The purpose of this systematic review was to perform a comparative analysis of the use or not of graft material in maxillary sinus lift surgery. Relevant studies published in the last 10 years were identified through a search of the PubMed/MEDLINE, ScienceDirect, and Cochrane Library databases and were assessed against the study inclusion and exclusion criteria. The initial search resulted in 1037 articles. After applying the inclusion and exclusion criteria, 16 articles remained. Four hundred and thirty-six patients were followed up over a postoperative period ranging from 6 months to 11 years. In total, 868 implants were installed in 397 maxillary sinuses. The implant survival rate was 96.00% for surgeries performed without graft material and 99.60% for those in which biomaterial was used, within a follow-up period of 48 to 60 months. In conclusion, maxillary sinus lift surgery, with or without graft material, is a safe procedure with a low complication rate and predictable results.
The loss of posterior teeth and subsequent maxillary sinus pneumatization results in atrophy of the alveolar bone and can affect the proper rehabilitation of patients with osseointegrated implants. In this context, maxillary sinus lift surgery (also known as maxillary sinus floor augmentation surgery) has been considered a safe treatment modality with a low complication rate. The use of this procedure in order to insert implants was introduced by Tatum and published as a clinical study by Boyne and James. This procedure is suitable for the rehabilitation of both a posterior tooth and a completely edentulous maxilla in regions with loss of alveolar bone and sinus pneumatization.
Traditionally, the success of the maxillary sinus lift procedure is determined by the amount of vital bone formation after maturation of the graft and the long-term survival rate of the implants placed in that region. Two approaches are commonly used: the lateral window technique and the osteotome intrusion technique. The latter is indicated when at least 5–6 mm of alveolar bone is present, showing a gain of 4–8 mm in bone height, and there is sufficient bone to stabilize the implant. The lateral window technique is indicated when large bone gains are required in severely resorbed jaws; implants can be installed immediately if primary stability is obtained, or after bone healing.
Various grafting materials have been used in maxillary sinus lift surgery, including autologous bone, xenogeneic bone, demineralized or mineralized allogeneic bone, and alloplasts. These grafts may have potential for osteogenesis, osteoconduction, or osteoinduction. According to Chen et al., bone formation in the maxillary sinus does not require the presence of biomaterial. The maintenance of space for blood clot formation accompanied by the resorption and deposition of bone cells derived from the sinus periosteum or cancellous bone of the maxilla would be responsible for bone formation in this region.
The intraoperative complication most commonly associated with maxillary sinus lift surgery is perforation of the sinus membrane. Other complications include postoperative infection, sinusitis, exposure of the graft, graft loss, oedema, seroma formation, bleeding, and exposure of the membrane. The objective of this study was to conduct a systematic review through a comparative analysis of the use or not of graft material in maxillary sinus lift surgery using the lateral window technique.
Materials and methods
This systematic review was conducted in accordance with the guidelines of the PRISMA statement and following the models proposed in the literature. Scientific articles were selected by two authors, and there was no disagreement among them regarding the results found.
Relevant studies published during the last 10 years and written in English were identified through a search of the PubMed/MEDLINE, ScienceDirect, and Cochrane Library databases. Two pairs of key words were used in the search: “dental implants” AND “sinus floor augmentation”, and “bone formation” AND “sinus floor augmentation”. The articles were selected by title and abstract and in accordance with the inclusion and exclusion criteria.
Selection of studies
Clinical studies were chosen based on title and abstract. Prospective and retrospective studies were included. The participants, intervention, comparison, and outcomes (PICO) were determined to formulate a specific question. Participants were patients who underwent maxillary sinus lift surgery through the lateral window technique, concomitant with implant placement. The intervention was the maxillary sinus lift procedure and the comparison was that between sinus lift with the use of graft material and without the use of graft material. The outcomes analysed were the rate of new bone formation in the maxillary sinus and the survival rate of the implants installed in the region.
Inclusion and exclusion criteria
Inclusion criteria included articles written in the English language, clinical trials, maxillary sinus lift surgery by lateral window technique associated with the installation of implants, and a minimum follow-up period of 6 months. Exclusion criteria included animal studies, case reports, case series, and literature and systematic reviews.
Evaluation of the reliability and quality
The studies were analysed systematically to identify possible bias in the results and conclusions, and were classified into different levels of evidence following the hierarchy of evidence provided by the National Health and Medical Research Council (NHMRC, Australia).
The following data were identified and extracted from each article: first author, level of evidence, number of patients and average age, number of implants placed in the sinus lift region, bone height before and 6 months after surgery, type of graft material used, implant geometry, period of osseointegration, follow-up period, survival rate of implants placed, and complications associated with the procedure. Data were processed for quantitative and qualitative analyses.
SigmaPlot 12.3 (Systat Software Inc., San Jose, CA, USA) was used for the analysis of the survival rate of implants between groups (with graft material vs. without graft material) according to the follow-up period (0–6 months, 6–12 months, 12–24 months, and 24–36 months). The Shapiro–Wilk homoscedasticity test was applied, which showed homogeneity of the data analysed ( P > 0.05). Therefore, the two-way analysis of variance (ANOVA) test was used for comparisons among the sources of variation (experimental group, period, and group vs. period).
Searches in the three databases yielded 1037 articles. After evaluation according to the inclusion and exclusion criteria and the elimination of duplicate references, 30 articles were selected ( Fig. 1 ). Fourteen of these articles were excluded because they presented sinus lift techniques other than the lateral window technique, or implants were placed at different times after the maxillary sinus surgery. The remaining 16 articles were included in the qualitative and quantitative analyses. Tables 1 and 2 provide a summary of the 16 selected articles.
|Author||Year||Level of evidence||Type of study||Patients ( n )||Operated maxillary sinuses ( n )||Implants ( n )||Average preoperative bone height (mm)||Average postoperative bone height (mm)||Follow-up (months)||Survival||Complications|
|Kaneko et al.||2012||III-2||Prospective||11||11||21||4.7 ± 1.4||10.9 ± 2.2||24–46||95.20%||4 membrane perforation cases|
|Thor et al.||2007||III-2||Prospective||20||27||44||4.6||Average gain of 6.5||14–45||97.72%||11 membrane perforation cases|
|Bassi et al.||2015||III-1||Prospective||17||20||25||5.94||13.14||51||96%||None|
|Sohn et al.||2008||III-1||Prospective||10||10||21||5||NR||6–12||100%||1 membrane perforation case|
|Moon et al.||2011||III-2||Prospective||14||17||31||5||13.25||24||93.50%||2 membrane perforation cases|
|Altintas et al.||2013||II||Prospective||7||10||12||NR||NR||6||100%||None|
|Chen et al.||2007||III-2||Retrospective||33||NR||47||7.5 ± 2.1||Average gain of 4.5||24||100%||None|
|Author||Year||Level of evidence||Type of study||Patients ( n )||Operated maxillary sinuses ( n )||Implants ( n )||Average preoperative bone height (mm)||Average postoperative bone height (mm)||Biomaterial||Follow-up (months)||Survival||Complications|
|Silvestri et al.||2013||II||Prospective||37||42||82||2–5||NR||Deproteinized bovine matrix; particulate swine cortical bone||6||96.34%||None|
|Merli et al.||2013||II||Prospective||40||40||59||2.3; 2.0||11.1; 11.0||Deproteinized bovine matrix; autogenous bone||15||100%; 93.75%||2 cases of perforation of the membrane; 1 case of peri-implantitis|
|Johansson et al.||2010||III-1||Prospective||61||NR||81||3–10||NR||Autogenous bone||12–60||98.80%||3 cases of membrane perforation|
|Sohn et al.||2010||III-2||Prospective||7||9||18||5||NR||Absorbable gelatin sponge||6||88%||1 case of membrane perforation|
|Altintas et al.||2013||II||Prospective||7||10||12||NR||NR||Allogeneic mineralized bone||6||100%||None|
|Trautvetter et al.||2011||III-2||Retrospective||10||15||21||6.9||14.2||Polymer based on autogenous bone graft||60||100%||3 cases of membrane perforation and 1 case of sinusitis|
|Irinakis||2011||III-2||Retrospective||49||49||49||5.09; 4.66||NR||Allograft||12–14||100%||2 cases of membrane perforation|
|Ardekian et al.||2006||III-2||Retrospective||70||110||221||NR||NR||Deproteinized bovine matrix with autogenous bone||12–48||94%||35 cases of perforation of membrane, 1 case of sinusitis, and 1 case of fistula|
|Garlini et al.||2010||III-2||Retrospective||26||27||47||7.4||15||Hydroxyapatite with collagen and glucosamine||48–132||100%||NR|
|Sakka and Krenkel||2011||III-2||Retrospective||17||NR||77||1 to 11||NR||Autogenous bone||12||94.80%||NR|
The selected studies were all classified as retrospective or prospective. The level of scientific evidence in these studies ranged from II to III-2 ( Tables 1 and 2 ). In total, 868 implants were placed in 436 patients, and these patients were assessed over follow-up periods ranging from 6 months to 11 years. Implants were placed in premolar and molar regions of the maxillary sinus submitted to lift surgery, and long implants were predominantly used.
The diameter of the implants used varied from 3.3 mm to 6 mm. Only implants with appropriate primary stability were considered in this study. The minimum period for osseointegration was 3 months and the loss of implants was attributed to the absence of adequate primary stability, especially in the alveoli after tooth extraction.
Three hundred and two maxillary sinus lift surgeries were performed with the interposition of some type of graft material; the materials used ranged from autologous and allogeneic bone to absorbable gelatin sponge. Ninety-five maxillary sinus lift surgeries were performed without the interposition of any graft material, besides the clot. The residual bone height in the region where the implants would be installed ranged from 2 mm to 11 mm, and the implant survival rate ranged from 88% to 100%. Regarding complications related to the procedure, sinus membrane perforation was the most reported. No disturbances in the normal process of osseointegration of the implants were registered.
Four hundred and thirty-six patients aged between 18 and 85 years underwent maxillary sinus lift surgery with the concomitant placement of dental implants. Of the 868 implants, 667 were installed in the maxillary sinuses with biomaterial and 201 with only the clot. There was no statistically significant difference between the groups in the implant survival rate. At 0–6 months of follow-up, the average survival rate of the implants placed in the maxillary sinus without graft material was 97.49% and with graft material was 96.88%. At 48–60 months of follow-up, however, the survival rate was 96.00% for implants in sinuses with no graft material and 99.60% for implants with graft material ( Table 3 ).
|Follow-up (months)||Maxillary sinus with graft material ( n )||Maxillary sinus without graft material ( n )||Survival rate with graft material||Survival rate without graft material|
The implant brands used are shown in Tables 4 and 5 . Implants of 9 mm to 15 mm in length and 3.3 mm to 5 mm in diameter were used in the surgeries without graft material. For surgeries with biomaterials, the implants used were 8 mm to 18 mm in length and 3.3 mm to 6 mm in diameter.
|Author||Year||Patient age, range (years)||Brand of implants||Implant length (mm)||Implant diameter (mm)||Implants ( n )||Period of osseointegration (months)||Survival rate|
|Kaneko et al.||2012||37–70
(Mean 57.00 ± 0.9)
|Thor et al.||2007||19–78
|Astra Tech||9, 11, 13, and 15||3.5, 4.5, and 5||44||3–8||97.72%|
|Bassi et al.||2015||NR||Neodent||13||4.3||25||9||96%|
|Sohn et al.||2008||Mean 50||MIS Implants Technologies and EBI Inc.||10–15||3.7–5||21||6||100%|
|Moon et al.||2011||37–70
|Sybron Implant Solutions||13||4.1||31||6||93.50%|
|Altintas et al.||2013||23–80
|Chen et al.||2007||Mean 55||Straumann, Centerpulse Dental, Friadent GmbH||12, 13, and 15||NR||47||6||100%|