1. 補綴牙科 實 證 期 刊 閱 讀 報 告 EBM-style Journal Reading
報告人：王韻涵
指導臨床教師：張佑琪醫師
日期：2016/03/04
地點：牙科部討論室

2. Clinical Scenario （臨床情境）
一位45歲男性，因蛀牙拔除右下第一大臼齒，想以植體方式復型，前來進行評估。
臨床上植體可見cement-retained 和 screw-retained 兩種不同形式的retention system，且各有其優缺點，該如何選擇?

3. Clinical Uncertainty → PICO 問題
In terms of implant survival, and prosthetic complications, which retention system is better for fixed implant-supported restorations?

4. 臨床個案的PICO Patient, problem:
Patient rehabilitated with with fixed implant-supported restorations
Intervention:
Cement-retained prostheses
Comparison:
Screw-retained prostheses
Outcome:
implant survival, prosthetic complications
Type of Question: Therapy

5. Search Terms & Strategy: （搜尋關鍵字與策略）
資料庫：PUBMED
搜尋日期：
搜尋關鍵字與隅策略：
cement versus screw retained implant

7. Best available evidence: （挑選可獲得之最佳研究證據）
Citation/s:
Evaluation of cement-retained versus screw retained implant-supported restorations for marginal bone loss: A systematic review and meta-analysis
Lead author's name :
Cleidiel Aparecido Araujo Lemos
Prostho Dent Nov 14.
Lemos CA1, de Souza Batista VE1

8. The Study: （研究效度）- 1 Inclusion criteria: Exclusion criteria:
Randomized controlled trials (RCTs), prospective and retrospective studies (included because of the shortage of RCTs).
Studies needed to have at least 10 participants
Follow-up periods of longer than 1 year
Be published in English.
Exclusion criteria:
In vitro studies, animal studies, computer simulations,case reports
No comparisons between cement- and screw-retained prostheses
Prostheses were conjugated with teeth

9. The Study: （研究效度）- 2
A comprehensive search of studies published from January 1995 to March 2015 and listed in the PubMed/MEDLINE, Embase, Scopus and the Cochrane Library databases was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.
The meta-analysis was based on the Mantel-Haenszel and inverse variance methods.
進行醫藥評估的系統性回顧後，作者於撰寫文獻搜尋與選擇 結果時必須依據 1996 年所制定的QUOROM (QUality Of Reporting Of Meta-analysis) 內容書寫。這個依據已經在 2009 年 7 月有了重大更新， 最新的依據簡稱為PRISMA （Preferred Reporting Items for Systematic Reviews and Meta-analysis）聲明1 。

10. The Study: （研究效度）- 3 本篇文獻的PICO (T)
Patient / Problem
What is the best retention system
for fixed implant-supported restorations
Intervention
Cement-retained prostheses
Comparison
Screw-retained prostheses
Outcome
Primary outcome --- marginal bone loss around implant
Secondary outcomes --- survival rates of the implants, the
prosthetic complications, and the marginal plaque index
Time
The mean follow-up was 65.4 months
(range: months)

11. The Study: （研究效度）- 4 Types of outcome measures
Dental implant and prosthetic failures were the dichotomous outcome measures evaluated for risk ratio (RR).
Marginal bone loss was the continuous outcome measure evaluated for mean differences (MD) .
Both with the corresponding 95% confidence intervals (CI).

12. The Evidence: （研究重要結果）- 1
The kappa interinvestigator agreement for selected articles showed a high level of agreement.
PubMed/MEDLINE (kappa value=0.91),
Scopus (kappa value=0.87),
Embase (kappa value=0.74),
Cochrane Library (kappa value=1.00)

13. A total of 8989 implants /2139 participants mean age of 47.14 yrs
20 studies
A total of 8989 implants /2139 participants
mean age of yrs
mean follow-up was 65.4 months
(range: months)

14. The Evidence: （研究重要結果）- 2
ITI Straumann was the most commonly used implant system.
The mandibular arch was the most prevalent for implant placement, most implants were placed in posterior regions of the mouth, and single crowns were the type of prosthesis most studies evaluated.

15. The Evidence: （研究重要結果）- 2
Marginal bone loss 6 studies
Marginal bone loss was significantly less with cement-retained prostheses than with screwretained prostheses
( P=.04; MD: −0.19; 95% CI: −0.37 to −0.01)

16. The Evidence: （研究重要結果）- 3
Survival rate 16 studies
Total 16 篇 studies 進行分析。總共有 (72+26= 98) 個 implant failure。其中有8個 study在follow up期間沒有任何形式的implant failure。
Quantitative analysis showed statistically significant higher survival rates for cement-retained implant-supported restorations.
(P=.01; RR: 0.49; 95% CI: 0.28 to 0.85)

17. The Evidence: （研究重要結果）- 4
Loosened screws was the most prevalent complication in both of the retention systems.
Although loosened screws can be easily tightened, some complications such as ceramic fractures, which tend to occur in the posterior region, are not easily reparable.
Debonding is a complication reported for cement-retained retention.

18. The Evidence: （研究重要結果）- 4
Prosthetic complications 16 studies
Quantitative analysis of complication rates showed statistically significant differences that favored cement-retained prostheses over
screw-retained prostheses (P=.04; RR: 0.52; 95% CI: 0.28 to 0.98)
Quantitative analysis of complication rates showed statistically significant differences that favored cement retained prostheses. (P=.04; RR: 0.52; 95% CI: 0.28 to 0.98)

19. The Evidence: （研究重要結果）- 5
Plaque index 2 studies
Two studies32,36 evaluated the plaque index.
Quantitative analysis found no significant differences between retention systems in relation to the mean plaque index.
(P=.58; MD: 0.13; 95% CI: −0.32 to 0.57)
Quantitative analysis found no significant differences between retention systems in relation to the mean plaque index.
(P=.58; MD: 0.13; 95% CI: −0.32 to 0.57)

20. Comment & Discussion: -1
The current meta-analysis indicated that cement-retained, fixed implant-supported restorations showed less marginal bone loss during the follow-up period (range: months).
However, the small difference between the mean values may not show clinical significance. --- > Do not compromise the use of screw-retained prostheses.
( P=.04; MD: −0.19; 95% CI: −0.37 to −0.01)
當前的meta-analysis顯示cement-retained, fixed implant-supported restorations 有較少的marginal bone loss 。
然而平均差異非常微小MD: −0.19mm，因此可能不具有臨床意義。故不需要因此compromise the use of screw-retained prostheses.

21. Comment & Discussion: -2
The rates of implant survival compared favorably with cement-retained prostheses.
Nevertheless, high survival rates of implants were observed for both retention systems.
1 study showed a higher weight (58.8%) of contribution in the meta-analysis of survival rates of the implants.
(greater number of cement-retained restorations --- can be considered a bias)
Thus, well-designed studies need to be performed to offer more reliable data.
研究顯示cement-retained有較高的implant survival rate，survival rate可能受到marginal bone loss and complications (如loosened screws)的影響，
which may increase implant fractures, especially in the posterior region.
Some limitations may have affected this result: analyses were not performed in a single arch or region, and factors such as high masticatory force, and a cantilever bridge can affect implant loss.

22. Comment & Discussion: -3
Complication rates ---
compared favorably with cement-retained prostheses.
Screw-retained single- and multiple-unit restorations had more technical complications than cement-retained restorations.
Gotfredsen K; , Wiskott A on behalf of Working Group 4. Consensus
reportdreconstructions on implants. The Third EAO Consensus Conference
2012. Clin Oral Implants Res 2012;23:
為了改善 passive fit 問題而增加greater preload exerted 可能可以解釋higher frequency of abutment screw loosening。
另外，像是後牙區只有single crown , cantilever extensions, prosthesis misfit, and the screw diameter being smaller than the other components of the implants 都是可能導致screw loosening的因素。改善screw的設計或是合金成分可能可以降低screw loosening發生的機會。
再者，透過仔細的咬合調整，避免側方及前突Contact 。
Non-passive fit 會增加施予implant的壓力，增加材料疲勞因而增加screw fracture的機會。
對於cement retained 而言，則較容易達到passivity。
Gotfredsen K et.al The Third EAO Consensus Conference 2012.
Sailer et.al

23. Comment & Discussion: -4
Results of the present review should be interpreted with caution because of the few RCTs (3/20) included in the analysis.
Further RCTs with longer follow-up periods are recommended to investigate the different retention systems.

24. Systemic review and meta-analysis of 20 studies, with 3 RCTS and others are prospective and retrospective studies
Level of Evidence: 2

25. Clinical bottom line 臨床決策底線
回到臨床個案情境
Clinical bottom line 臨床決策底線
Cement-retained, fixed implant supported restorations showed less marginal bone loss. However, the small difference between the mean values may not show clinical significance.
The rates of prosthetic complication and implant survival also compared favorably with cement-retained prostheses.
Results of previous studies that have compared retention systems of fixed implant-supported restorations suggest that cement-retained rather
than screw-retained prostheses lead to better preservation of bone tissue around the implant.
Consequently, the rates of implant survival are higher and the rates of complications are lower.
證據等級2a , 建議等級B

26. References
Lee A, Okayasu K, Wang HL. Screw- versus cement retained  implant restorations: current concepts. Implant Dent Feb;19(1):8-15.
Gotfredsen K; , Wiskott A on behalf of Working Group 4. Consensus reportdreconstructions on implants. The Third EAO Consensus Conference Clin Oral Implants Res 2012;23:

27. Kill or Update By（下次更新日期）:
結 論
（臨床底線的精要敘述）
Cement-retained rather than screw-retained fixed prostheses showed less marginal bone loss, higher implant survival rates, and lower complications rates, but may not show clinical significance.
Kill or Update By（下次更新日期）:
105 年 02 月 28 日

28. Thanks for your listening!
END
Thanks for your listening!