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Year : 2020  |  Volume : 31  |  Issue : 3  |  Page : 389-395
Comparative evaluation of direct sinus lift with bone graft and zygoma implant for atrophic maxilla

Department of Oral & Maxillofacial Surgery, Balaji Dental and Craniofacial Hospital, 30, KB Dasan Road, Teynampet, Chennai, Tamil Nadu, India

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Date of Submission26-Apr-2020
Date of Acceptance25-May-2020
Date of Web Publication06-Aug-2020


Introduction: Implant rehabilitation of atrophic maxilla is challenging. The aim of this manuscript is to compare the clinical outcome of rehabilitation of atrophic maxilla (long span) by zygomatic implants (ZI) versus conventional sinus lift with augmentation procedures dental implants (SLAP-DI). Materials and Methods: A retrospective record analysis of a cohort of 25 patients fulfilling the inclusion and exclusion criteria, over a period of 6 years were performed. The patients had been either treated with ZI or SLAP-DI. The outcome measures were: prosthesis, implant and augmentation failures, any complications, patients' number of days with total or partial impaired activity, time to function and number of dental visits, assessed by independent assessors from records. The data was analyzed using SPSS with P ≤ 0.05. Results: There were 16 (64%) men and 11 (44%) had ZI while 14 (56%) underwent SLAP-DI. There were no prosthesis or implant failures in this cohort. Between ZI and SLAP-DI, there was no gender difference (P = 0.648), border line significance in minor complication (P = 0.075), with less complication encountered in SLAP-DI than the ZI. None of the cases had major complications that required hospitalization or severe medical therapy. Of the 14 cases that underwent SLAP, 11 (78.6%) had no augmentation failure (resorption <10%). ZI had older age (P = 0.000), with greater number of teeth missing (P = 0.002), with lesser time for functional loading (P = 0.000), required less number of visit to dentist (P = 0.000), and lesser bone loss at insertion site (P = 0.005).Discussion & Conclusion: The results are discussed in light of previous pertinent literature. This short term (~ 1 year follow-up) suggest that SLAP-DI and ZI have certain similar features. There is no statistical difference in outcome barring the time needed to functional loading (1.3 days vs. 444.3 days). Relatively more complications were reported for ZI, but had no statistical significance. Long-term and multi-center data are needed to confirm the results.

Keywords: Atrophic maxilla, dental implants, ridge augmentation, sinus lift, zygoma implants

How to cite this article:
Balaji S M, Balaji P. Comparative evaluation of direct sinus lift with bone graft and zygoma implant for atrophic maxilla. Indian J Dent Res 2020;31:389-95

How to cite this URL:
Balaji S M, Balaji P. Comparative evaluation of direct sinus lift with bone graft and zygoma implant for atrophic maxilla. Indian J Dent Res [serial online] 2020 [cited 2022 Jan 20];31:389-95. Available from:

   Introduction Top

Dental implants are increasingly used to replace missing teeth, both anatomically and functionally. The conventional dental implant placement is limited by the requirement of residual bone volume. In atrophied maxillary jaw, the challenge is much pronounced.[1],[2] Besides the systemic factors, local factors and bony contours may provide additional challenges. To address the residual bone deficiency in maxilla, several options like bone augmentation procedures, sinus lift, and non-jaw anchorage principles have been developed over the years.[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13]

For the augmentation, bone graft such as autogenous (iliac crest and rib grafts) or allografts, with or without bone morphogenic proteins (rhBMP2) are used. For some of these procedures, there may be a need for general anesthesia, hospitalization, donor site morbidity, graft resorption (autograft), graft infection/rejections (allografts), and prolonged duration of treatment due to multiple surgeries besides escalating costs due to such procedures. In case of atrophic maxillary jaws, lifting the sinus may also provide some additional bone support. This may be done with or without ridge augmentation to provide additional residual bone support. Since late 20th century, a long screw-shaped implant called zygomatic implant was developed to eliminate the maxillary bone augmentation procedures. Such implants are placed via the alveolar crest to engage the body of the zygomatic bone. The loading may depend on several condition. This has a potential advantage of functional rehabilitation in a single day instead of undergoing staged surgeries.[3],[4],[5],[6],[7],[8],[9],[10],[11],[12],[13],[14]

