Sequential Bone Repair in Rabbit Sinus Lifts Using Bio-Oss and Hyaluronic Acid-Polynucleotide Gel (Regenfast)

BACKGROUND

A comprehensive investigation to associate the use of polynucleotides and hyaluronic acid with bovine bone in maxillary sinus lift procedures in rabbits has not been performed yet. The aim was to evaluate the influence of this novel association on the processes of bone regeneration in maxillary sinus augmentation.

METHODS

In this prospective, randomized, within-animal model, maxillary sinus augmentation was performed bilaterally in 12 rabbits. Deproteinized bovine bone material (DBBM) was used as filler material. A hyaluronic acid-polynucleotide gel was aggregated at the test site. Histological evaluations were performed after 2 and 10 weeks of healing.

RESULTS

After 2 weeks of healing, similar amounts of new bone were observed at both the control (7.7 ± 4.3%) and test sites (8.1 ± 3.8%; p = 0.697). Bone formation was observed predominantly along the osteotomy margins and adjacent sinus walls. After 10 weeks of healing, the total new bone fraction reached 28.0 ± 10.1% at the control sites and 27.3 ± 10.5% at the test sites (p = 0.563). Multiple perforations of the sinus mucosa were observed in both groups when in contact with the biomaterial granules.

CONCLUSION

The present study failed to demonstrate a positive effect on bone formation when incorporating hyaluronic acid-polynucleotide gel (Regenfast) into a xenograft for maxillary sinus augmentation. Additionally, the use of this gel did not mitigate the occurrence of thinned mucosa or reduce the risk of subsequent sinus mucosa perforation.

Healing Patterns of Non-Collagenated Bovine and Collagenated Porcine Xenografts Used for Sinus Floor Elevation: A Histological Study in Rabbits

Objective: To compare healing of collagenated and non-collagenated xenografts used for maxillary sinus floor elevation. Materials and Methods: Two different xenografts were used: deproteinized bovine bone (DBBM group) and collagenated corticocancellous porcine bone (collagenated group). Healing was studied after 2, 4, and 8 weeks. The loss of dimensions of the elevated area and the percentages of new bone, xenograft remnants, osteoclastic zones, vessels, inflammatory infiltrates, and soft tissues were analyzed. Three regions were evaluated: close to the bone walls (bone wall region), subjacent the sinus mucosa (submucosa region), and the center of the elevated area (middle region). The primary variables were the percentage of new bone and xenograft remnants. Results: Between 2 and 8 weeks, the elevated areas showed a reduction of 16.3% and 52.2% in the DBBM and collagenated groups, respectively (p < 0.01 between the two areas after 8 weeks). After 8 weeks, the highest content of new bone was observed in the bone wall region, which was higher in the collagenated group than in the DBBM group (41.6% and 28.6%, respectively; p < 0.01). A similar quantity of new bone was found between the two groups in other regions. A higher percentage of vessels in all regions evaluated (p < 0.01) and soft tissue in the sub-mucosa region (p < 0.05) was found in the collagenated group than in the DBBM group. Conclusions: The present study showed that both xenografts allowed new bone formation. In comparison with the non-collagenated xenograft, the collagenated xenograft underwent higher resorption, resulting in greater shrinkage of the elevated space after sinus lifting and a higher content of new bone in the regions close to the bone walls. Clinical relevance: In this study, the region adjacent to the bone wall showed the highest new bone content. This region resembles the base of the sinus, closest to the sinus floor and walls, and is the most important region from a clinical point of view because it is where the implant will be installed. Residues of the biomaterial remained after 8 weeks of healing. Other reports have shown that these biomaterial residues may interfere with the integration of implants.

Contribution to Bone Formation of the Schneiderian Membrane after Sinus Augmentation: A Histological Study in Rabbits

AIM

to evaluate bone formation in close contact with the sinus mucosa after different periods from sinus augmentation and the influence on healing of the presence of an inward dis-placed bone window.

