Predictable Sinus Augmentation: Viable Options for the General Practitioner

INTRODUCTION

Reconstruction of edentulous areas with dental implants is a viable alternative to conventional dental procedures and has become rather mainstream within the profession and to our patients. Candidates must exhibit adequate quality and quantity of bone prior to any surgical intervention to meet the patient’s requirement for emergence profile and tooth design. Anatomical considerations are evaluated, and treatment options are presented to the patient. When procedures are done well, patients receive therapy that is relatively routine and non-stressful, providing both function and aesthetics.

The lack of available hard tissue complicates the ability to physiologically integrate bone to the surface of dental implants. Dental implants have proven to be a practical alternative to many conventional dental therapies. Loss of teeth may result in horizontal and vertical changes of potential restorative sites. This diminished framework prohibits many from attempting to incorporate dental implant therapy into their workflows especially in the posterior mandible and maxilla. The apprehension is the result of the positioning of the mandibular nerve and large maxillary sinuses.  

CBCT analysis has allowed for a predictable view of vital anatomy and provides an opportunity to virtually diagnose, plan, place appropriate fixtures, and even determine restorative emergence profiles. Situations arise where sites need to be augmented to increase the volume of bone. Advanced grafting techniques provide the practitioner with the opportunity to augment deficient sites predictably. Regeneration may appear to consist of a complex series of steps. The posterior maxilla provides some unique concerns following tooth loss. Not only does the bone in the area resorb vertically and horizontally, but without root support, the floor of the sinus may collapse, increasing the volume or space that is not suitable for dental implant placement.

Grafting materials of various types are available to increase volume and eventually provide a foundation for stability and integration of implants and prosthetic construction.¹ These graft materials are used to promote the scaffold for new bone generation as they resorb over time. Osteogenesis, osteoinduction, and osteoconduction are the mechanisms of action to replace viable bone. Consequences of bone loss include decreased width and height of supporting bone and often diminished function and aesthetic features of the face. Quality of life may be reduced with the lack of teeth or the use of removable appliances. Proper chewing function is minimized, affecting proper digestion and nutrition. Grafting at the time of extraction certainly helps minimize bone loss and supports soft-tissue architecture. Periodontal pathology may be prevented, and adequate sites for dental implant placement can be provided in a short 3-to-6-month period. Extractions without grafting may result in soft-tissue infiltration into the sockets and possible loss of valuable ridge height and width. It is reported that there is potentially a 30% to 60% loss of bone in a 3-year period, which may result in the need for more invasive grafting procedures in the future.² All skeletal bone demonstrates volume stability over time except dental alveolar bone because the dental alveolus is very labile in the absence of loading.^2,3 Bone grafting is possible because bone tissue, unlike other tissues, can regenerate completely, provided there is space for the bone to grow. As native bone grows, it will generally replace the graft material completely, resulting in a fully integrated region of new bone. The biological mechanisms that provide a rationale for bone grafting are the aforementioned osteogenesis, osteoinduction, and osteoconduction. Osteogenesis is the ability to create bone cell development and is possible when using host autogenous particulates or blocks. Osteoinduction is the ability to stimulate those cells capable of formulating bone cells, such as bone morphogenic proteins and platelet-derived grown factors. This is a chemical process. Osteoconduction, which is discussed in this article, is a structure that is created to support or scaffold bone development and is a physical process.⁴ Osteoinduction may occur with some allograft materials as bone morphogenic proteins induce stem cells to differentiate into osteoblasts. The graft harvested from a human is acid-washed and buffered to remove minerals and expose growth factors and proteins to influence new bone growth. Osteoclasts release hydrochloric acid to break down bone, releasing stem cells for new bone formation. Demineralized allograft is considered osteoinductive, and the mineral layer has been removed to speed up the process.⁵ 

The world of grafting materials is immense. In today’s marketplace, mineralized and demineralized allografts are available. The mineralized allograft blend discussed in this article is a blend of cortical and cancellous particulates. It provides an osteoconductive matrix for rapid site revascularization and structural integrity. Bovine, equine, and porcine xenografts are also present but will not be discussed here. Alloplastic materials have seen many transitions from hydroxyapatite to beta-tricalcium phosphates, calcium sulfates, polymers, bioactive glass, and calcium phosphates of various compositions and sintering. Allografts need to be protected from invagination of epithelium to allow for the integration process to proceed physiologically without interference. Many membranes are also available to the practitioner but must be chosen carefully to promote the desired result. The resorbable membrane discussed here resorbs in 3 to 4 months and comprises purified intact collagen from porcine peritoneum tissue. It is easily repositioned for precise adjustments and placement (Newport Biologics [Glidewell]).