In spite of the zygoma implants (ZI) being available for more than 2 decades, reliable comparison of the effectiveness and potential risks of ZI with conventional sinus lift with augmentation procedures (SLAP) are still lacking. There is only one reliable cohort of randomized controlled trial published on zygomatic implants with augmentation procedure.[3],[8] Hence this retrospective study was designed to compare the clinical outcome of immediately loaded cross-arch maxillary prostheses supported by zygomatic implants versus conventional implants placed in augmented bone for the rehabilitation of patients with atrophic or severely atrophic maxillary jaw at a 1 year period.

   Materials and Methods Top

The case records of patients who reported for dental implants with atrophic maxilla (for more than 6 teeth in the arch) to authors center and treated with dental implants (with sinus lift and or ridge augmentation) or zygoma implants were enrolled for the study. The case that underwent procedures after January 2012 to December 2017 were considered. All basic demographic details such as age, gender, number of missing teeth, follow-up period were collated from the case records.

Inclusion and exclusion criteria

Patients of either gender with a severely atrophic maxilla without sufficient bone volume for placing dental implants in anterior area (minimal diameter 3.5 mm and length of 8 mm) or less than 4 mm residual bone height under the maxillary sinus, greater than 18 years of age, consenting for the procedure. Patients who had follow-up for at least 2 years were only considered and if required, they were contacted for clinical examination. Presence of radiological images in the records was a must to be included in this retrospective study.

Only patients with healthy sinuses were asked to join the trial. Patients were not included if they had any general contraindications to implant surgery, any medical irradiation, immunosuppressed, patients on bisphosphonates, severe co-existing periodontal disease, autoimmune diseases, uncontrolled diabetes, pregnant or lactating; addiction to alcohol, long-term medications that influence salivary flow such as psychiatric problems, patients using areca nut or smoking more than 10 cigarettes per day, lack of opposite occluding dentition/prosthesis, with restricted mouth opening (less than 3 finger breadth), previous failed treatment and recent trauma. Cases that had no proper documentation, follow-up, or those who did not turn up for regular check-up were not included. Pre-, immediate and post-treatment radiographs (at end of 1 year) were reviewed by authors.

Implant placement

After assessing the radiographic images, CBCT/CT scans were also performed to better plan the implant insertion angles. Anatomical landmarks to be avoided, such as the infraorbital foramens and the correct implant insertion axes, were formulated. The most appropriate position and angle of each implant were pre-determined in each cases. Efforts were made to plan implant exits at crestal level rather than palatally.

Sinus lift augmentation procedure and dental implant placement

In this procedure, direct sinus lift procedure was carried out. It was done under general anesthesia, if iliac cancellous bone graft is obtained.

Ridge Augmentation procedure: Any ridge augmentation procedure was carried out using standard procedures, as described previously.[11]