MATERIAL AND METHODS

Eighteen rabbits were included in the experiment. A trap-door technique was applied at the test sites, and the bony window was elevated inward (inward window; IW) together with the sinus mucosa. At the control sites, the bony window was removed before the elevation of the sinus mucosa. The elevated space was filled with deproteinized bovine bone mineral (DBBM) and both access windows were covered with a collagen membrane. Histometric measurements were performed subjacent the sinus mucosa after 2, 4, and 8 weeks of healing.

RESULTS

Very few sinuses presented small percentages of new bone in close contact with the sinus mucosa in the various period examined. The presence of bone in the neighbor areas might have influenced bone formation close to the sinus mucosa. The inward displaced bone window supported bone formation close to the sinus mucosa only in the earliest period of healing, while the bone walls increased their influence over time. The lack of increased new bone percentage over time in the most central regions of the elevated sinus mucosa do not support the hypothesis that the sinus mucosa may express its potential in bone formation. It can be speculated that the new bone found in the intermediate and middle regions of the control sites in the earliest period of healing might be due to residual of bone from the osteotomy.

CONCLUSIONS

Very small amounts of new bone were found subjacent to the sinus mucosa, mostly formed from the bone walls, the inward displaced bone window or from possible bone residues from the osteotomy procedures. The lack of increased new bone percentage over time in the most central regions of the elevated sinus mucosa indicates that the contribution to bone formation provided by the sinus mucosa is limited.

Dual Biosignal-Functional Injectable Microspheres for Remodeling Osteogenic Microenvironment

Bone defect regeneration depends on the population and lifespan of M2 macrophages, which are regulated by dual signals generated by the "physical" spatial configuration of biological tissues and "molecular" chemokines. Herein, inspired by the reprogramming of macrophages, immunoengineered porous microspheres are constructed to accelerate bone repair through the regulation of both "physical" and "molecular" signals. The porous structure of injectable poly (l-lactic acid) (PLLA) microspheres prepared by the microfluidic technique provides a "physical signal" for osteogenic differentiation. Additionally, interleukin (IL)-4-loaded liposomes (Ls) are modified on PLLA microspheres through amide bonds to produce IL-4/Ls/PLLA microspheres, providing a "molecular signal" in stimulating the differentiation of macrophages to M2 type. It is confirmed that IL-4/Ls/PLLA microspheres could induce M2-macrophages polarization and potentiate osteoblast proliferation and differentiation while coculturing with macrophages and osteoblasts in vitro. Besides, IL-4/Ls/PLLA microspheres are proved to promote bone defect regeneration by inducing the conversion of M1 macrophages to M2 through dual biosignal-functional regulation in both the calvaria defect and maxillary sinus defect models. Overall, the immuno-reprogrammed IL-4/Ls/PLLA microspheres achieve the precise immuno-reprogramming of macrophages by dual biosignal-functional regulation. This immune reengineering strategy paves a way for clinical bone defect treatment.

Evaluation of Bone Response to a Nano HA Implant Surface on Sinus Lifting Procedures: Study in Rabbits

The aim of this study was to evaluate the bone response to two different implant surfaces on sinus lift procedures in rabbits. Bilateral sinus lifting with inorganic bovine bone associated with collagen membrane and immediate implantation were performed in 16 rabbits. Custom mini-implants were randomly installed in the prepared sites: one side received a double acid-etched (DAE) surface and the other a nano-hydroxyapatite (NHA) surface. The animals were euthanized 30 and 60 days after surgery, and biopsies were collected for microtomographic and histomorphometric analysis. After 30 days, no intra- and inter-group statistical differences were observed in microtomographic analysis, while at 60 days, bone analysis showed statistically significant differences between groups (p < 0.05) for all the evaluated parameters. Histomorphometric analysis showed, after 30 days, mean % of Bone-to-Implant Contact (BIC) for DAE and NHA of 31.70 ± 10.42% vs. 40.60 ± 10.22% (p > 0.05), respectively; for % of Bone Area Fraction Occupancy (BAFO), mean values were 45.43 ± 3.597% for DAE and 57.04 ± 5.537% for NHA (p < 0.05). After 60 days, mean %BIC and %BAFO for DAE and NHA implants were statistically significant (p < 0.05). The NHA surface showed superior biological features compared to the DAE treatment, promoting higher bone formation around the implants in an experimental model of bone repair in a grafted area.

Clinical and Histological Healing after Maxillary Sinus Floor Elevation

Sinus floor elevation is a surgical procedure that allows for the insertion of the implant in the posterior region of the maxilla in case of insufficient volume of native bone. Several studies have reported a high success rate, and this has helped to spread this surgical procedure around the world. The subject has been extensively studied and this could lead researchers to think that no new scientific evidence can be provided. However, new ideas and discoveries show that research never reaches a conclusion, and that new information can be added all the time. This collection aimed to provide new evidence that could be added to daily clinical work and to provide new ideas for future research.

Influence on Implant Bone Healing of a Collagen Membrane Placed Subjacent the Sinus Mucosa-A Randomized Clinical Trial on Sinus Floor Elevation

Background: Perforation of the sinus mucosa is quite a frequent complication that might occur during sinus floor elevation. The perforation is often protected with a collagen membrane to avoid the extrusion of graft particles within the sinus. However, this procedure might hinder the innate osteogenic potential of the sinus mucosa. Hence, the aim of the study was to evaluate the influence of a placement of a collagen membrane subjacent the Schneiderian membrane during sinus floor elevation on implant bone healing. Methods: Twenty volunteers took part in the trial. Ten were randomly included in the group that received a collagen membrane subjacent the sinus mucosa (Mb group), and ten did not receive the membrane (non-Mb group). A collagenated corticocancellous porcine bone was used to fill the elevated space. Six 6 months after the sinus floor elevation, a mini implant was placed transcrestally and retrieved after a further 3 months. Histological analyses were then performed on the full body of the mini implant as well as on its coronal and apical portions. Results: The new bone apposition proportion onto the implant surface was similar in the Mb and non-Mb groups, both in the apical and coronal portions of the mini implants. A lesser amount of graft was found in contact with the surface. New bone density around the mini implants were similar both in the apical and coronal portions. However, a statistically higher proportion of graft particles was found in the Mb group compared to the non-membrane group. Conclusions: The placement of a collagen membrane subjacent the sinus mucosa did not affect bone healing at implants and bone density.

Effectiveness of hydraulic pressure-assisted sinus augmentation in a rabbit sinus model: a preclinical study

OBJECTIVES

To investigate the effectiveness of hydraulic pressure-assisted sinus augmentation (SA) in a rabbit sinus model in terms of radiographical and histological healing.

MATERIALS AND METHODS

Bilateral SA was performed in 12 rabbits. Each sinus was randomly assigned to either a hydraulic pressure-assisted SA (test) or a conventional SA (control) group. Healing periods of 2 and 4 weeks were applied (n = 6 for each week). Healing pattern including newly formed bone (NB) and residual bone substitute material (RM) was analyzed with microcomputed tomographically, histologically, and histomorphometrically.

RESULTS

No sinus membrane perforation was detected in either group. In the microcomputed tomographic analysis, the test group exhibited higher apico-coronal spread of RM compared to the control group (p < 0.05). Particularly, the test group exhibited several masses of NB out of the cluster of RM. Histologically, the test group showed an elongated shape of the augmented space, whereas the control group generally presented a dome shape. Histomorphometrically, the total augmented area and the area of NB (1.32 ± 0.56 vs. 0.84 ± 0.40 mm2 at 2 weeks, 2.24 ± 1.09 vs. 2.22 ± 0.85 mm2 at 4 weeks) were not significantly different between the test and the control groups at both healing periods (p > 0.05).

CONCLUSION

Hydraulic pressure-assisted SA led to new bone formation in the distant areas from the bony access hole, but similar histological healing pattern to conventional SA.

CLINICAL RELEVANCE

Hydraulic pressure-assisted SA is a promising option for treating pneumatized posterior maxilla.

Osteotome-Induced Blood Clot and Subsequent Bone Formation with the Use of Collagen Sponge for Integration of Single Dental Implants into the Atrophied Posterior Maxilla: A Retrospective Follow-Up of 36 Implants after 5 to 13 years

Background

Atrophy of the posterior maxilla as a consequence of tooth loss and sinus pneumatization is a frequent condition encountered in the clinical practice. Prosthetic rehabilitation with implants in these patients often requires some kind of bone regeneration procedure to increase the bone volume.

Aim

The aim of the present retrospective study is to analyze the survival and success rates of a series of implants placed in the atrophic posterior maxilla with a transcrestal osteotome procedure, without placing a bone grafting material.

Materials and Methods

From 2006 to 2014, 36 dental implants (Neoss Ltd., Harrogate, UK) were inserted in 36 patients with at least 4 mm of bone below the maxillary sinus using transcrestal osteotome sinus floor elevation and placement of collagen sponge below the sinus membrane. ISQ measurements were made after implant placement and at abutment surgery after 4 to 6 months. The vertical bone height (VBH) was evaluated in intraoral radiographs taken prior to surgery and in radiographs from annual check-up appointments 5 to 13 years after implant placement. In addition, marginal bone loss (MBL) was evaluated.

Results

One implant was lost after four years of prosthetic loading. The remaining 35 implants showed no complications and were loaded with single crowns after 4–6 months of healing. All 35 implants showed clinical success after 8.5 ± 2.8 years of prosthetic loading (from 5 to 13 years). The vertical bone height was 5.9 ± 1.4 mm at surgery, 9.7 ± 1.1 mm at second surgery after 4–6 months, and 8.3 ± 1.8 at the follow-up at 8.5 ± 2.8 years (from 5 to 13 years). The implant stability registered was 73.2 ± 6.2 ISQ at the surgery and 75.8 ± 3.9 at the second surgery after 4–6 months.

Conclusions

The present long-term follow-up study showed that the crestal approach for sinus floor bone augmentation without additional bone grafting results in predicable bone formation and high implant survival. The osteotome technique is a valid alternative to the more invasive lateral window technique in single cases with a minimum of 4 mm of VBH below the maxillary sinus.

Osteotome sinus floor elevation with concentrated growth factor and simultaneous implant placement with or without bone grafting: a retrospective study

The aim of this study was to compare the clinical effects of osteotome sinus floor elevation (OSFE) combined with concentrated growth factor (CGF) and simultaneous implant placement with or without bone grafting in the maxillary posterior region, where the residual bone height (RBH) was 4-6 mm. A total of 44 patients who underwent OSFE combined with CGF and the simultaneous placement of 60 implants (group A, 31 implants with bone grafting; group B, 29 implants without bone grafting) were included in this retrospective study. The clinical indicators of implants were observed for 24 months. Sinus floor lift height was 6.02 ± 0.99 mm in group A and 5.81 ± 0.72 mm in group B (P = 0.360) after surgery. There was no significant difference in the vertical bone resorption between the two groups at 24 months (P = 0.097). Postoperative pain at 14 days (visual analogue scale) was significantly greater in patients with bone grafting when compared to those without bone grafting (P < 0.001). There was no significant difference in marginal bone loss (MBL) between the two groups (P = 0.707 for MBL during the first 12 months, P = 0.922 for MBL during months 12-24). The implant success rate was 100% with or without bone grafting. The technique of OSFE with CGF, either with or without bone grafting, is safe and reliable in patients with RBH 4-6 mm.

Does new bone formation vary in different sites within the same maxillary sinus after lateral augmentation? A prospective histomorphometric study

OBJECTIVE

The aim of this study was to evaluate histomorphometric outcomes of lateral maxillary sinus augmentation in different areas of the same cavity and to correlate results to bucco-palatal sinus width (SW) and residual bone height (RBH).

MATERIAL AND METHODS

Patients needing maxillary sinus floor elevation (RBH <5 mm) to insert two nonadjacent implants were treated with lateral augmentation using a composite graft. Six months later, two bone-core biopsies (mesial/distal) were retrieved in implant insertion sites. SW and RBH were measured on cone beam computed tomography, and correlations between histomorphometric and anatomical parameters were evaluated by multivariate linear regression analysis.

RESULTS

Twenty patients underwent sinus augmentation, and eighteen were included in the final analysis (two dropouts for membrane perforation). Mean newly formed mineralized tissue percentage (%NFMT) after 6 months in mesial and distal sites was 17.5 ± 4.7 and 11.6 ± 4.7, respectively (p = .0004). Multivariate linear regression showed a strong negative correlation between SW and %NFMT (β coefficient=-.774, p < .0001) and no correlation between RBH and %NFMT (β coefficient =-.038, p = .825).

CONCLUSIONS

The present study confirms that %NFMT after lateral sinus augmentation occurs at different rates in different anatomical areas of the same maxillary sinus, showing a strong negative correlation with SW, whereas no influence of RBH was observed. Clinicians should regard SW as a guide for graft selection and to decide duration of the healing period. Researchers should consider SW as a predictor variable, when comparing regenerative outcomes of different biomaterials by using maxillary sinus as an experimental model.

Sinus Mucosa Thinning and Perforations after Sinus Lifting Performed with Different Xenografts: A Histological Analysis in Rabbits

Background: Experimental studies have shown a progressive thinning and perforations of the sinus mucosa associated with sharpened edges and the cutting projections of graft particles used simultaneously for maxillary sinus augmentation. Hence, the aim of the present study was to evaluate the damaging effects of two different bovine grafts on the sinus mucosa after sinus augmentation. Methods: Twenty New Zealand rabbits received a bilateral sinus lifting using, as fillers, two different types of deproteinized bovine bone in granules, one processed at low temperature (low-T group), and the other at high temperature (high-T group). Thinned mucosa sites (<40 µm) and perforations were evaluated in the sinus mucosa that were in contact with graft granules after 2 and 10 weeks, in ten animals per period. Results: After 2 weeks of healing, the number of thinned mucosa sites was 118 in the low-T group, and 149 in the high-T group (p = 0.191). At the 10-week assessment, the thinned sites increased to 237 and 195 sites, respectively. The numbers of sinus mucosa perforations after 2 weeks were eight and three in the low-T and high-T group, respectively. At the 10-week evaluation, the perforations increased to 19 in the low-T group, and to 14 in the high-T group. Conclusions: The contact with bovine xenografts yielded thinning and perforations of the sinus mucosa. Despite the differences in characteristics and dimensions, no differences were found between the two xenografts in the numbers of thinning mucosa sites and perforations. However, a trend of more events was found in the low-T compared to the high-T group.

Influence of the Use of a Collagen Membrane Placed on the Bone Window after Sinus Floor Augmentation-An Experimental Study in Rabbits

BACKGROUND

We studied the influence on healing of a resorbable membrane covering the osteotomy site after maxillary sinus grafting, evaluated in different regions of the augmented area.

METHODS

Maxillary sinus augmentation was performed in 24 New Zealand rabbits. Osteotomy, 4 × 6 mm, were performed bilaterally. A collagenated cortico-cancellous porcine bone was used to fill the elevated region. A collagen membrane was randomly placed over the osteotomy site on one side (MG), and the other side was left uncovered (NMG). The animals were euthanized after 2, 4, and 8 weeks; and histomorphometric analysis was performed in eight different regions.

RESULTS

New bone percentages were similar in both groups. There were no statistically significant differences. In MG, the overall percentages were 15.6 ± 7.3%, 22.9 ± 6.1%, and 24.9 ± 12.0% after 2, 4, and 8 weeks, respectively. In NMG, the percentages were 11.2 ± 4.5%, 24.1 ± 5.7%, and 24.5 ± 15.7%, respectively. The proportions of new bone in the various regions after 8 weeks were 31 ± 8.9% and 29.9 ± 9.1% in the bone walls region, 25 ± 10.1% and 32.8 ± 9.1% in the submucosa region, 22.6 ± 21.6% and 10.9 ± 11.5 in the middle region, 17.3 ± 14% and 13.4 ± 9.8% in the close-to-window region, and 21.8 ± 11.6%, 19.1 ± 6.4% in the osteotomy region-for MG and NMG, respectively.

CONCLUSIONS

In both groups the greatest amounts of bone formation occurred near to the pre-existing bone walls, followed by the sub-mucosa region. The smallest amounts were found in the close-to-window region, followed by the central region. The placement of a collagen membrane to cover the osteotomy site did not influence the amount of new bone formation after sinus grafting.

Pre-Clinical Models in Implant Dentistry: Past, Present, Future

Biomedical research seeks to generate experimental results for translation to clinical settings. In order to improve the transition from bench to bedside, researchers must draw justifiable conclusions based on data from an appropriate model. Animal testing, as a prerequisite to human clinical exposure, is performed in a range of species, from laboratory mice to larger animals (such as dogs or non-human primates). Minipigs appear to be the animal of choice for studying bone surgery around intraoral dental implants. Dog models, well-known in the field of dental implant research, tend now to be used for studies conducted under compromised oral conditions (biofilm). Regarding small animal models, research studies mostly use rodents, with interest in rabbit models declining. Mouse models remain a reference for genetic studies. On the other hand, over the last decade, scientific advances and government guidelines have led to the replacement, reduction, and refinement of the use of all animal models in dental implant research. In new development strategies, some in vivo experiments are being progressively replaced by in vitro or biomaterial approaches. In this review, we summarize the key information on the animal models currently available for dental implant research and highlight (i) the pros and cons of each type, (ii) new levels of decisional procedures regarding study objectives, and (iii) the outlook for animal research, discussing possible non-animal options.

Argon Bioactivation of Implants Installed Simultaneously to Maxillary Sinus Lifting without Graft. An Experimental Study in Rabbits

Background: The treatment of the surface of titanium implants with argon plasma improved its hydrophilicity and cell adhesion, resulting in higher bone apposition on implant and graft surfaces. The spontaneous perforation over time of the sinus mucosa after sinus augmentation has been documented in experimental studies at both implants and graft particles. The aim of the present study was to evaluate the influence of plasma argon treatment of the implant surface on bone apposition and on the rate of sinus mucosa perforations. Methods: A sinus lifting procedure was performed bilaterally in sixteen rabbits, and implants, either treated with argon plasma or left without treatment (control), were placed simultaneously without grafts. After 8 weeks, histological analyses were carried out. Results: A collapse of the sinus mucosa was observed at all implants. Twenty-four out of thirty-two implants presented sinus mucosa perforations at the apex. Several perforations were also found at the threads. Thinned mucosa sites (width < 40 µm) were found around almost all implants. About 2.6–2.9 mm of the apical regions of the implant did not present signs of osseointegration and about 1.3 mm were exposed to the sinus cavity. No statistically significant differences were found between plasma and control sites. Conclusions: In conclusion, the sinus mucosa was damaged and perforated by direct contact with treated and non-treated implant surfaces. The treatment of the implant surface with argon plasma did not affect the outcomes.

Sinus Mucosa Thickness Changes and Ostium Involvement after Maxillary Sinus Floor Elevation in Sinus with Septa. A Cone Beam Computed Tomography Study

Background: A thickening of the sinus mucosa is observed after sinus floor augmentation. The objective of this retrospective study was to evaluate the influence of the presence of septa in the dimensional variation and ostium involvement over time of the Schneiderian mucosa after sinus floor augmentation. Materials and Methods: Fifteen sinuses with septa (septa group) and 15 without (control group) were selected. CBCTs taken before surgery, and were analyzed after 1 week and after 9 months. Schneiderian membrane thickness changes over time and involvement of the ostium were evaluated. Results: Four perforations occurred in the septa group and none in the control group. After 1 week of healing, the sinus mucosa thickness increased in height by 5.7 mm and 7.1 mm in the septa and control groups, respectively. In this period, the patency of the ostium decreased in both groups, and three infundibula were obstructed in the septa group, and five in the control group. The mucosa was thicker and the edema was closer to the ostium in the control compared to in the septa group. After 9 months of healing, the dimensions regressed to normal pattern and no obstruction of the infundibula were observed. No statistically significant differences were found between septa and control groups. