and Mg-e HA/collagen-based scaffold

Sinus lift in severely resorbed maxillae: One-year follow-up

Abstract

Objective

Luigi Canulloa The aim of this prospective study was to clinically analyze the behavior of implants inserted into severely resorbed maxillae after sinus grafting. a Private practice, Rome, Italy

Materials and methods Corresponding author:

Dr. Luigi Canullo Twenty-six wide-diameter implants with a rough surface over their entire Via Nizza 46 length were inserted during 13 consecutive sinus lifts. Radiographic 00198 Rome analysis was preoperatively requested for each patient. After Schneiderian Italy membrane elevation, a magnesium-enriched hydroxyapatite (Mg-e HA) T +39 06 8411980 and collagen-based scaffold with a porous 3-D structure was used to [email protected] prevent perforation during implant placement. Sinus grafting was per- formed using a biomimetic Mg-e HA. No membrane was used to cover How to cite this article: the buccal window. The preoperative residual bone height ranged

Canullo L. Sinus lift surgery in severely resorbed between 1 and 4 mm (mean value: 2.5 mm; SD: 1.0 mm). maxillae: one-year follow-up. J Oral Science After 6 months of healing, uncovering was carried out and the defin- Rehabilitation. 2018 Mar;4(1):08–14. itive restoration was seated after 2 weeks. In order to monitor the stabil- ity changes, resonance frequency analysis was performed and ISQ (Implant Stability Quotient) values were collected at the first surgery (baseline,

T0), at the abutment connection (T1) and at the 1-year follow-up (T2). In order to measure bone changes, the patients underwent panoramic radiographs after 2-year follow-up. Image analysis software calculated the grafted bone height changes at the level of the implant site, compar- ing preoperative and follow-up panoramic radiographs.

Results

No postoperative complications were observed. The mean ISQ value was

42.5 (SD: 2.7) at T0, 75.3 (SD: 8.2) at T1 and 81.5 (SD: 2.6) at T2. Statisti- cally significant differencesP ( ≤ 0.005) regarding mean ISQ values were

found between T1 and T0, as well as between T1 and T2. After 12 months of functional loading, only 1 implant was lost (cumulative survival rate: 96.15%). During the same observation period, the mean radiographic vertical height of the grafted sinus floor was 11.05 mm (SD: 2.10 mm), with a mean gain of 8.50 mm.

Conclusion

Within the limitations of this study, despite preoperative critical residual bone height, lift restoration using a biomimetic Mg-e HA and an Mg-e HA/collagen-based scaffold with a porous 3-D structure seems to be a reliable procedure.

Keywords

Sinus lift, magnesium enriched hydroxyapatite, x-ray analysis, ISQ.

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Introduction restoration in the posterior maxilla with a sinus augmentation procedure. A total of 26 wide-­ Sinus floor augmentation has recently become a diameter implants with a rough surface over widely accepted surgical procedure to improve the their entire length were inserted in extremely amount of bone volume before implant placement. resorbed posterior maxillae. The present study Although the use of autogenous bone appears to was performed following the principles outlined be the gold standard,1, 2 much attention has been in the Declaration of Helsinki of 1975, as revised paid to the use of bone substitutes. After the har- in 2013, on experimentation involving human vesting procedure, donor site morbidity has to be subjects. All of the patients were in general taken into consideration.3 Additional disadvan- good health. They were informed about the pro- tages for autografts are the limited availability and cedure and required to sign a consent form. the tendency to resorb.4 In order to overcome these They were followed for a period of 12 months limitations, several biomaterials have been evalu- after prosthetic rehabilitation. The principal ated in experimental and clinical studies, such as inclusion criterion was a residual bone crest demineralized freeze-dried bone allograft,5 bovine (distance between the sinus floor and bone bone matrix,4 composite bone graft including crest) ranging between 1 and 3 mm in height platelet-rich plasma,6 resorbable and nonresorb- and allowing wide-diameter implant insertion. able hydroxyapatite7, 8 and beta-tricalcium phos- Additional inclusion and exclusion criteria are phate.9 In particular, bioceramics based on calcium summarized below: phosphate are widely used owing to their biocom- patibility, absence of immunogenic factors and Subject inclusion criteria: osteoconductivity; although, the high temperature ––Need for fixed implant-supported prosthesis during the sintering process could negatively influ- in the posterior maxilla. ence osteoconductivity and resorption time.10 New ––Aged > 18 years. hydroxyapatites enriched with magnesium (Mg-e ––No relevant medical conditions. HAs) have recently been introduced on the market. ––Nonsmoker or smoked ≤ 10 cigarettes/day Mg-e HA has been demonstrated to allow com- (pipe or cigar smokers were excluded). plete healing of the tissue around a graft and ––Full-mouth plaque score and full-mouth undergoes almost complete resorption already bleeding score of ≤ 25%. after 1 year.11 Despite its high predictability, the more recent literature has highlighted possible Study site inclusion criteria: complications after this procedure.12 The main ––Native bone height of 1–3 mm in the sinus zone. complication is membrane perforation, mostly during implant insertion. Mg-e HA/collagen-based Subject and site exclusion criteria: scaffolds have been successfully used for sinus ––Acute infection of the augmentation procedures, demonstrating bone or chronic sinusitis. formation after 6 months already.13 Owing to its ––Allergies involving the respiratory system. properties, this material might be suitable to pro- ––A history of bisphosphonate therapy. tect the sinus membrane from eventual perfora- ––Uncontrolled diabetes (glycated hemoglobin tion during implant insertion. A1c > 6%, glycemic level > 110 mg/dL). The present preliminary prospective study was designed to evaluate clinically and radiologically Preoperative and implant restorations 12 months after prosthetic postoperative medication loading in severely resorbed maxillae requiring 1-stage sinus lift surgery. The graft used was an The patients underwent a preoperative digital Mg-e HA and Mg-e HA/collagen-­based scaffold , subsequently used as with a porous 3-D structure and was used to pre- baseline. A cone beam computed tomography vent Schneiderian membrane perforation. scan was also required to investigate antral anat- omy (Fig. 1). One week before the surgical pro- Materials and methods cedure, full-mouth professional prophylaxis was performed. The patients were instructed to use Study design and patient selection 1 g of penicillin clavulanate 1 day prior to surgery and continue with 2 g per day for 6 days. Just One dental center consecutively recruited before surgery, the patients underwent a 5-min 13 patients scheduled for implant-supported mouth rinse with 0.2% gluconate.

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Fig. 1A Figs. 2A–C Figs. 1A & B Preoperative digital panoramic radiograph with preoperative computed tomography scans.

Figs. 2D–F

A

Fig. 1B

B

Surgical technique at the superior aspect of the sinus and against the medial aspect of the grafted compartment The sinus area was prepared under local anes- created in the sinus cavity. The graft material thesia, as described by Boyne and James.1 The was meticulously condensed at each stage. bony window was left attached to the Schneide- Then, 2 implants (5 mm in diameter, 10–13 mm rian membrane. The sinus mucosa was elevated, in length, Premium SP, Sweden & Martina, Due taking care to avoid laceration. In all cases, an Carrare, Italy) were placed at a torque value of Mg-e HA/collagen-based scaffold with a porous > 10 Ncm. The root-shaped implant used in this 3-D structure (RegenOss, Finceramica, Faenza, study had a sandblasted and acid-etched sur- Italy) was used to protect the Schneiderian mem- face over its entire length. No membrane was brane and prevent any mechanical complication used to cover the buccal window (Fig. 2). The during grafting and implant insertion. oral mucosa was then sutured with 5-0 resorb- Implant sites were marked using a surgical able interrupted sutures (Vicryl, Ethicon, New template. In order to increase primary stability, Brunswick, N.J., U.S.). osteotomies were performed using the narrow- est drill able to allow implant insertion, to avoid Postoperative treatment buccal bone fracture. Residual bone height was assessed using a modified probe with a small The patients were instructed to avoid blowing hood. Then, the graft material (HA granules, their noses for at least 7 days after surgery and 600–900 μ, SINTlife, Finceramica) was placed to cough or sneeze with an open mouth to prevent

10 Volume 4 | Issue 1/2018 Journal of Oral Science & Rehabilitation Sinus lift and Mg-e HA/collagen-based scaffold

Fig. 1A Figs. 2A–C

A B C

Figs. 2D–F

Fig. 1B D E F

increased pressure in the operated sinus. They Implant stability measurements underwent a new digital panoramic radiograph for postoperative evaluation. Clinical and surgical Immediately after implant insertion (baseline,

postoperative complications were measured. T0), resonance frequency analysis (RFA; Osstell Mentor, Osstell, Gothenburg, Sweden) for each Second-stage procedure and implant was carried out and the values were Figs. 2A–F follow-up evaluation used as baseline. The transducer was hand- (A) Following the limits of the screwed into the implant body as recommended sinus, a bone window was outlined along the sinus edge Second-stage surgery to expose the implants by manufacturer. The RFA value is represented with a round diamond bur was performed 6 months after implant place- by a quantitative parameter called ISQ (Implant (2,000 rpm) under copious ment. After performing a minimal crestal inci- Stability Quotient). The ISQ ranges between irrigation. (B) The sinus mucosa was sion just over the area corresponding to the 1 and 100. The measurements were repeated for elevated, taking care to avoid laceration, and RegenOss implant, the cover screws were exposed and each implant after 6 (T1) and 12 months after was inserted to protect the removed. Attached keratinized mucosa was left prosthetic loading (T2). Each measurement was membrane during insertion on both the palatal and buccal aspects around taken twice buccolingually and the mean value of the graft material. all of the implants, and healing abutments were was used. Because each transducer had a unique (C) An Mg-e HA collagen- based scaffold was elevated screwed in at a torque of 10 Ncm. fundamental RF, the measurements were cali- to allow particulate graft Clinical evaluation criteria at the time of brated using a calibration block. All stable material to fill the sinus cavity. (D) SINTlife graft material implant exposure included stability in all direc- implants were considered successful. was compacted in the sinus tions, eventual crestal bone resorption, and any cavity. reported pain or discomfort. One week later, Complications (E) Implants were inserted. Final step of the surgery: after impression taking using pickup coping No membrane was used. transfers, titanium abutments were screwed in Any technical (implant fracture, screw loosen- Implant insertion. at a torque of 32 Ncm. In the same procedure, ing, etc.) and/or biological (pain, swelling, sup- (F) Final filling of the sinus cavity. an additional impression of the screwed-in abut- puration, etc.) complications were considered. ment was taken using the metallic structure. The provisional restoration was seated. In order Radiographic evaluation to allow better distribution of the occlusal forces, splinted crowns were used. Implants The grafted area was evaluated with a comput- inserted in residual neighboring bone without erized measuring technique applied to the digital augmentation were not splinted to the ones panoramic radiographs (preoperative and inserted in augmented bone. One week later, 12-month follow-up). In each case, the surface definitive crowns were cemented using a provi- of grafted sinus was marked with a virtual mark- sional cement (Temp-Bond, Kerr, Orange, Calif., ing instrument. An image analysis software pro- U.S.) Twelve months after prosthetic loading, a gram (AutoCAD 2006, Version Z 54.10, Autodesk) digital panoramic radiograph was obtained to calculated the total (native + grafted) bone assess the newly formed bone and its interface height changes at the level of the implant site, with the implant (Fig. 3). comparing preoperative and follow-up

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Fig. 3 Fig. 3 Digital panoramic radiograph 12 months after prosthetic loading.

panoramic radiographs, with the ability to com- was substituted with an implant 6 mm in diam- pensate for eventual radiographic distortion.14, 15 eter at the same surgical stage and restored All measurements were conducted and recorded after an additional 3 months of healing. All of by the same trained independent examiner, with- the other implants were osseointegrated after out input from the implant surgeon. 12 months of prosthetic loading (cumulative survival rate: 96.15%).

Statistical analysis The mean ISQ value was 42.5 (SD: 2.7) at T0,

75.3 (SD: 8.2) at T1 and 81.5 (SD: 2.6) at T2. Sta- Descriptive statistics, including mean values and tistically significant differencesP ( ≤ 0.0005) standard deviation, were used to describe regarding mean ISQ values were found between

changes in implant stability over the time and T1 and T0, as well as between T1 and T2. The mean bone area. Student’s t-test for paired data was radiographic vertical height of the grafted sinus performed to test the significant difference floor was 13.75 mm (SD: 1.30 mm) after

between ISQ values at T0, T1 and T2. Student’s 12 months of prosthetic loading (P ≤ 0.0005). t-test was used to perform bone area compari- son. Significance was set atP > 0.05. Discussion

Results This prospective study demonstrated that, even in critical conditions, and longi­ A total of 13 consecutive patients (8 females and tudinal stability of implants with a rough surface 5 males) were treated. The mean age was over their entire length could be a reliable clinical 62.1 years (SD: 11.05 years). No patient dropped outcome when placed in maxillary sinuses out during the study. The preoperative mean grafted with a biomimetic Mg-e HA. Additionally, residual bone level was 2.5 mm (SD: 1.0 mm). the use of an Mg-e HA/collagen-based scaffold Minimal perforation of the sinus membrane with a porous 3-D structure seems to prevent occurred in 4 cases. The healing period after surgical complications due to microperforation sinus augmentation was without complication of the Schneiderian membrane. for all of the patients. Minor nosebleeds The main limitations of the present study occurred in 1 case. No clinical symptoms of max- were the short-term follow-up (1 year) and small illary sinusitis occurred in any patient. Only sample size (13 patients). However, this study is 1 implant was mobilized during the uncovering a preliminary report proving the feasibility of the procedure, in a light smoker. For the failed combination of an Mg-e HA/collagen-based implant, the preoperative height was 2 mm, the scaffold with a biomimetic HA. Additionally, the

ISQ value was 39 at T0 and 42 at T1. The patient absence of a control group does not allow for did not report any symptoms during the healing demonstration of any additional benefit com- period. After surgical , the implant pared with the gold standard in sinus lift surgery.

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Fig. 3 The graft material investigated in this study was unknown, and it is probably due to membrane a new generation of HA, biomimetic scaffolds, compression from the graft shifting subsequent and was studied as an alternative to overcome to the implant insertion.12 the disadvantages of conventional graft mate- In order to prevent this complication, an rial, simulating bone structure not only from a Mg-e HA/collagen-based scaffold with a porous chemical point of view, but also microscopically, 3-D matrix was placed between the sinus mem- reproducing micropores and their interconnec- brane and the graft. The clinically relevant pecu- tions. Within this graft material category, liarity of this scaffold is its appearance, which is Mg-e HAs have chemical and morphological similar to that of a collagen membrane, and properties close to that of natural bone and have therefore its similar elasticity. The scaffold was showed comparable results to autologous bone advantageous, preventing perforation of the in regenerative procedures. This configuration sinus mucosa by the graft material particles. At seems to be able to induce migration, adhesion the same time, the scaffold acted as not only a and proliferation of osteoblasts inside the pore membrane but, as demonstrated by the litera- network and to promote angiogenesis inside.11 ture,13 also a graft material itself. From a surgical A recent literature review showed the point of view, despite very resorbed maxillae, no residual bone crestal height to be one of the postoperative problems or complications were most critical factor influencing implant sur- observed when implants were inserted simul- vival rate. At the same time, a minimum bone taneously with the graft material. Although the height of 4–5 mm is recommended for a literature describes problems during the surgical 1-stage implant insertion.16 However, accord- phase in sinus augmentation in patients with ing to Peleg et al., despite severely resorbed 1–4 mm residual bone height,23 the use of maxillae, a 1-stage surgical technique was wide-diameter implants allows a sufficient pri- adopted in the present study.17 mary stability.24

This approach finally reported only 1 implant Although the mean value of ISQ at T0 was

failure, according to the results obtained by very low, the data reported at T1 are in line with Fugazzotto and Vlassis18 in their retrospective that of previously reported findings. In fact, Lai report and according to Wallace and Froum19 et al. reported the same findings for rough-­ and Del Fabbro et al.16 in their reviews. Further- surfaced implants installed after minor sinus more, in their systematic review, Wallace and floor elevation.25 Froum indicated membrane placement over the The statistically significant increase of ISQ

lateral window to be an important factor to values between T0 and T1 could be evidence of improve the quality of regenerated bone.19 An fast maturation of the graft, after just 3 months.

absorbable collagen membrane placed on the An additional increase between T1 and T2 could buccal sinus wall, in fact, seemed to protect the indicate a further maturation of the material graft from soft-tissue invasion, which would after 12 months of prosthetic loading. Despite reduce the amount and the quality of the some clinical studies suggesting positive results de novo-­formed mineralized tissue.20, 21 This find- with the use of RegenOss alone in sinus lift pro- ing was also confirmed by a published system- cedures after 6 months,12 controversial out- atic review.22 In this study, Pjetursson et al. comes with the use of a soft matrix were reached showed an annual implant failure rate signifi- in the literature.26 In fact, Caneva et al. sug- cantly higher (4.0% vs. 0.7%) when no mem- gested the use of rigid materials to counteract brane was used to cover the lateral window after negative pressure during respiration.26 the grafting procedure.22 Results from the present study showed that a membrane may not be a critical factor for the Conclusion implant survival rate. An additional result to be noted is the absence of any postsurgical com- The present study, within its limitations, demon- plication in the case of microperforation of the strated that the use of a soft matrix in associa- membrane. In fact, sinus membrane perforation tion with a graft material allows bone regener- is a typical surgical complication. This event ation without postoperative complications. could occur during membrane elevation before However, further studies should aim to measure graft insertion or after graft insertion at the time discrepancies between preoperative and long- of implant positioning. According to the litera- term postoperative increments using the prom- ture, the second possibility is often clinically ising matrix used in the present study.

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