Indirect Sinus Lift Done Using "Autogenous Core Lift" Technique in Combination with Alloplastic Phosphosilicate Putty in Atrophic Maxillary Posterior Region: A Clinical Report with 1-Year Follow-Up.

Pneumatization of the sinus is a common occurrence after extraction of maxillary posterior teeth. Implant procedures require a clinically acceptable level of bone to be present for implants to be placed in function. Residual bone with >4 mm of height can be managed using the indirect sinus lift procedure, whereas bone height <4 mm requires a direct sinus lift using lateral window approach. This clinical case report describes the use of autogenous core used to lift the membrane in conjunction with calcium phosphosilicate putty using minimal armamentarium, thereby avoiding the associated morbidity and complications associated with a direct sinus lift procedure.

Introduction

Maxillary sinus augmentation is a common clinical procedure performed in the posterior maxilla and is one of the important factors affecting implant success in that region. Following tooth extraction, the resorption rate is highest in the initial 6 months, affecting the width and height of the ridge and compromising future implant placement.[1] Insufficient bone height is one of the primary factors affecting implant placement in the posterior maxilla.[2] Previous studies attribute implant failures in the maxillary posterior region to the poor quality of bone (Type IV).[345] Loss of teeth can result in the absence of functional loading which can result in severe bone resorption, thinning down the walls as a consequence causing pneumatization of the sinus.[6] This leads to compromise in future implant placement and necessitates additional surgical procedures to augment bone.

Traditionally, lateral window and indirect sinus lift procedures have been proposed to facilitate implant placement and have been used with varying degrees of success.[78910] Fugazzotto advocated an alternative approach to sinus augmentation, using a trephine core along with osteotomes.[11] When residual bone height was 4–5 mm in the posterior maxilla, he proposed that using a trephine created less trauma when compared to traditional indirect sinus lift procedure. In addition, the technique conserved autogenous bone and minimized the risk of perforation in sinus membrane by avoiding a 2-mm pilot twist drill to begin the osteotomy.[111213] Fugazzotto found higher success rates with this approach in comparison to the lateral approach.[14] Maxillary molar extraction sites were found to have a 96%–97.8% success rate for implants in function for a 3-year follow-up.[151617] Kolerman et al. showed an 11-year 100% survival rate for implants placed in the maxillary posterior region using this technique.[18] The proposed modifications to the trephine core technique allow for implant site development in the posterior maxilla in both single and multiple edentulous sites. Fugazzotto previously demonstrated the technique for immediate implant placement at a maximum length of 8.5 mm.[11] The authors have attempted to further develop single and multiple sites to allow for longer length implants. In comparison to 8-mm long implants, implant lengths >10 mm have had a more favorable cumulative success rate (88.9% vs. 93.4%) with internal sinus lift procedures.[19]

Indications and contraindications for sinus augmentation

The following are indications for sinus augmentation:[20]

No history of sinus pathosis

Insufficient residual bone height (<10 mm of bone height)

Severely atrophic maxilla

Poor bone quality and quantity in the posterior maxilla.

Sinus augmentation is not indicated when the patient has the following history:

Recent radiation therapy in maxilla

Uncontrolled systemic diseases such as diabetes mellitus

Acute/chronic maxillary sinusitis

Heavy smoker

Alcohol abuse

Psychosis

Severe allergic rhinitis

Tumor or large cyst in the maxillary sinus

Oroantral fistula.

Surgical procedure

Preoperative radiographic measurements are made to evaluate residual bone height at the site of future implant placement. In edentulous sites, a crestal incision is used [Figure 1]. Vertical releasing incisions are made on the buccal tissue to allow flap advancement. A full-thickness flap is elevated to gain sufficient access to the site. A calibrated trephine bur is then used to create a core. A silicone stopper is used to mark the depth of entry on the trephine. The trephine must be marked to stop approximately 0.5 mm short of the sinus floor. The trephine core should be a minimum 2 mm less than the buccopalatal width, ensuring 1 mm of bone on each side. To achieve good contact with the alveolar crest without slipping, the trephine is first used in reverse to engage bone, and then forward to continue drilling.[18] Maximum cutting speed can be in the range of 1200–1500 rpm. Once the trephine core is completed, the lateral walls are free from bone, while the core remains attached to the floor of the sinus. A calibrated osteotome is chosen, corresponding to the diameter of the trephine preparation. The osteotome is used with gentle malleting forces to push the core to the required depth of the prepared site. If cone–beam computed tomography (CBCT) confirms a thick Schneiderian membrane, it has been reported that you can gently mallet beyond the overlapped area.[20] Once the desired height is achieved, the osteotomy is gently packed with phosphosilicate putty graft material. An implant of diameter slightly more than the trephined site is chosen and is tapped in. The implant must be a little wider to achieve an initial primary stability. It is then covered with a resorbable collagen membrane with tacks placed to stabilize the same. In cases where primary closure is not attainable, a nonresorbable dense polytetrafluoroethylene (PTFE) membrane can be utilized.[21] Once the membrane is stabilized, mucoperiosteal flaps are replaced and sutures placed to achieve primary closure. The healing period ranges from 3 to 6 months. If implants have not been placed during the initial surgery, at the time of reentry, implant placement is accomplished by conventional drilling. A tapered implant is recommended for increased stability,[22] especially in areas of decreased bone density.