The alloplastic material used is referred to as an OsteoGen Plug (IMPLADENT LTD). It is a homogenous mixture of OsteoGen graft crystals and bovine Achilles tendon collagen. The combination of bioactive crystal particulate bone graft with purified collagen makes socket preservation easy and affordable, and it is effectively used without the need for a membrane. The design restricts migration of connective tissue through both a physical and chemical barrier. The physical barrier is created as the material is compressed into the defect. This compression gives the epithelial cells a choice: to fight through the condensed material or simply go over the top. Cells will choose the path of least resistance.⁶

When new bone contacts the residual graft particulate, osteoconduction results. A negative effect of using allograft particles is that they may be difficult to compress into a large space and tend to migrate. Osteogen crystals may be used alone or in combination to develop bone growth. They are processed using a low-temperature process. The unique calcium to phosphate ratio created is like human bone.⁷ The material is non-antigenic and bioactive while preventing migration of connective tissue. It also provides the osteoconductive scaffolding needed to maintain a space over time. A prime cellular environment is created during the conversion of the material. The OsteoGen alloplastic material is specifically created, is non-sintered, and is not a ceramic. Calcium ions are afforded into the surgical site where bone conversion occurs at an optimal level.^8,9 

CBCT analysis (Vatech America) determines the available hard tissue and vital anatomy, showing the axial, sagittal, and coronal planes. The axial plane is the plane parallel to the ground, thus dividing the face from top to bottom. The coronal plane shows the plane perpendicular to the ground, dividing the face from front to back. Finally, the sagittal plane is the one perpendicular to the ground, dividing the face from right to left. The sagittal view, in specific facial areas, is useful to determine the width and height of available bone prior to any surgical intervention.^10,11

CASE REPORT

Figure 1 illustrates a sagittal view of the CBCT analysis in a case where there is inadequate volume of bone in the maxillary molar area to accept dental implants. The rationale chosen here for layering allograft and the specific alloplastic material is that the OsteoGen material is easily delivered and allows elevation of the Sneiderian membrane effectively without migration of particulate. It is easy to control and condense. The bioactive nature of the crystals demonstrates enhanced bone mineralization by controlling the migration of connective tissue as it resorbs. Mineralized and demineralized allografts have been shown in several studies to produce up to 60% or more epithelial cells in surgical interventions.¹² The allograft support alone for eventual implant placement, integration, and restoration may be compromised in compression.⁹ The initial proliferation of osteoblasts through OsteoGen Plugs is between 3 and 6 times greater when compared to xenografts or allografts. It appears that the bioactive alloplastic material clinically demonstrates biocompatibility.   

Figure 1. The sagittal view of the CBCT analysis indicates inadequate volume of bone in the maxillary molar area to accept dental implants.

Limitations are often apparent when considering dental implant therapy in the posterior maxillary area. The maxillary sinuses lay under the cheeks, below the eyes, and above the teeth on either side of the nose. The sinuses drain into the nose through ostia on the side of each sinus wall. These holes empty into meatuses in the nasal cavity. The meatuses are covered by turbinates, or bony shelves, surrounded by erectile soft tissue.¹⁰ The maxillary bone in the posterior part of the maxilla is relatively soft (Type IV). The bone is trabecular and porous with thin cortical plates. This allows the skull to be light. Surgical placement of dental implants in this softer bone may be compromised and requires initial stability of the implant by surface integration. In addition, occlusal forces placed on restorations in this posterior part of the arch are extensive. Chewing forces are great, yet the bone is weakest.

Maxillary molars have 3 roots to best withstand occlusal forces. These roots hold up the sinus floor, but when teeth are lost, the sinus may collapse. This is one particular area of consternation for many practitioners. To be able to restore this edentulous space, an invasive surgical procedure referred to as a Caldwell-Luc sinus elevation may be considered. The lateral window sinus augmentation procedure is very useful in gaining height and width of hard tissue. The maxillary sinus Schneiderian membrane can be elevated and stretched about 3 to 6 mm without complication. It consists of a bilaminar design with ciliated columnar epithelial cells on the internal side and periosteum on the osseous side. Tearing of the membrane may result in sinus trauma and could affect the osseointegration of dental implants. The Caldwell-Luc surgical procedure is best used when the quality and quantity of bone in the posterior maxilla is compromised by a large sinus. This occurs when the site has been edentulous over a long period of time, when excessive trauma of the site occurred during an extraction, or when grafting of the socket is not completed at the time of extraction. Sinus tenting is another approach to this problem but is used for nominal increases in bone availability.¹³

The Caldwell-Luc procedure creates a window on the buccal aspect of the missing dentition, and the sinus is filled with grafting materials. After an appropriate integration time, the graft material converts to bone, allowing for surgical placement of dental implants and subsequent restoration with implant-retained crowns. Figure 2 illustrates a clean crestal incision made without vertical incision into the mucosa, exposing the facial bone, which is the site for the lateral window preparation. The Caldwell-Luc surgical procedure creates a bony window to give access to the sinus wall. From this opening, the sinus area is grafted. The intent is to provide adequate height and width of viable living bone to successfully incorporate integrated dental implants, restoring an edentulous situation to function. The ideal location for the lateral window preparation has been investigated to be approximately 3 mm superior to the sinus floor and 3 mm distal to the sloping anterior wall.¹⁰ This allows for controlled augmentation and minimizes the chances of dehiscence of the Schneiderian membrane. Determining the number of implants needed and the position of any anterior teeth is an important factor in the size of the augmentation and design of the lateral window. The amount of graft material absorbed after maxillary sinus augmentation averages 25% for one year, with an average loss of about 2 mm. Limitations to this procedure include any disease processes, lesions, or masses within the sinus itself; very thick or very thin sinus walls; or vital anatomy that may inhibit proper technique, including impingement of the septum.¹¹ The posterior lateral nasal artery, the infraorbital artery, and the posterior superior alveolar artery are present in the surgical environment and need to be respected. A clean, full-thickness mucoperiosteal incision was made at the crest of the edentulous site.^13-15 

Figure 2. A clean crestal incision was made without vertical incision into mucosa, exposing the facial bone, which was the site for the lateral window preparation.

The reflection allowed for complete exposure of the lateral bone site. A piezotome provided accuracy, safety, and comfort in achieving the desired effect much better than a chisel and hammer or a high-speed bur would have. The positive treatment modality of creating the significant window in the lateral aspect of the maxillary posterior region was easily accomplished using the piezotome (Piezotome CUBE [Acteon]). The hard tissue was incised carefully with specifically designed tips. This allowed for a controlled and accurate trough that prepared the created window to be elevated superiorly. Piezoelectric bone surgery is used to reduce heat and pressure at sites where the osseous tissue is removed, contoured, or otherwise manipulated in some dental procedures. The ultrasonic provides a resonating cutting service and can be used for a myriad of procedures, including implant surgery, ridge expansion, and bone graft harvesting. The oscillations and vibrations provide cavitation or cutting only on mineralized tissue.¹⁶ Bone regeneration appeared to be thorough and relatively atraumatic to the surgical site. Control is paramount, and excellent visualization of the osseous incisions must be clear.  

Figure 3. The round bur piezotome was used to make penetration into the hard tissue.

Figure 4. A variety of shaped burs were used to prepare the lateral window through the hard tissue without trauma to the Schneiderian membrane.

Figure 5. The completed preparation.

Figures 3 to 5 illustrate the use of a round bur piezotome to penetrate into the hard tissue. A variety of shaped burs were then used to prepare the lateral window through the hard tissue without trauma to the Schneiderian membrane to complete the window preparation. The facial bone was elevated, similar to that of a reverse dishwasher door. The lateral plate was slowly and carefully elevated, creating a new cortical floor for the augmentation mate (Figure 6).

Figure 6. The facial bone was elevated, similar to that of a reverse dishwasher door. The lateral plate was slowly and carefully elevated, creating a new cortical floor for the augmentation material.

Figures 7 and 8 illustrate how the first layer of OsteoGen Calcium Apatite material had enough firm substance to carefully lift the sinus floor. Enough material was placed to be the primary graft material, providing valuable height of augmentation. Figures 9 to 11 show how the facial defect was then grafted with allograft. The particulates were easily controlled at this stage.

Figures 7 and 8. The first layer of OsteoGen Calcium Apatite material (IMPLADENT LTD) had enough substance to carefully lift the sinus floor. Enough material was placed as the primary graft material, providing the valuable height of augmentation.

