Survival rate of dental implant placed using various maxillary sinus floor elevation techniques: A systematic review and meta-analysis

Abstract

Aim:

The aim of this systematic review is to evaluate the survival rate of dental implant placed using different maxillary sinus floor elevation techniques.

Setting and Design:

PRISMA guidelines were used for this systematic review and meta-analysis.

Materials and Methods:

Relevant articles were searched from Medline, PubMed, Google Scholar, ScienceDirect, and Cochrane trials. Articles published in English language were selected. Hand search was further conducted. For risk of bias, two tools were used, i.e., Cochrane tool for randomized controlled trials (RCTs) and new castle Ottawa quality assessment tool for non-RCTs.

Statistical Analysis:

For statistical meta-analysis RevMan 5.4 software was used.

Results:

Seventeen studies were finalized. All studies were included in the meta-analysis to check the implant survival rate. There is no statistical difference between direct and indirect techniques, and forest plot was derived for direct approach (P = 0.688, 95% confidence interval [CI] 0.9691) and for indirect approach (P = 0.686 and 95% CI 0.970).

Conclusion:

There is no statistically significant difference in the survival rate of implant placed using direct or indirect sinus lift approach procedures. Hence, the technique is selected as per the indications given for each direct and indirect procedure.

INTRODUCTION

The rehabilitation of missing or lost teeth by means of implant reconstruction is a predictable treatment option. Implant placement in the posterior maxilla is the most challenging. Poor bone quality and quantity are limiting factors, for which different methods have been proposed.[1,2,3]

The maxillary sinus is a pyramidal-shaped cavity in the maxilla with a volume of 12–15 ml. Its anterior border extends into the pre-molar roots or distal surface of canine roots, and the posterior border reaches the maxillary tuberosity.[4] Due to its structure and location, the maxillary sinus sometimes challenges the proper placement of the implant.[5]

Techniques used for vertical bone augmentation are direct, indirect and combination of both the techniques.[6]

Autogenous bone is the most commonly used grafting material and is considered gold standard.[7,8] SFE from a lateral window approach is most commonly used technique, which was first proposed by Tatum in 1977 and first published by Boyne and James in 1980.[1]

In comparison to SFE with a lateral window approach, the osteotome procedures are less invasive to elevate the membrane, reduces the operation time, and minimum postoperative discomfort,[10] was introduced by Summers in 1994.[7,9]

Selection of the techniques depends on the anatomy of sinus floor and lateral wall of sinus and the residual bone height (RBH). For bone height <5 mm, lateral window approach is performed and for height ≥5 mm crestal approach is performed. Hence, RBH is the deciding factor between the two methods.[11] The use of piezoelectric technique, preserves soft tissue and maintains precision and a clear surgical site without blood during bone cutting.[12] Antral membrane balloon elevation technique is a modification of bone-added osteotome sinus floor elevation technique. In this technique, antral membrane balloon elevation is carried out through the osteotomy site.[13,14,15]

Hence, various maxillary sinus lift techniques with different modifications are studied based on the availability of type and amount of bone. The aim of this systematic review is to evaluate the survival rate of implants placed with different maxillary sinus lift procedures through a meta-analysis.

MATERIALS AND METHODS

To carry out this review PRISMA guidelines and population, intervention, comparison, outcome, and study design (PICOS) structure were used to develop the search strategy.

Population, intervention, comparison, outcome, and study design framework

According to PICOS strategy, P represents patients having maxillary edentulous space in the posterior region requiring sinus floor elevation for implant placement, I represents maxillary sinus floor elevation for dental implant placement, C represents different sinus floor elevation techniques, O represents survival rate of dental implants and S represents combination of in vivo studies including randomized controlled trial (RCT), prospective, retrospective, and clinical studies.

Search strategy

An electronic literature search focusing on the purposes was performed using PubMed, Medline, Embase, and Cochrane from 1997 to 2020. The search methodology applied was combination of MeSH terms and keywords such as maxillary sinus, bone grafting, dental implants, sinus floor elevation technique, crestal sinus lift, lateral window approach, and survival rates. The searches were limited to articles written in English with an associated abstract. The studies found after hand search was also included.

