Interventions for replacing missing teeth: 1- versus 2-stage implant placement

 

Abstract

Background

Implants may be placed penetrating the oral mucosa (1-stage procedure) or can be completely buried under the oral mucosa (2-stage procedure) during the healing phase of the bone at the implant surface. With a 2-stage procedure the risk of having unwanted loading onto the implants is minimized, but a second minor surgical intervention is needed to connect the healing abutments and more time is needed prior to start the prosthetic phase because of the wound-healing period required in relation to the second surgical intervention.

Objectives

To evaluate whether a 1-stage implant placement procedure is as effective as a 2-stage procedure.

Search methods

The Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and EMBASE were searched. Handsearching included several dental journals. Authors of all identified trials, an Internet discussion group and 55 dental implant manufacturers were contacted to find unpublished randomised controlled trials (RCTs). The last electronic search was conducted on 21 January 2009.

Selection criteria

All RCTs of osseointegrated dental implants comparing the same dental implants placed according to 1- versus 2-stage procedures with a minimum follow up of 6 months after loading. Outcome measures were: prosthesis failures, implant failures, marginal bone level changes on intraoral radiographs, patient preference including aesthetics, aesthetics evaluated by dentists, and complications.

Data collection and analysis

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two review authors. Authors were contacted for missing information. Results were expressed as random-effects models using mean differences for continuous outcomes and risk ratios for dichotomous outcomes with 95% confidence intervals.

Main results

Five RCTs were identified and included reporting data on 239 patients in total. On a patient, rather than per implant basis, the meta-analyses showed no statistically significant differences for prosthesis and implant failures, though trends, especially in fully edentulous patients, favoured 2-stage (submerged) implants.

Authors' conclusions

The number of patients included in the trials was too small to draw definitive conclusions. The 1-stage approach might be preferable in partially edentulous patients since it avoids one surgical intervention and shortens treatment times, while a 2-stage submerged approach could be indicated when an implant has not obtained an optimal primary stability or when barriers are used for guided tissue regeneration, or when it is expected that removable temporary prostheses could transmit excessive forces on the penetrating abutments especially in fully edentulous patients.

 

Plain language summary

Interventions for replacing missing teeth: 1- versus 2-stage implant placement

Dental implants can be successful either if placed through the oral mucosa, sticking through the gums (1-stage procedure) or if completely buried under the soft tissues (2-stage procedure) to heal load-free for a few months. However, one additional minor surgical intervention is needed, if a 2-stage procedure is used, to allow the connection of the buried implants with the transgingival component which will hold the prosthesis in place.
The review found some evidence from five studies with 239 patients that 1- or 2-stage implant placement may have similar outcomes, though in patients with no teeth trends suggested more implant failures for those implants sticking through the gum. More research is needed to answer this question in a definitive way, but it appears possible to place dental implants following a 1-stage procedure (i.e. the implants are sticking through the gums during the bone healing period). The advantages of the 1-stage procedure are: (1) one minor surgical intervention can be avoided, and (2) the treatment time can be shortened, since it is not needed to wait for the healing/stabilization of the soft tissues after the second surgical intervention. Nevertheless there are situations when a 2-stage procedure could be preferable, for instance when a not optimal implant stability is achieved at implant placement or when there is the risk that the provisional denture transmits excessive forces to the portion of the implants sticking through the gums.

 

摘要

背景

取代缺失牙齒的介入性治療：一階段及二階段之植牙

植體在骨頭與植體表面之癒合期，可為穿透口腔黏膜(一階段術式)或完全埋在口腔黏膜之下(二階段術式)。在二階段術式中，對植體之多餘負荷力可被減至最低，但需再一次小手術介入以連接癒合帽(healing abutments)。因為多了這次手術的癒合期，在贗復期開始前會等更多時間。

目標

評估一階段植牙術式是否與二階段術式效果相當。

搜尋策略

搜尋The Cochrane Oral Health Group's Trials Register、The Cochrane Central Register of Controlled Trials、MEDLINE和EMBASE。手動搜尋一些牙科期刊。連絡所有已知試驗的作者、一個網際網路討論族群、以及55家牙科植體廠商，以找出未發表的隨機對照試驗(RCTs)。最後一次電子搜尋為2007年1月15日。

選擇標準

所有比較同種兩件式(2piece)骨整合性牙根形態(rootform)之牙科植體，以一階段及二階段術式為題，負荷(loading)後追蹤6個月以上之隨機對照試驗皆被收納進來。結果測量包括:贗復失敗、口內放射線影像之邊緣骨(marginal bone)高度、患者之喜好包括美觀、牙醫師評估之美觀性、以及併發症。

資料收集與分析

篩選合適的研究，兩位回顧之作者分別以完全相同的方法評估試驗的方法學品質並摘錄資料。會連絡作者，詢問是否有遺漏的資料。在結果方面是以隨機效果模式(randomeffects models)表現，連續性的預後結果是用平均值差，二分的(dichotomous)預後結果是用風險比(risk ratios)，95%信賴區間(CIs)。異質性的研究包括了臨床及方法學的因素。

主要結論

找到三個隨機對照試驗，其中兩個試驗，包括了45位患者，被收納進來。以患者而非每個植體為基礎分析，無統計上顯著之差異。

作者結論

試驗中的患者人數過少，無法得出可信的結論，但也顯示出兩種術式並無臨床上的顯著差異。若這些初步的結果有更強有力的試驗證實，一階段的術式可能會較佳，因其避免了一次小手術介入，且縮短了提供最終復形的等待時間。但一階段術式有其特定的適用情形，如一開始的植體穩定性不理想、或合併使用再生膜時，二階段的術式則較理想。

翻譯人

本摘要由臺灣大學附設醫院林威妮翻譯。

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌。

總結

牙科植體在穿通口腔黏膜與牙齦(一階段術式)、或完全埋於軟組織下(二階段術式)，在無負荷狀態下癒合數月時，都有機會成功。但在二階段術式時需要多一次小手術，連接黏膜下的植體與其上支承贗復物的穿黏膜零件(transmucosal component)。本回顧僅由兩個研究中的少數患者發現一些薄弱的證據，證明一階段或二階段植體可能有相似的結果。尚須更多研究才能更明確回答這個問題，但以一階段置放牙科植體看來是可行的(即骨癒合時植體是穿通牙齦的)。一階段術式之優勢為：(1)可避免再一次小手術；及(2)治療時間可縮短，因不用等待第二次手術後軟組織癒合/穩定的時間。但有時也有適合二階段術式的情況，如植體在植入時穩定性不理想的狀況。