Sinus Augmentation and Implant - Standard sinus lift procedures were carried out by direct sinus lift procedure as previously described.[13] Autogenous bone grafts was either obtained from iliac crest using standard technique and a bone mill was used to grind the bone shaving into fine particles. After adequate local anesthesia and site preparation, a surgical incision was placed on the crest of atrophic ridge such that there is a vertical releasing curvilinear incision flaring into the vestibule. Full-thickness, subperiosteal labial, and palatal flaps were raised, reflected. The design was such that base of flap broad as well as adequate buccal and palatal tissue for good closure. The bony anterolateral wall of maxillary sinus was visualized. Previously determined dimension of osteotomy was checked and carried out. A buccal bone window was made on exposed wall of maxillary sinus using a postage stamp method. The bony wall was gently manipulated with sinus membrane elevators without damaging Schneiderian membrane. Between the floor and the raised membrane, the crushed bone was placed and packed. The implant was placed on same sitting with help of a stent which was positioned, then removed, and the site was checked for appropriate faciolingual and mesiodistal positioning. Any abnormal crestal defects, if noted were corrected. A pilot drill of 2 mm in diameter was then drilled in marked implant site on RAB to establish depth and axis of implant recipient site. The implant was placed with its axis parallel to occlusal forces. Paralleling pins were employed as necessary to check parallelism of drill holes. The drills were used in a standard reduction gear hand piece along with a physiodispenser enabling copious saline irrigation to prevent excessive heat generation. The drill was used at the speed of 800–1,000 rpm. Drills with gradually increasing diameters were used to enlarge implant recipient site till the desired diameter corresponding to implant's diameter was reached. Implants were then placed into the prepared site using a torque wrench. 3-0 Vicryl sutures were used to close the surgical wound [Figure 1], [Figure 2], [Figure 3].[13]
Figure 1: (a and b) - case of papillon-lefevre syndrome (c) OPG shows severe bone loss with grade 3 mobility of all teeth.(d) CT coronal shows paper thin bone in the maxillary sinus and alveolus (e) Clinical picture showing mobile teeth (f) Iliac cancellous bone graft harvested (g and h) right and left direct sinus lift procedure (i) Postoperative Orthopantomogram X-ray (j) Esthetically designed suprastructure

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Figure 2: Case of severe periodontal disease- mobility and loss of teeth (a) OPG shows missing teeth following severe periodontal disease (b) CT shows thin alveolar bone in the maxillary region (c) Rib graft harvested from the patient (d, e, f and g) Right and left direct sinus lift and packing sinus with rib graft (h) Osseointegrated implants (i) Esthetically designed suprastructure

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Figure 3: Partial edentulousness due to caries and extraction (a) OPG shows missing teeth and retained deciduous (b) CT shows alveolar bone with vertical thickness ranging from 4 to 6 mm (c and d) Direct sinus lift with allogenic bone material and immediate implant placement (e) OPG shows osseointegrated implants (f) Esthetically designed suprastructure

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Subsequent to the procedure, the following medications were prescribed for the patient; Augmentin 1.2 gm injection IV twice a day, Metrogyl 500 mg injection IV twice a day, Dalacin C injection IV 300 mg twice a day, Pan 40 mg injection IV twice a day, Diclomol tablet twice a day after meals for 5 days. The patient was recalled on day 3, day 10 and at 1 month for postoperative check-up. It was also advised to avoid blowing the nose and to use drinking straws and to keep the mouth open in case of sneezing in order to decrease intrasinus pressure.

Zygoma implant placement[1],[2],[3],[8]

One zygoma implant per quadrant was used. After standard preparation under general anesthesia, at the residual alveolar ridge, as per previous planning, crestal and release incision were placed and a mucoperiosteal fiap was elevated to expose the bone. Landmark such as infraorbital foramen and the incisura between the zygomatic arch and the lateral and medial surface of the frontal process of the zygomatic bone were identified. If required, the window was extended. It is to ensure that the ZI do not cross the sinus or involve its wall. In complex situation, templates were used as guides. The lateral and medial surface of the anterior process of the zygomatic bone were identified to have an orientation of locoregional anatomy to the planned. Insertion began with a round bur with adequate cooling with saline irrigation. Sequential enlargement with a 2.9 mm diameter twist drill was used to penetrate the outer cortical layer of the zygomatic bone along the incisura. The length of the zygomatic implant was reconfirmed using a straight depth indicator. Then a 3.5 mm diameter pilot drill followed by the 3.5 mm twist drill. A ZI system (Nobel Biocare, Gothenburg, Sweden) of the appropriate lengths and a diameter of 4 mm were inserted. Insertion torque of 40 Ncm was achieved to ensure immediate loading. During this process, engagement of both cortex was achieved. Flaps were then sutured with simple, interrupted 4-0 resorbable sutures (Vicryl, Ethicon FS-2, Johnson & Johnson, New Brunswick, NJ, USA) around the impression copings [Figure 4] and [Figure 5].
Figure 4: Severe periodontal disease, mobility and infection followed by extraction (a) OPG shows infected teeth with mobile bridge (b) CT Scan shows very thin alveolus (c and d) Clinical picture showing very poor periodontal status and tooth extraction e and (f) Intraoral picture showing implants with healing abutments (g) OPG shows osseointegrated zygoma and other implants (h) Esthetically designed suprastructure