Inclusion criteria

1. Prospective and retrospective studies

2. Cohort studies and randomized control trial

3. Studies on human

4. ≥6 months to ≤5 years of follow-up period

5. Studies with all different sinus floor elevation techniques.

Exclusion criteria

1. Case reports

2. Non-clinical studies

3. Animal studies

4. Inadequate data

5. Systematic reviews and meta-analyses already undertaken.

Screening for selection

The titles and abstracts were examined by two investigators. The complete text of relevant research articles was given to each investigator to review independently. The third investigator resolved the disagreement and conflict regarding the inclusion of the articles.

Risk of bias

For randomized control trials, Cochrane risk of bias tool was used and for non-randomized trials new castle Ottawa scale was used [Tables 1, 2 and Graph 1].

Table 1.

Risk of bias based on new castle Ottawa Quality Assessment Scale for cohort study

Study	Selection				Comparability	Outcome			Total quality score
	Representativeness of the exposed cohort	Selection of the nonexposed cohort	Ascertainment of exposure	Demonstration that outcome of interest was not present at start of study	Comparability of cohorts on the basis of the design or analysis controlled for confounders	Assessment of outcome	Was follow-up long enough for outcomes to occur	Adequacy of follow-up of cohorts
Zitzmann and Schiirer[16]	1	1	1	1	1	0	1	1	7
Tawil and Mawla[17]	1	0	1	1	1	0	1	1	6
Fugazzotto and Paoli[18]	0	0	1	1	1	0	1	1	5
Fugazzotto[19]	1	1	1	1	1	0	1	1	7
Leblebicioglu et al.[20]	1	0	1	1	1	0	1	1	6
Bornstein et al.[21]	1	0	1	1	1	0	1	0	5
Baldi et al.[23]	1	0	1	1	1	1	1	1	7
Mazor et al.[24]	1	0	1	1	1	0	1	1	6
Fermergård and Åstrand[25]	1	0	1	0	1	0	1	1	5
Li et al.[26]	1	0	1	1	1	0	1	1	6
Gu et al.[27]	1	0	1	1	1	1	1	1	7
Brizeula et al.[28]	1	0	1	1	1	0	1	1	6
Rao and Reddy[29]	1	0	1	1	1	0	1	1	6
Cara-Fuentes et al.[30]	1	1	1	0	1	0	1	1	6
Hussein and Hassan et al.[31]	1	1	1	1	1	0	1	1	7
Molemans et al.[32]	1	0	1	1	0	0	0	1	4

Table 2.

Determining the Quality of Studies Based on Newcastle-Ottawa Scale

Study	Selection	Comparability	Outcome	Total quality score	Quality of Study
Zitzmann and Schiirer[16]	4	1	2	7	Good
Tawil and Mawla[17]	3	1	2	6	Good
Fugazzotto and Paoli[18]	2	1	2	5	Fair
Fugazzotto[19]	4	1	2	7	Good
Leblebicioglu et al.[20]	4	1	2	6	Good
Bornstein et al.[21]	3	1	1	5	Good
Baldi et al.[23]	3	1	3	7	Good
Mazor et al.[24]	3	1	2	6	Good
Fermergård and Åstrand[25]	2	1	2	5	Fair
Li et al.[26]	3	1	2	6	Good
Gu et al.[27]	3	1	3	7	Good
Brizeula et al.[28]	3	1	2	6	Good
Rao and Reddy[29]	3	1	2	6	Good
Cara-Fuentes et al.[30]	3	1	2	6	Good
Hussein and Hassan et al.[31]	4	1	2	7	Good
Molemans et al.[32]	3	0	1	4	Good

According to Newcastle-Ottawa Scale: The study was classified as good quality (“3 or 4 stars in selection domain,” “1 or 2 stars in comparability domain,” and “2 or 3 stars in outcome/exposure domain”), fair quality (“2 stars in selection domain,” “1 or 2 stars in comparability domain,” and “2 or 3 stars in outcome/exposure domain.”) and poor (“0 or 1 star in selection domain,” “0 stars in comparability domain,” or “0 or 1 star in outcome/exposure domain)

Graph 1.