Figure 9. The facial defect was grafted with allograft. The particulates were easily controlled at this stage.

Figure 10. An OsteoGen sheet was placed between the sinus and facial grafting to hold the material and allow the epithelium to heal over the surgical site.

Figure 11. A resorbable porcine membrane was the final protection in the surgical site.

An OsteoGen sheet was placed between the sinus and facial grafting to hold the material and allow the epithelium to heal over the surgical site. A resorbable porcine membrane is the final protection of the surgical site. A mattress Newport Biologics Vicryl PGA suture (Glidewell) was used to reposition the reflection and maintain attached gingiva on the facial aspect of the ridge (Figure 12). Figure 13 illustrates the postoperative CBCT analysis of the graft, which was well contained within the sinus framework. The site was allowed to integrate for approximately 4 months, after which a new CBCT analysis indicated bone turnover. The tissue was reflected, and the available bone was evaluated (Figures 14 to 16).

Figure 12. The reflected attached gingiva is repositioned with a Vicryl (PGA) mattress suture (Newport Biologics [Glidewell]).

Figure 13. The sagittal view of the immediate postoperative CBCT indicated a well-contained augmentation of the sinus through the lateral bone.

Figure 14. Four-month post-op CBCT illustrated an adequate integrated site for implant placement.

Figures 15 and 16. Four-month tissue healing and new reflection illustrating the bone turnover.

Two Glidewell HT Implants were strategically placed in the previously inadequate site and torqued to an impressive 45 Ncm, indicating very nice initial stability (Figures 17 and 18). Vicryl sutures were again used to close the reflection following implant placement, and the implants were allowed to integrate for an additional 4 months (Figures 19 and 20). Following the integration of the implants, they were uncovered and impressed with polyvinylsiloxane impression material. After this analog impression was made, 3-mm healing abutments were torqued to 25 Ncm to allow a healthy tissue cuff to form prior to implant-retained crown seating (Figures 21 to 23). The final screw-retained implant crowns were torqued to 35 Ncm, providing function in a previously challenged anatomical site (Figure 24).

Figures 17 and 18. Two dental implants were strategically placed and torqued to an impressive 45 Ncm in the edentulous maxillary posterior.

Figures 19 and 20. The site was sutured, and the implants were allowed to integrate for an additional 4 months.

Figures 21 to 23. After integration, the implants were uncovered and impressed, and the 3-mm healing abutment was placed. This created a healthy gingival cuff prior to implant-retained crown seating.

Figure 24. Final sagittal view of the integrated implant and implant-retained crown.

CONCLUSION

Bone-grafting procedures are the foundation for proper and complete integration of dental implants, especially in compromised situations. The posterior maxilla presents a special challenge in that the titanium fixtures cannot be placed in the air cavity of the maxillary sinus.

Procedures are available to build the hard tissue properly in this area using a variety of grafting materials. With proper training, the sinus area can be exposed with a lateral window bony incisions using a Piezo and the sinus floor elevated to prepare the site for dental implant placement. A layering technique was used here, first with the OsteoGen Plug material, which has some substance to it, lifting the Sneiderian membrane and providing a substrate for the sinus fill. Allograft was then used to complete a new facial wall. This allograft was protected from invagination of epithelium and a layer of a resorbable membrane, followed by the use of an OsteoGen sheet. Integration of the graft was complete, as demonstrated here, providing the foundation for implant placement and functional restoration of the edentulous space.

REFERENCES

1. Beals DW. Bone grafting materials for ridge preservation: Choosing the most appropriate graft material is key to successful outcomes. Decisions in Dentistry. 2024;10(3):28-31. 
2. Kosinski TF. Layered bone grafting in preparation for dental implants: Management of a maxillary defect with calcium apatite material and particulate allograft. Inside Dentistry. 2022;18(11):32–3.
3. Nappe C, Rezuc A, Montecinos A, et al. Histological comparison of an allograft, a xenograft and alloplastic graft as bone substitute materials. J Osseointegration. 2016;8(2):20–6. doi:10.23805/jo.2016.08.02.02
4. Kosinski TF. Socket grafting and implant placement: A simplified approach. Chairside Magazine. 2023;18(2):32–9.
5. Valen M, Ganz SD. A synthetic bioactive resorbable graft for predictable implant reconstruction: Part 1. J Oral Implantol. 2002;28(4):167–77. doi:10.1563/1548-1336(2002)028<0167:ASBRGF>2.3.CO;2
6. Ganz SD, Valen M. Predictable synthetic bone grafting procedures for implant reconstruction: Part 2. J Oral Implantol. 2002;28(4):178–83. doi:10.1563/1548-1336(2002)028<0178:PSBGPF>2.3.CO;2
7. Jones K, Williams C, Yuan T, et al. Comparative in vitro study of commercially available products for alveolar ridge preservation. J Periodontol. 2022;93(3):403–11. doi:10.1002/JPER.21-0087
8. Kosinski TF. Replacement of a maxillary first molar: Extraction, socket grafting and sinus lift. Chairside Magazine. 2022;16(3):49-55.
9. Artzi Z, Nemcovsky CE, Tal H, et al. Histopathological morphometric evaluation of 2 different hydroxyapatite-bone derivatives in sinus augmentation procedures: a comparative study in humans. J Periodontol. 2001;72(7):911–20. doi:10.1902/jop.2001.72.7.911
10. Kosinski TF. Bone grafting: Essential indications and techniques in implant dentistry. Chairside Magazine. 2017;12(2):67-74.
11. Kosinski TF. Sinus tenting for posterior maxillary implant placement. Dent Today. 2014;33(8):58-61.
12. Cheon KJ, Yang BE, Cho SW, et al. Lateral window design for maxillary sinus graft based on the implant position. Int J Environ Res Public Health. 2020;17(17):6335–45. doi:10.3390/ijerph17176335
13. Zitzmann NU, Schärer P. Sinus elevation procedures in the resorbed posterior maxilla. Comparison of the crestal and lateral approaches. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 1998;85(1):8-17. doi:10.1016/s1079-2104(98)90391-2
14. Cho SW, Yang BE, Cheon KJ, et al. A simple and safe approach for maxillary sinus augmentation with the advanced surgical guide. Int J Environ Res Public Health. 2020;17(11):3785. doi:10.3390/ijerph17113785
15. Thomas M, Akula U, Ealla KK, et al. Piezosurgery: A boon for modern periodontics. J Int Soc Prev Community Dent. 2017;7(1):1-7. doi:10.4103/2231-0762.200709
16. Pereira CC, Gealh WC, Meorin-Nogueira L, et al. Piezosurgery applied to implant dentistry: clinical and biological aspects. J Oral Implantol. 2014;40:401–8. doi:10.1563/AAID-JOI-D-11-00196

ABOUT THE AUTHORS

Dr. Tilley received her DMD degree from the University of Alabama School of Dentistry. She is a native of Pensacola, Fla, and has been practicing dentistry in her hometown since 1998. She keeps up with the latest in dentistry by attending continuing education seminars on topics such as oral surgery, implants, veneers, periodontal disease, cosmetic procedures, and much more. Dr. Tilley has also done extensive training at the Las Vegas Institute for Advanced Dental Studies and the Engel Institute with Drs. Timothy Kosinski and Todd Engel, respectively. She is a Fellow of the International College of Dentists (ICD) and is a member of the AGD, the ADA, the Florida Dental Association, the Alabama Dental Association, the Academy of Laser Dentistry, and the Academy of American Facial Esthetics. Dr. Tilley has received Fellowships with the International Congress of Oral Implantologists (ICOI) and the ICD. Most recently, Dr. Tilley was inducted into Fellowship in the Academy of Dentistry International and the American College of Dentists. She can be reached at stephflynntilley@cox.net.

Dr. Kosinski received his DDS degree from the University of Detroit Mercy School of Dentistry (Detroit Mercy Dental) and his Mastership in biochemistry from the Wayne State University School of Medicine. He is an affiliated adjunct clinical professor at Detroit Mercy Dental; serves on the editorial review board of REALITY, the information source for aesthetic dentistry; and is the past editor of the Michigan Academy of General Dentistry Update. He is currently the editor of the AGD journals General Dentistry and AGD Impact and is the editor of Implants Today in Dentistry Today. He is a past president of the Michigan AGD. He is a Diplomate of the American Board of Oral Implantology/Implant Dentistry, the ICOI, and the American Society of Osseointegration. He is a Fellow of the American Academy of Implant Dentistry and received his Mastership in the AGD. He can be reached at drkosin@aol.com.

Disclosure: The authors report no disclosures.