and accumulation of bacteria through the microgap which leads the periimplant soft tis- sue inflammation5. Therefore, this can affect the stability of marginal bone, periim- plant soft tissue, and aesthetics condition5. Basically, the geometry of the abutment connection is divided into external con- nection and internal connection1. External connection was first implemented in the Branemark implant system and has a hexagonal structure3,6. Internal connection has several variants, including internal hexagon and morse taper7. Morse taper abutment connection that was placed in the anterior maxilla had the lowest global annual failure rate (0.2%)8. This design can reduce microgap and micromovement formation due to its ability to resist leakage9. Therefore, better load distribution on the abutment connection obtained and minimal marginal bone loss observed with morse taper9. The stability of periimplant soft tissue is one of the key aspects of successful dental implant treatment because it provides sealing ability and stability of the marginal bone, prevents penetration of oral microorganisms, and enables good aesthetic results10. A considerable amount of literature from NCBI PubMed and Cochrane databases regarding morse taper internal abutment connection have been pub- lished. However, no previous study has been conducted using a rapid review method for evaluating the periimplant soft tissue. Based on the explanation that has been presented, this paper aims to systematically evaluate the clinical assesment results of periimplant soft tissue using morse taper (internal abutment connection) with the rapid review method. Material and Methods This rapid review was performed according to the PRISMA (Preferred Report- ing Items for Systematic Reviews and Meta-analyses) statement (Figure 1)11,12. Selected articles were English language articles between 2009-2019 that dis- cussed morse taper and the clinical assesment result of periimplant soft tissue with a minimum follow-up period of 12 months. Non full -text article and narrative review were excluded. 3 Lasminingrum et al. An electronic search through PubMed NCBI and Cochrane was conducted using the Boolean Operators method with keywords “(((((morse taper[Title/Abstract]) OR con- ical interface[Title/Abstract]) OR conical connection[Title/Abstract])) AND (((periim- plant[Title/Abstract]) OR soft tissue[Title/Abstract])) AND clinical[Title/Abstract]”. All articles were selected by the year, duplication, title, abstract, full-text, and finally, all articles were obtained and analyzed using the thematic analysis method. Following data were assessed: Periimplant Probing Pocket Depth (PPD), Bleeding On Probing (BOP), Sulcus Bleeding Index (SBI), modified Gingival Index (mGI), modified Plaque Index (mPI), Plaque Score (PS), Mucosal Thickness (MTh), Gingival Height (GH), periimplant mucosal zenith, and Pink Esthetic Score (PES). Levels of evidence were identified using the Strength of Recommendation Taxonomy (SORT). Results Through the literature searching, 70 articles were identified, selected by the year, duplication, title, and abstract. Finally, 9 full-text articles matched the inclusion criteria and were processed for the final review (Figure 1)13-21. Five articles were randomized controlled trials (SORT level of evidence-1)13,15,16,19,20. Three articles were prospective cohort studies (SORT level of evidence-2)14,17,18. One case series article (SORT level of evidence-3)18. The overall samples included 326 morse taper connection implants (MT); 151 non-morse taper internal connection implants (NMTI); and 69 non-morse taper external connection implants (NMTE)13-21. Table 2 presents the results of clinical periimplant soft tissue assessment parameters obtained from selected articles. Figure 1. Flowchart of the study selection process Id en fic ic at io n Sc re en in g El ig ib ili ty In cl ud ed Records identified through Databasa searching (n = 70) Records selected for the year of publication (n = 69) Records after duplicates removed (n = 61) Records screened for title and abstract (n = 31) Full-text articles assessed for eligibility (n = 9) Articles Included in the review (n = 9) Record excluded by title and abstract (n = 30) Articles excluded for full-text analysis (n = 22) 4 Lasminingrum et al. Ta bl e 1. C lin ic al P er iim pl an t S of t T is su e A ss es sm en t P ar am et er s fr om S el ec te d A rt ic le s A ut ho r (y ea r) S tu dy de si gn Fo llo w -u p pe ri od N um be r of S am pl es / C on ne ct io