Kfir et al. 2009 randomized control trial (cochrane risk of bias tool)

Statistical analysis

The statistical analysis was carried out for included studies according to the data, on survival rate of implant placement using various sinus lift procedures through meta-analysis. For this, all the data according to inclusion criteria were taken into consideration. Mean value, P value, and heterogeneity values were obtained and the forest plots were obtained for both direct and indirect sinus lift techniques, RevMan 5.4 software was used.

RESULTS

Study selection

The search identified 895 titles on maxillary sinus lift techniques, out of which 835 were excluded on the basis of titles. Out the 60 titles selected, only 37 articles were selected on the bases of abstract. After full-text analysis, 19 articles were selected and further two more articles were excluded as per inclusion–exclusion criteria and inappropriate data. Thus, 17 articles were selected for the present systematic review [Figure 1].

Figure 1.

Flow-chart of the search strategy

Study characteristics

The 17 articles selected were published between 1998 and 2020. The research comprised nine clinical studies, five prospective, two retrospective studies, and one RCT study in the present study, a total of 337 implants were placed using direct approach and 922 implants were placed using indirect approach [Table 3].

Table 3.

Summary of all maxillary sinus floor elevation techniques in included studies

Study year	Study type	Number of patients	Number of implants (L, D and S.T)	Sinus augmentation techniques	With or W/O graft	Residual bone height	Gained bone height	Prosthetic solution	Follow up period (years)	Number of failure	Survival rate
Zitzmann and Schiirer, 1998[16]	Clinical report	30	79 L: 8.5–10 mm	20 I: Lateral approach (DI) 59 I: Osteotome (IN)	Bio-oss Bio-gide	DI: 2.3–5 mm IN: 8.8 mm	DI: 12.7 mm IN: 3.5 mm	-	2–3	3 (bio)	96% overall DI: 100% IN: 95%
Tawil and Mawla, 2001[17]	Clinical report	29	61 41 immediate 20 delayed L: 8–15 mm D: 3.75 mm	Lateral approach (DI) by elevation osteotomy	Bio-oss	Delayed: <5 mm IMM: >5 mm	-	PFM	1.5–2 years	9	93.1%
Fugazzotto and Paoli 2002[18]	Clinical report	150	167 D: 4.8 mm or 5 mm L: 10–11.5 mm	Osteotome with modified trephine (IN)	Bioabso-rbable	-	-	-	3 years	3 (bio)	97.8
Fugazzotto, 2002[19]	Clinical report	103	116 D: 3.75–4.8 mm L: 7–11 mm	Osteotome with modified trephine (IN)	-	4–5 mm	-	PFM, FPD, IRRPD	4 years	2 (bio)	98.3%
Leblebicioglu et al., 2005[20]	Clinical report	40	75 29 I: L: 11±1.7 mm 46 I: 13.5±1.06 mm	Osteotome (IN)	No graft	<9 mm or 9 mm	29 I: 3.9±1.9 mm 46 I: 2.9±1.2 mm	SC: 33 I FPD: 40 I	2 years	2 (bio)	97.3%
Bornstein et al., 2008[21]	Prospective study	56	111 TPS/SLA L: 8–12 mm D: 4.1 or 4.8 mm	Lateral approach (DI) with hinge technique	Autogenous	<4 mm	-	FPD: 40 I SSC: 71 I	Upto 5 years	2 (bio) 11 I dropouts	98% (SLA - 100%) (TPS - 89%)
Kfir et al., 2009[22]	RCT	112	219 D: 3.75–5 mm L: 13–17.1 mm	Indirect using antral membrane balloon elevation	With graft	≤6 mm	≥10 mm	-	0.5–1 year	11 (bio + tech)	95%
Baldi et al., 2011[23]	Prospective study	25	36 D: 3.75–5 mm L: 10–11.5 mm DAE	Crestal approach (IN) with piezosurgery and osteotome	Bio-oss	3–7.5 mm	6.78 mm	Fixed	Upto 5 years Minimum 1 year	1 2 dropouts	97%
Mazor et al., 2011[24]	Clinical report	20	37 L: 13 mm D: 5 mm	Indirect using antral membrane balloon elevation (flapless)	With graft	2–6 mm	-	PFM crowns	1.5 years	0	100%
Fermergård and Åstrand, 2012[25]	Retrospective study	36	53 L: 9–13 mm D: 4.5 mm	Osteotome (IN)	W/O graft	6.3±0.3 mm	4.4±0.2 mm	-	Upto 3 years	3 (tech)	94%
Li et al., 2013[26]	Clinical report	23	33 D: 4.1–4.5 mm L: 10–12 mm	Piezo with hydraulic pressure	Bio-oss	2–5 mm	7.5±0.9 mm	-	2–3 years	0	100%
Gu et al., 2016[27]	Prospective study	25	37: SLA	Indirect approach	W/O graft	≤4 mm (2.81)	-	-	Upto 5 years	2 (bio)	94.6%
Brizeula et al., 2014[28]	Prospective study	37	36 D: 3.5 and 4.1 mm L: 10 and 8 mm	Osteotome (IN)	W/O graft	4–9 mm (7.4±0.4 mm)	1.8±0.3 mm 4 I: >3 mm	Fixed	Upto 2 years	1 (bio) 1 PT drop out	91.6%
Rao and Reddy 2014[29]	Clinical report	34	62	Lateral approach with AMBE	Autogenous	4.2 mm (1.8–6.4 mm)	7.5 mm (5.2–10.5 mm)	-	Upto 3 years	2	96.8%
Cara-Fuentes et al., 2016[30]	Retrospective study	51	76 L: 11.1–11.2 mm D: 4–4.1 mm	Direct with piezo	With and W/O graft	4–7 mm	2.7±0.9 mm 2.6±0.9 mm	-	2–2.5 years 924 days - with 1177 days - W/O graft	With graft: 2 W/O: 1	93% (with) 97% (W/O)
Hussein and Hassan, 2017[31]	Prospective study	24	32 SLA Study group: 16 Control group: 16	Osteotome with AMBE	ORC graft	≤6 mm	6.48 mm	-	1 year	3	90.62%
Molemans et al., 2019[32]	Cohort	26	29 SLA Indirect: 22 Direct: 7 L: 9.61–10 mm D: 4.2–4.8 mm	Indirect with osteotome and direct with piezosurgery	With PRF	6.2±1.5 mm (IN) 4.6±1.8 mm (DI)	3.4±1.2 mm 5.4±1.5 mm	-	0.5 year	2 (bio) (IN)	97.8% (IN) 100% (DI)

DI: Direct, IN: Indirect, FPD: Fixed partial dentures, RCT: Randomized controlled trial, PRF: Platelet rich fibrin, TPS: Ti plasma sprayed, SLA: Sand blasting, large grit and acid etch, W/O: Without, IMM: Immediate, PFM: Porcelain fused to metal, IRRPD: Implant retained removable partial denture, DAE: Dual acid etching, AMBE: Antral membrane balloon elevation, SC: Single crown, SSC: Stainless steel crown, IN: Indirect, DI: Direct, S.T: Surface treatment

Meta-analysis

Follow-up period ≥6 months was considered after implant placement and meta-analysis was obtained for both direct and indirect approach [Tables 4–6 and Figures 2–4]. A forest plot was fabricated [Figures 2–4].

Table 4.

Direct sinus lift technique

Author	Year	n	N	Proportion	95% LL	95% UL
Zitsm Ann et al.	1998	76	79	0.962	0.920	1.004
Tawil et al.	2001	57	61	0.934	0.872	0.997
Bornstein et al.	2008	109	111	0.982	0.957	1.007
Rao et al.	2014	60	62	0.968	0.924	1.012
Carafuentes et al.	2016	72	76	0.947	0.897	0.998
Molemans et al.	2019	28	29	0.966	0.899	1.032
Binary random-effects model
Estimate proportion	95% LL	95% UL		SE		P
0.969	0.952	0.985		0.009		<0.001
Heterogeneity
Τ 2	Q (df=8)			Heterogeneity P		I 2
0	3.076			0.688		0%

LL: Lower limit, UL: Upper limit, SE: Standard error

Table 6.

Indirect sinus lift techniques (overall)

Author	Year	n	N	Proportion	95% LL	95% UL
Zitsmann et al.	1998	76	79	0.962	0.92	1.004
Fuggazotto et al.	2002	163	167	0.976	0.953	0.999
Fugazzotto et al.	2002	114	116	0.983	0.959	1.006
Leblebicioglu et al.	2005	73	75	0.973	0.937	1.01
Kfir et al.	2009	208	219	0.950	0.921	0.979
Baldi et al.	2011	35	37	0.946	0.873	1.019
Maxor et al.	2011	37	37	1.000	0.951	1.023
Fermergard et al.	2012	50	53	0.943	0.881	1.006
Li et al.	2013	33	33	1.000	0.945	1.026
Xin Gu et al.	2014	35	37	0.946	0.873	1.019
Brizuela et al.	2014	33	36	0.917	0.826	1.007
Hussien and Hassan et al.	2017	29	32	0.906	0.805	1.007
Molemans et al.	2019	28	29	0.966	0.899	1.032
Binary random-effects model
Estimate proportion	95% LL	95% UL		SE	P
0.970	0.959	0.981		0.006	<0.001
Heterogeneity
Τ 2	Q (df=8)	Heterogeneity P		I 2
0	9.193	0.686		0%

LL: Lower limit, UL: Upper limit, SE: Standard error

Figure 2.

Forest plot for direct technique

Figure 4.

Forest plot all indirect techniques

Table 5.

Indirect sinus lift technique using osteotome

Author	Year	n	N	Proportion	95% LL	95% UL
Zitsmann et al.	1998	76	79	0.962	0.92	1.004
Fugazzotto et al.	2002	163	167	0.976	0.953	0.999
Fugazzotto et al.	2002	114	116	0.983	0.959	1.006
Leblebicioglu et al.	2005	73	75	0.973	0.937	1.01
Fermergard et al.	2012	50	53	0.943	0.881	1.006
Xin Gu et al.	2014	35	37	0.946	0.873	1.019
Brizuela et al.	2014	33	36	0.917	0.826	1.007
Hussien and Hassan et al.	2017	29	32	0.906	0.805	1.007
Molemans et al.	2019	28	29	0.966	0.899	1.032
Binary random-effects model Metric: Proportion
Estimate proportion	95% LL		95% UL		SE	P
0.971	0.958		0.984		0.007	<0.001
Heterogeneity
Τ 2	Q (df=8)		Heterogeneity P		I 2
0	5.525		0.700		0%
Author	Year	n	N	Proportion	95% LL	95% UL
Indirect sinus lift technique using piezosurgery
Baldi et al.	2011	35	37	0.946	0.873	1.019
Li et al.	2013	33	33	0.985	0.945	1.026
Indirect sinus lift technique using antral membrane balloon elevation
Kfir et al.	2009	208	219	0.950	0.921	0.979
Mazor et al.	2011	37	37	1.000	0.951	1.023

LL: Lower limit, UL: Upper limit, SE: Standard error

Figure 2, forest plot for studies using direct approach[16,17,21,29,30,32] depicted P = 0.688, 95% confidence interval [CI] 0.969.

Figures 3 and 4, forest plot for studies using indirect approach[16,18,19,20,22,23,24,25,26,27,28,31,32] depicted P = 0.686 and 95% CI 0.970.

Figure 3.

Forest plot for indirect technique using osteotome

Graph result

The survival rate of each technique was calculated and given [Tables 7, 8 and Figures 5, 6].

Table 7.

Survival rate of direct approach procedures (%)

Study and year	Sinus floor elevation technique	Survival rate (%)
Zitzmann and Schiirer, 1998[16]	Direct approach with modified Caldwell–Luc	96.2
Tawil and Mawla, 2001[17]	Direct approach with elevation osteotomy	93.4
Bornstein et al., 2008[21]	Direct approach with hinge technique	98.2
Rao and Reddy, 2014[29]	Direct approach with antral membrane balloon elevation	96.8
Cara-Fuentes et al., 2016[30]	Direct approach with piezosurgery	94.7
Molemans et al., 2019[32]	Direct approach with piezosurgery	96.6
Total mean		95.98

Table 8.

Survival rate of indirect approach procedures (%)

Study and year	Sinus floor elevation technique	Survival rate (%)
Zitzmann and Schiirer, 1998[16]	Indirect approach with osteotome	96.2
Fugazzotto and Paoli, 2002[18]	Indirect approach with osteotome	97.6
Fugazzotto, 2002[19]	Indirect approach with osteotome	98.3
Leblebicioglu et al., 2005[20]	Indirect approach with osteotome	97.3
Kfir et al., 2009[22]	Indirect approach with antral membrane balloon elevation	95
Baldi et al., 2011[23]	Indirect approach with piezosurgery and osteotome	94.6
Mazor et al., 2011[24]	Indirect approach with antral membrane balloon elevation	100
Fermergård and Åstrand, 2012[25]	Indirect approach with osteotome	94.3
Li et al., 2013[23]	Indirect approach with piezosurgery	98.5
Gu et al., 2016[27]	Indirect approach with osteotome	94.6
Brizeula et al., 2014[28]	Indirect approach with osteotome	91.7
Hussein and Hassan, 2017[31]	Indirect approach with antral membrane balloon elevation	90.6
Molemans et al., 2019[32]	Indirect approach with osteotome	96.6
Total mean		95.79

Figure 5.

Survival rate of direct approach procedures (%)

Figure 6.

Survival rate of indirect approach procedures (%)

Overall survival rate for direct approach is 95.98% and for indirect approach is 95.79%.

There was no major mean difference in the survival rate of direct approach and indirect approach.

DISCUSSION

Systematic reviews are considered as best evidence from the scientific literature. Different techniques have been used for maxillary sinus lift procedures for implant placement in the posterior maxilla region based on the availability of RBH. Thus, this systematic review was carried out to evaluate the available data on various maxillary sinus floor elevation. Analyzing survival outcomes of implant placed through various direct and indirect sinus lift techniques was one of the primary objectives of this systematic review. Nine clinical studies, six prospective, and two retrospective studies were identified and included in this systematic review. In this review, in vivo studies were included because they are well accepted for supplying basic scientific knowledge and for their clinical relevance.

Sinus lift techniques are most commonly used and highly predictable surgical procedure to overcome bone height deficiencies in the posterior maxilla (Wallace et al. 2007).[15] RBH for all lateral antrostomy procedure was <5 mm and >5 mm for crestal approach [Table 3]. Complications that occurred during sinus floor elevation are: bleeding from sinus membrane or from lateral bony window (Solar et al. 1999), laceration of the buccal flap, injury to infra-orbital nerve, and accidental membrane perforation (Pikos 2006). Modifications with direct as well as indirect techniques used reduced the complications during the procedures. Bone grafting done using bio-Oss and autogenous bone increased the implant survival rate. Furthermore, pre- and post-surgical antibiotic administration helped in infection-free field for surgery and also reduced discomfort to the patient postsurgery.

It is difficult to compare the large number of studies on maxillary sinus lift techniques due to differences in type of implants used, the patient's follow-up and quantity of residual bone present, techniques used, and evaluation methods.[33]

In the present study, a total of 337 implants were placed using direct approach from six included studies. Modifications such as piezosurgery and antral membrane balloon elevation were used in three studies by direct approach. Two studies were carried out using piezosurgery that provided advantage of atraumatic sinus elevation and clear surgical site. Although studies that used Piezosurgery preparation for lateral window approach showed sinus perforation rate of 3.6%.[34]

One study with subantral membrane elevation via balloon was included along with direct approach, which is considered less technique sensitive, proposed by Soltan and Smiler.[35] Few studies[35,36] have documented antral balloon elevation method. Kfir et al.[22] achieved success in 91.6% for initial 12 patients and 100% success in second series of 12 patients, without complications. In antral balloon elevation method along with direct approach, initial procedural success was 100% and implant survival rate 96.8% after 6 months of follow-up.[29] Major advantages of antral balloon protocol are low incidence of infection and bleeding and low risk of perforation of sinus membrane, even in anatomically complex conditions.[37]

A lateral window approach is considered to be performed with a residual bone <5 mm. One-step and two-step lateral antrostomies are performed where one step was performed with RBH 4–6 mm in which simultaneous implant placement was done along with elevation. Moreover, majorly two-step is performed where bone graft material is placed and waited and implant placement is done after 6–8 months.[16] More bone gain was obtained nearly 10–12.7 mm through lateral window approach compared to osteotome technique (Zitzmann et al., 1998).[16]

Out of 337 implants placed, 18 implants failure resulted using direct approach with overall survival rate of 96.9%.

A total of 13 studies are included of maxillary sinus floor elevation using osteotome technique, in which total of 922 implants are placed. The osteotome technique was most frequently performed a study to elevate antral membrane. The advantage of this technique, as contrasted with lateral approach, are that it is less invasive and that it has shorter healing and waiting period. The increase of 3.5 mm of bone was noticed which is slightly below the values reported by summers.[12]

When 4 to 5 mm of alveolar bone is available below the sinus floor, the use of osteotomes is considered less traumatic than repeated malleating to the patients. The author has utilized a formula of 2 × 2 as the maximum size of the implant to be placed following trephine and osteotome core implosion. If 5 mm residual bone is present, maximum of 8 mm implant length will be contemplated. If a longer implant is desirable osteotome with modified trephine technique is imploded.[38]

Out of 13 studies included with indirect approach, nine studies performed osteotome technique in indirect approach with the overall survival rate of 97.1% of osteotome technique. Two studies were performed with indirect approach using Piezosurgery with survival rate 94.6% and 98.5%. Moreover, two studies were performed with antral membrane balloon elevation method with survival rate of 95% and 100%.

Bio-oss graft material showed good clinical results, reported by Hallman and Nordin[39,40] who used it in connection with a conventional sinus lift and Brägger et al.[41] who used it with osteotome sinus floor elevation.

Even there are very limited studies with hydraulic sinus floor elevation that fulfilled the inclusion criteria of the study conducted. Hydraulic forces avoided the rupture of the sinus membrane using osteotome techniques. One study by Li et al. in 2013[26] showed 100% survival rate of implant using hydraulic pressure technique.

Hence, a total of 35 implants failed out of 922 implants placed using indirect techniques with the overall survival rate of 97%.

In this review, implants used were surface treated with Ti plasma-sprayed (TPS) and SLA (sandblasting, large grit, and acid etch). According to Bornstein et al., in their study, SLA implants showed 100% survival rate and TPS implants showed 89% survival rate.[21]

Biological and mechanical complications might cause failure in implant therapy.[42]

The results of the study showed, furthermore extensive future studies are needed especially a randomized control trial as such studies are lacked in the present research study along with newer modifications involving sinus floor elevation using hydraulic pressure and antral membrane balloon elevation methods.

CONCLUSION

Hence, summarizing and highlighting the findings of this systematic review, the following conclusions are drawn:

• Overall survival rate of implants placed by direct approach is 96.9%

• Overall survival rate of implants placed using indirect approach is 97%.

Due to the limited number of well-performed RCT studies published to date, this systematic review concludes that there is no statistically significant difference in the survival rate of implant placed using direct and indirect approach procedures. Hence, the technique is selected as per the indications given for each direct and indirect technique.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.