Figure 1

Surgical site (preoperative)

Clinical Report

A 36-year-old female patient reported to the clinic with missing 26 and was willing to undergo replacement with implant supported prosthesis. The patient was in sound systemic health, and biochemical investigations revealed no apparent problems. CBCT analysis revealed that the region of interest showed residual bone height to be around 4 mm [Figure 2]. As the patient did not want to undergo an elaborate surgical procedure of direct sinus lift, the autogenous core lift technique was used. The patient was prepared for surgery, and prophylactic antibiotic coverage was given (2 g amoxicillin, 1 h before surgery) as recommended by Esposito et al.[23]

Figure 2

Preoperative cone–beam computed tomography image of the site

The crestal incision was placed and full-thickness flap was elevated. The buccal and palatal flaps were adequately mobilized to provide a clear field of the alveolar crest. A 4-mm calibrated trephine was selected, and a silicone stopper was placed at the desired stop, 0.5 mm short of the sinus floor. The bone was trephined to the predetermined depth, and the 4-mm osteotome was used to tap the autogenous core into the sinus using gentle malleting force [Figure 3]. At every 3-mm intervals of the core being tapped, phosphosilicate putty (novabone) [Figure 4a] was used into the osteotomy, and the tapping was then progressed until the desired depth of 10 mm was achieved [Figure 4b]. A tapered implant of suitable diameter and length (4.2 mm × 10 mm) was then chosen and was motor driven into the osteotomy till the crestal level [Figure 4c]. Primary stability of 25 mm was achieved as shown by the physiodispenser. The cover screw was placed. Flaps were sutured using 3.0 Vicryl to achieve tension-free primary closure. Postoperative radiographs were recorded [Figure 5]. A 500-mg dose of amoxicillin was prescribed 3 times/day for 5 days postoperatively. Ibuprofen (600 mg) was prescribed as needed. The patient was instructed to use 0.12% chlorhexidine gluconate rinse twice daily for 10 days. A soft diet and appropriate oral hygiene were recommended for 2 weeks. Sutures were removed 14 days after the surgical procedure. The postoperative recovery was uneventful. The patient was examined clinically and radiographically each week in the 1st month after surgery and twice a month in the subsequent 2 months. The healing process was uneventful. A metal ceramic cement retained crown was placed after a period of 6 months after clinical and radiographic evaluation [Figure 6a]. The patient was followed-up over a year after the procedure with clinical and radiographic evaluation [Figure 6b], and the evaluated parameters were found to be within acceptable limits.

Figure 3

Surgical site after trephination

Figure 4

(a) Phosphosilicate putty used (novabone). (b) Indirect sinus lift performed using osteotomes. (c) Implant placement completed

Figure 5

Postimplant placement IntraOral PeriApical Radiograph (IOPA). Sinus lift can be clearly seen in the X-ray

Figure 6

(a) Postprosthetic loading at 4 months. (b) IOPA at 1-year follow-up

Discussion

Indirect sinus lifts are commonly performed to correct deficient bone vertically to ensure optimal length of implant in the posterior maxilla. The lateral approach direct sinus lift procedures have been successful but have limitations such as it has higher morbidity, is time-consuming, and also is more invasive. It also demands a higher level of expertise on the operators part and is more demanding when adjacent teeth are present. The risk of membrane perforations and postoperative complications are also higher.[24] Although less invasive indirect sinus lift procedures have been proposed, this autogenous core lift enables a distinct advantage as it augments the sinus and also allows for simultaneous implant placement, thereby reducing another surgical procedure and shortening treatment duration. Kolhatkar et al.[25] reported a 97.0%–97.1% success rate for the implant placed in the sinus lift area with a crestal approach. Another distinct advantage that this procedure provides is the autogenous “bone bed” below the apex of the implant, which ensures that there is vital bone surrounding implant on three sides around the implant. The addition of alloplastic phosphosilicate putty ensures complete fill in the interstices around the core and the sinus membrane. The bone putty material is osteoconductive and facilitates new bone formation around it and incorporating itself in the newly formed bone. Alloplastic phosphosilicate putty has shown to form vital bone volume and content at 4- to 6-month period with shorter healing time and good tissue compatibility.[26] A viable autograft core in conjunction with phosphosilicate putty is expected to yield superior results. Although membrane perforation is a potential possibility with this technique, the advantages far outweigh the potential for complications. This technique negates the requirement for conventional osteotomy, preserves bone, and, in conjunction with simultaneous implant placement, also reduces treatment duration compared to conventional indirect sinus lift procedures. To prevent perforation of the sinus membrane, Nkenke et al.[27] suggested that the sinus lift be limited on average to 3.0 ± 0.8 mm using the osteotome technique. The antral membrane balloon elevation technique was introduced by Soltan et al.[28] This is another minimally invasive technique to elevate the sinus membrane but requires specific and specialized armamentarium. The minimally invasive transcrestal sinus approach by Kher et al.[29] advocates using the hydraulic pressure exerted by the calcium phosphosilicate putty to elevate the sinus membrane after the initial osteotomy using the Summers’ technique. Although this technique has distinct advantages as the atraumatic elevation of the sinus lining, the putty is in contact with the apical aspect of the implant as well as the membrane which could lead to an eventual loss of bone volume overtime. Autogenous core lift technique scores over the above-mentioned techniques as there is an autogenous core of bone at the apical aspect of the implant, thereby reducing the requirement for bone grafts and also maintaining the bone volume at the apical aspect of the implant.

The limitations of this technique are the use of trephines which have a high probability of membrane perforation in the hands of the inexperienced operators. It also necessitates the accurate evaluation of the residual bone volume using newer radiologic evaluative methods such as CBCT which may not be readily available. Furthermore, long-term studies have not been reported about this technique regarding bone volume stability over longer periods.

Conclusion

The autogenous core lift technique in conjunction with alloplastic calcium phosphosilicate putty and osteotomes allows for atraumatic indirect sinus lifts, thereby providing greater bone volume and stability in the posterior maxilla for predictable implant therapy. A 1-year follow-up showed stable bone volume in the periimplant area.

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

Nil.

Conflicts of interest

There are no conflicts of interest.