n ty pe C lin ic al P ar am et er s R es ul ts R em ar ks C oo pe r, et a l.1 3 (2 01 9) R an do m iz ed co nt ro lle d tr ia l 3 ye ar s 79 im pl an ts : Ex pe rim en ta l • M T: 4 5 (O ss eo sp ee d) C on tr ol • N M TI : 3 4 (N ob el Sp ee dy ) 1. P P D 2. P er iim pl an t m uc os al z en ith re ce ss io n 1. P P D ≥ 4 m m b uc ca l a sp ec t: • M T 7% • N M TI 1 8% P P D ≥ 4 m m li ng ua l a sp ec t: • M T 2% • N M TI 2 4% 2. P er iim pl an t m uc os al z en ith re ce ss io n ≤ 5 m m : • M T 80 % • N M TI 6 1% 1. P P D ≥ 4 m m b uc ca l a nd li ng ua l as pe ct th e le as t o cc ur re d in M T 2. P er iim pl an t m uc os al z en ith re ce ss io n ≤ 5 m m m os tly oc cu rr ed in M T P es so a, e t a l.1 5 (2 01 7) R an do m iz ed co nt ro lle d tr ia l 1 ye ar 48 Im pl an ts : Ex pe rim en ta l • M T: 2 4 (U N I-T IT E) C on tr ol • N M TE : 2 4 (U N I-T IT E) 1. P P D 2. M Th 3. m G I 1. A ve ra ge P P D : • M T 1. 36 ± 0 .7 m m • M TE 1 .5 7 ± 0. 9 m m 2. A ve ra ge M Th : • M T 2. 27 ± 0 .8 5 m m • N M TE 2 .1 6 ± 0. 94 m m 3. m G I • V er y lo w in b ot h ty pe s 1. L ow er p oc ke t d ep th a nd m uc os al ap pe ar an ce w er e fo un d w ith M T 2. N o si gn ifi ca nt d iff er en ce fo r po ck et d ep th a nd m uc os al th ic kn es s in b ot h ty pe s 3. V er y lo w b le ed in g in de x fo un d in bo th ty pe s B ar w ac z, e t a l.3 6 (2 01 6) R an do m iz ed co nt ro lle d tr ia l 3 ye ar s 97 im pl an ts : Ex pe rim en ta l • M T: 4 8 (O ss eo sp ee d) C on tr ol • N M TI : 4 9 (N ob el sp ee dy ) 1. P ES 1. A ve ra ge P ES : • M T 10 .4 • N M TI 1 0. 0 1. B ot h ty pe s sh ow ed fa vo ra bl e P ES v al ue s w ith n o si gn ifi ca nt di ff er en ce M cG ui re , e t a l.1 9 (2 01 5) R an do m iz ed co nt ro lle d tr ia l 1 ye ar 8 im pl an ts : Ex pe rim en ta l • M T: 4 (O ss eo sp ee d) C on tr ol • N M TI : 4 (N ob el sp ee dy ) 1. P ES 1. A ve ra ge P ES v al ue s: • M T 11 .3 5 • N M TI 1 1. 55 1. B ot h ty pe s sh ow ed fa vo ra bl e P ES v al ue s w ith n o si gn ifi ca nt di ff er en ce C on tin ue 5 Lasminingrum et al. P oz zi e t a l.2 0 (2 01 4) R an do m iz ed co nt ro lle d tr ia l 3 ye ar s 68 im pl an ts : Ex pe rim en ta l • M T: 3 4 (N ob el a ct iv e) C on tr ol • N M TE : 3 4 (N ob el sp ee dy ) 1. S B I 2. P S 1. S B I f ou nd in 1 N M T 2. P S fo un d in 1 M T an d 1 N M TE (y ea r 1 ) 1. N o si gn ifi ca nt d iff er en ce in th e as se ss m en t o f S B I a nd P S 2. N o bl ee di ng in a ll so ft ti ss ue su rf ac es w ith M T 3. P la qu e ac cu m ul at io n w as fo un d in 1 im pl an ts w ith M T an d 1 im pl an t w ith N M TE a ft er 1 y ea r in fu nc tio n H ey de ck e, e t a l.1 4 (2 01 9) P ro sp ec tiv e C oh or t 3 ye ar s M T: 9 9 (N ob el R ep la ce C on ic al C on ne ct io n) 1. B O P 2. m P I 3. P ES 1. N o B O P in 8 0. 7% s of t t is su e su rf ac es 2. N o pl aq ue w as o bs er ve d on 6 5. 9% im pl an t si te s fr om m P I a ss es sm en t 3. A ve ra ge P ES : 9 .8 7 ± 2. 19 1. N o bl ee di ng w as fo un d in 8 0. 7% pe rii m pl an t s of t t is su e su rf ac es 2. N o pl aq ue a cc um ul at io n w as fo un d in 6 5. 9% im pl an t s ite s 3. A cc ep ta bl e P ES re su lt C os yn , e t a l.1 8 (2 01 6) P ro sp ec tiv e C as e Se rie s 5 ye ar s M T: 1 7 (N ob el A ct iv e) 1. P P D 2. B O P 3. P S 4. P ES 1. A ve ra ge P P D : 3 .1 m m 2. A ve ra ge P S: 1 5% , 3. A ve ra ge B O P : 3 2% 4. A ve ra ge P ES : • 12 .1 5 (1 y ea r) • 11 .1 8 (5 y ea r) 1. F av or ab le P P D a nd P S re su lts 2. B le ed in g w as fo un d in B O P as se ss m en t 3. S ig ni fic an t P ES v al ue re du ct io n (- 0. 97 ) w ith in 5 y ea rs fo llo w -u p G ul te ki n, e t a l.2 1 (2 01 3) P ro sp ec tiv e C oh or t 15 m on th s 93 im pl an ts : Ex pe rim en ta l • M T: 4 3 (N ob el A ct iv e) C on tr ol • N M TI : 5 3 (N ob el R ep la ce Ta pe re d G ro ov y) 1. P P D 2. m P I 1. A ve ra ge P P D v al ue s: • M T 2. 6 ± 0. 46 m m • N M TI 3 .3 3 ± 0. 51 m m 2. A ve ra ge m P I v al ue s: • M T 0. 64 ± 0 .2 8 • N M TI 0 .6 1 ± 0. 36 1. S ig ni fic an t d iff er en ce o f t he av er ag es o f p oc ke t d ep th w as fo un d, th e lo w es t p oc ke t d ep th ob se rv ed in M T 2. N o si gn ifi ca nt p la qu e in de x va lu es d iff er en ce . A cc ep ta bl e re su lts w er e re po rt ed in b ot h ty pe s K am in ak a, e t a l.1 7 (2 01 5) P ro sp ec tiv e C oh or t 1 ye ar 22 im pl an ts : Ex pe rim en ta l • M T: 1 2 (N ob el A ct iv e) C on tr ol • N M TE : 1 1 (N ob el Sp ee dy G ro ov y) • N M TI : 1 1 (N ob el R ep la ce ) 1. G H re du ct io n (t he m ea su re m en t fr om th e im pl an t pl at fo rm to th e m ar gi na l s of t tis su e le ve l ) us in g C B C T 1. Δ G H v al ue s: • M T 0. 06 ± 0 .1 0 m m • N M TE 0 .3 9 ± 0. 19 m m • N M TI 0 .2 8 ± 0. 30 m m 1. S ig ni fic an t d iff er en ce s of G H re du ct io n va lu es w er e ob se rv ed , lo w es t r ed uc tio n w as fo un d in M T C on tin ua tio n 6 Lasminingrum et al. Favorable PPD results with morse taper were reported in 3 out of 4 articles (75%). Cooper et al.13 (2019) found PPD ≥ 4 mm the least occurred with morse taper. Three studies reported the PPD averages of 1.36 ± 0.7 mm, 2.6 ± 0.46 mm, and 3.1 mm15,18,21. No bleeding presence on most of the periimplant soft tissue surfaces was reported in 2 out of 4 articles (50%). Pessoa et al.15 (2017) stated low mGI Score in the evaluated region with morse taper. Heydecke et al.14 (2019) observed no bleeding occurred in 80.7% of surfaces and another study by Pozzi et al.20 (2014) reported no bleeding found on all surfaces. On the contrary, as stated by Cosyn et al.18 (2016) bleeding was found in 32% of periimplant soft tissue surfaces. Low plaque accumulation was reported in 4 out of 4 articles (100%). Pozzi et al.20 (2014) found a slight plaque accumulation in one morse taper implant after one year in function. Cosyn et al.18 (2016) stated that the PS was on average of 15% after 5 years follow-up period. Heyecke et al.14 (2015) found no plaque accumulation in 66.9% implants. A study by Gultekin et al.21 (2013) stated the mean mPI value was 0.64 ± 0.28 after 12 months follow-up period. Low soft tissue recession was reported in 3 out of 3 articles (100%). Kaminaka et al.17 (2015) stated that among other designs, morse taper showed the lowest gin- gival height reduction, which was - 0.06 ± 0.10 mm. Cooper et al.13 (2019) reported periimplant mucosal zenith reduction of less than 5 mm found in 80% of implants with morse taper. Pessoa et al.15 (2017) reported the average MTh value of 2.27 ± 0.85 mm after implant placement. Acceptable PES values were reported in 4 out of 4 articles (100%). Two studies that assessed PES in implants with morse taper internal connection and non-morse taper internal connection, stated that there was no significant difference and both types of abutment connection had equally good PES values13,16. Other authors reported PES value with the averages of 9.87 ± 2.19 and 11.1814,18. Discussion The examinations of PPD and BOP have been considered as the assessment to define a successful dental implant treatment22-24. Takei and Carranza4 (2019) stated that pocket depth around 3 mm without any presence of bleeding on all surfaces could be identified as a healthy periimplant soft tissue condition. In this review, several studies showed the average of PPD ≤ 3.1 mm15,18,21 Low percentages of BOP and SBI were also found14,20. This result might be explained by the concept of morse taper connection, which is a particular kind of internal abutment connection with a matching conical or taper shape and an equal angle (5-16° of conicity) between the wall of abutment and the implant3. This creates an intimate contact and a significant amount of mechanical friction lock- ing. Hence, this design can stabilize under static load, eliminates microgap below dynamic load, and prevents micromovement14. Recent study reported that no type of abutment connection could 100% prevent microleakage25. However, the microgap formed in morse taper (2-3 μm) was smaller than in external connection (10 μm), which pointed out that morse taper had a better bacterial seal compared to the exter- nal connection6,26-30. Bacterial contamination through microgap causes an inflamma- 7 Lasminingrum et al. tory reaction in the periimplant soft tissue and triggers an osteoclastic process that may precipitate on marginal bone resorption around the implant5,15,31. Gingival reces- sion due to bone resorption caused by the absence of supracrestal connective tissue as established in periodontal tissue leads the periimplant soft tissue to thoroughly rely on the supporting marginal bone4. This view is supported by the recent systematic review by Caricasulo et al.9 (2018) who stated that the least marginal bone loss was found in the internal connection, especially in the morse taper. Favourable periimplant soft tissue assessment results in this review are likely to be related to the optimal support from the marginal bone due to low bone resorp- tion13,15,17,20. Consequently, a healthy periimplant soft tissue condition and a satisfac- tory aesthetic result will be obtained15. This is consistent with that of Kaminaka et al.17 (2015) who concluded that morse taper was more effective in preserving the stability of the periimplant hard and soft tissue. Another factor that might influence this con- dition is the presence of platform switch, which is a concept of the placement of nar- rower diameter abutment. Therefore, if the bacterial contamination on the microgap persists; a certain distance between the microgap and the neck of the implant that attached to the marginal bone will be maintained15. Hence, minimal marginal bone resorption obtained and adequate biological width will be established15. This accords with another study by Macedo et al.26 (2016), that reported low marginal bone resorp- tion and wide biological width observed in apical and lateral directions with morse taper and platform switch abutment. In this article, all types of abutment connections reported acceptable PES results13,14,16,18. However, only some appeared to be in healthy periimplant soft tissue conditions and some of the results showed the presence of bleeding on probing and pocket depth ≥ 4 mm which may lead to periimplant mucositis and periimplantitis20,21. According to some studies, there were several factors other than the variation of the implant abut- ment connection that may influence the PES results such as, the presence of implant thread, the surface roughness of the implant neck, tissue biotype, and the experience of the clinicians15,16. Dani et al.32 (2018) found that higher soft tissue recession was observed with inexperienced clinicians after 3 years following implant placement. Time may also play as a contributing factor to this outcome. Cosyn et al.18 (2016) stated that recession more than 1 mm was found in 3 out of 17 implants after 5 years following implant placement, which caused a significant change in PES results. This finding seems to be consistent with a study by Pozzi et al.20 (2014) which stated that statistically significant results may be obtained by the longer research period. High plaque accumulation within the study period may increase the risk of periimplant disease33. likewise, Dhir34 (2013) and Prado et al.25 (2016) stated that bacterial contam- ination might exist in the implant abutment connection causing fluid leakage into the microgap and reduce the mechanical friction between surfaces. Therefore, this could affect the periimplant soft and hard tissue condition25,34. Better sealing capability from morse taper can reduce microgap and prevent any leakage6. This view is supported by low plaque accumulation results around the periimplant soft tissue surfaces with morse taper in this review14,18,35. In contrast to earlier findings, recent study have failed to demonstrate significant changes of plaque index results between morse taper (0.64 ± 0.28) and internal connection (0.61 ± 0.36)21. Mishra et al.6 (2017) stated that 8 Lasminingrum et al. implant abutment connection plays an important role in preventing bacterial leakage. However, infiltration of inflammatory substances may occur regardless of the amount of plaque accumulation6. A possible factor that may increase the formation of bio- films other than the type of connection is the implant surface roughness ≥ 0.2 µm34. A limitation of this study is that only a few articles have assessed the role of implant abutment connection towards periimplant soft tissue condition in 5 years follow-up period with comprehensive assessment and randomized control trial method. Another source of uncertainty is the varied specifications of morse taper that came from sev- eral implant systems. Therefore, it is difficult to determine which factors have a sig- nificant impact on the assessment results. Future researches on the current topic are therefore suggested. In conclusion, the results of this evaluation indicate that the morse taper (internal abutment connection) has favorable assessment results based on various clinical parameters such as; PPD; PS; mPI; MTh; GH; periimplant mucosal zenith; and PES. The low percentage of bleeding around periimplant soft tissue surfaces were reported from the assessment of BOP, SBI, and mGI examinations. Acknowledgment The authors appreciate the financial support for this review provided by LPDP, Ministry of Finance, Republic of Indonesia. References 1. Goiato MC, Pellizzer EP, da Silva EVF, Bonatto L da R, dos Santos DM. 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