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Figure 5: Mobile implant supported bridge with infection (a) OPG shows infected implants with bridge b and (c) After partial removal of mobile bridge and implants (d) After complete removal of mobile implants (e) CT scan shows thin alveolus (f) Clinical picture shows right and left zygoma implants with direct sinus lift (g) OPG shows zygoma implants with other implants (h&i) Esthetically designed suprastructure

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Prosthetic procedures

Prosthetic procedures at implants to be immediately loaded were initiated immediately after flap suturing. Radiographic confirmation done. The impression copings in position were stabilized. A rubber base impression was taken, using a previously prepared customized acrylic tray. Healing caps were positioned before a screw-retained metal reinforced acrylic cross-arch provisional prosthesis was delivered within 1 week. About 12 weeks after initial loading, a radiographic examination was done. If found suitable, the provisional prostheses were removed, implant stability was checked by tightening the abutment screws with a 15 Ncm torque using a manual torque wrench. Later, an impression at abutment level was taken and an implant bridge with ceramic or acrylic veneer materials were to be delivered. Patients were recalled for once every 2 months for the first 1 year. Dental occlusion was cross-checked each such maintenance visit. Follow-ups were conducted by trained junior dentists.

Outcome measures[3],[8]

The following outcome measures were considered:

  1. Prosthesis failure: Was defined as a supraprosthesis that could not be delivered because of implant failures or prosthesis replacement because of any reasons.
  2. Implant failure was defined as a ZI or SLAP implant that required removal had become unusable. Rotating (>180°) implants deemed as failures and were removed. Any biological or prosthetic complications.
  3. Failure of the augmentation procedure, if there is greater than 10% of residual alveolar bone height at the crest. Only for SLAP.
  4. Peri-implant marginal bone levels on periapical radiograph that were reported at the end of the 1 year post-loading follow-up, as compared to immediate radiograph (greatest bone loss, in mm). For SLAP, it is at the point of entry.
  5. The number of days patients had total or partial impaired activity: Days of overall impaired activity are those days that, in the patient's opinion, he/she could only partially or totally perform his/her ordinary life activities, including work. This should have been assessed at the delivery of the definitive prostheses. For SLAP, it includes both the augmentation and implant placement
  6. Time to function: Number of days from the first surgical intervention to delivery of the implant-supported provisional prosthesis.
  7. Number of sessions with the clinician: The total number of appointments, including those for maintenance and treatment of complications, required by the patient over the entire follow-up period (up to 1 year post-loading).

All statistical analyses were conducted using the Statistical Package for Social Sciences Software (IBM Corp. Released 2012. IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp). Basic descriptive statistics were presented for the variables. Chi-square tests and comparison of means were used to identify the difference between the two study groups. P ≤ 0.05 was assumed to be statistical significance.

   Results Top

In all, there were 47 cases that had sought implants in atrophic maxilla. Of these, 25 cases fulfilled the inclusion and exclusion criteria. Of them, 16 (64%) were males and 11 (44%) had ZI while 14 (56%) underwent SLAP-DI. The basic demographics are given in [Table 1]. There were no prosthesis or implant failures reported at the end of 1 year period.
Table 1: Basic demographics of the study population

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[Table 2] shows the comparison between ZI and SLAP-DI. There was no difference in gender (P = 0.648), border line significance in minor complication (P = 0.075), with less complication encountered in SLAP-DI than the ZI. In all there were 13 (52%) of minor complications ranging from delayed healing, maxillary sinusitis to peri-implantitis. None of them had major complications that required hospitalization or severe medical therapy. Of the 14 cases that underwent SLAP, 11 (78.6%) had no augmentation failure (resorption <10%).
Table 2: Comparison among study groups

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[Table 3] shows the difference between ZI and SLAP-DI in terms of age in years, number of missing teeth, number of implants, total infirmity period, in days, overall infirmity period, in days, time to functional loading in days, number of visit to dentist and the bone loss at insertion site in mm. Of this ZI had older age (P = 0.000), with greater number of teeth missing (P = 0.002), with lesser time for functional loading (P = 0.000), required less number of visit to dentist (P = 0.000), and lesser bone loss at insertion site (P = 0.005)
Table 3: Difference between the study groups based on outcome measures considered

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   Discussion Top

This retrospective study was designed to comprehend the best method to restore an atrophic maxilla among SLAP-DI or with ZI. From the results, it appears that each of the system has its own advantages. With respect to bone resorption, even with rhBMP2 enhancement, there is a varying degree of loss of the augmentation, with sinus lift procedure. This loss of augmented bone ranged from 2 to 24% with a mean of 8.86 ± 6.34% loss. This, in severe cases, appears to lead to a progressive disastrous condition of a gap appearing between the prosthesis and the residual jaw bone. This gap would and had predisposed to accumulation of food debris, in at least 3 cases. However, such complications are manageable, by repeating the prosthesis. The absence of failures (both implant and prosthesis) as compared to existing literature could be attributed to better surgical approach, meticulous planning, preoperative imaging and better prosthesis planning as well as frequent check-up. With regards to complications, there appears to be no statistical significance between ZI and SLAP-DI. As these results are of only short time (about 12 months), it would be prudent to wait for longer follow-ups (up to 10 years) before drawing definitive conclusions. Transient minor complications such as infection at intra-oral sites and maxillary sinusitis are relatively rare in this cohort, but more common in ZI. But there is no statistical difference in occurrence. These mirror previous finding in literature.[15],[16]

There was no difference between the groups and the total infirmity days were similar for both groups. The number of visits required for having the ZI or SLAP-DI were significant. SLAP-DI required more visits that ZI. The difference was statistically significant, mirroring previous similar findings.[15],[16]

ZI had shorter time to functional loading with statistical significance, which would be definitely attractive to patients. Similarly the loss of crestal bone at the point of entry was less in ZI than SLAP-DI. As the philosophies of the system are entirely different, the significance of this finding cannot be gauged.

The present study indicated that though the ZI had better clinical parameters, it did have sufficient risk as complications did occur, suggesting that their use should be limited to patients with severely atrophic maxilla, especially when the options are limited. It is our observation that in spite of having SLAP, proper implant planning is the crucial phase along with the proper maintenance.

The main limitations of the present retrospective investigation that this has small number of included patients, with no stratification, no randomization and all drawback of a retrospective study design. However, this study reflects some salient features. Both ZI and SLAP-DI were tested in real clinical conditions. The results, in general, are translatable to large sample population. However, this is single center perspective and placement of ZI and sinus lift are complex procedures requiring skilled and experienced operators. If not adequately planned, potentially severe complications may occur.

   Conclusions Top

Short-term comparison of ZI with SLAP-DI has been presented from this part of the world. Dental implant placement is influenced by several factors including financial considerations, patient's choice, locoregional anatomy, residual bone volume and systemic health status. Both system appears to function well. From this study, it could be safely inferred that SLAP-DI could be preferred and if the maxilla is severely atrophic, ZI could be considered. Zygomatic implants are a better rehabilitation modality for severely atrophic maxilla while conventional ridge augmentation with concomitant sinus lift procedure gives better result when there is small span of edentulousness and minimal ridge. Long-term data and multicentric studies are needed to confirm these results.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Brånemark PI, Hansson BO, Adell R, Breine U, Lindström J, Hallén O, et al. Osseointegrated implants in the treatment of the edentulous jaw. Experience from a 10-year period. Scand J Plast Reconstr Surg Suppl 1977;16:1-132.  Back to cited text no. 1
Davó R, Felice P, Pistilli R, Barausse C, Marti-Pages C, Ferrer-Fuertes A, et al. Immediately loaded zygomatic implants vs conventional dental implants in augmented atrophic maxillae: 1-year post-loading results from a multicentre randomised controlled trial. Eur J Oral Implantol 2018;11:145-61.  Back to cited text no. 2
Esposito M, Grusovin MG, Felice P, Karatzopoulos G, Worthington HV, Coulthard P. Interventions for replacing missing teeth: Horizontal and vertical bone augmentation techniques for dental implant treatment. Cochrane Database Syst Rev 2009:CD003607. doi: 10.1002 / 14651858.CD003607.pub4.  Back to cited text no. 3
Pistilli R, Felice P, Piatelli M, Nisii A, Barausse C, Esposito M. Blocks of autogenous bone versus xenografts for the reha- bilitation of atrophic jaws with dental implants: Preliminary data from a pilot randomised controlled trial. Eur J Oral Implantol 2014;7:153-71.  Back to cited text no. 4
Stevenson AR, Austin BW. Zygomatic fixtures – The Sydney experience. Ann R Australas Coll Dent Surg 2000;15:337-9.  Back to cited text no. 5
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Aparicio C. A proposed classification for zygomatic implant patient based on the zygoma anatomy guided approach (ZAGA): A cross-sectional survey. Eur J Oral Implantol 2011;4:269-75.  Back to cited text no. 7
Esposito M, Barausse C, Pistilli R, Sammartino G, Grandi G, Felice P. Short implants versus bone augmentation for placing longer implants in atrophic maxillae: One-year post- loading results of a pilot randomised controlled trial. Eur J Oral Implantol 2015;8:257-68.  Back to cited text no. 8
Triplett RG, Schow SR, Laskin DM. Oral and maxillofacial surgery advances in implant dentistry. Int J Oral Maxillofac Implants 2000;15:47-55.  Back to cited text no. 9
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Balaji SM. Augmentation of residual alveolar bone height with tissue engineering for dental implant placement. Indian J Dent Res 2014;25:410-2.  Back to cited text no. 11
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Balaji S M. Direct v/s Indirect sinus lift in maxillary dental implants. Ann Maxillofac Surg 2013;3:148-53.  Back to cited text no. 13
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Balaji P, Balaji SM, Ugandhar P. Dental implants for severely atrophied jaws due to ectodermal dysplasia. Indian J Dent Res 2015;26:205-9.  Back to cited text no. 14
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Hirsch JM, Öhrnell LO, Henry PJ, Andreasson L, Bråne- mark PI, Chiapasco M, et al. A clinical evaluation of the Zygoma fixture: One year of follow-up at 16 clinics. J Oral Maxillofac Surg 2004;62:22-9.  Back to cited text no. 15
Esposito E, Davó R, Marti-Pages C, Ferrer-Fuertes A, Barausse C, Pistilli R, et al. Immediately loaded zygomatic implants vs conventional dental implants in augmented atrophic maxillae: 4 months post-loading results from a multicentre randomised controlled trial. Eur J Oral Implantol 2018;11:11-28.  Back to cited text no. 16

Correspondence Address:
Dr. S M Balaji
Director & Consultant Oral & Maxillofacial Surgeon, Balaji Dental and Craniofacial Hospital, 30, KB Dasan Road, Teynampet, Chennai - 600 018, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijdr.IJDR_410_20

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

  [Table 1], [Table 2], [Table 3]

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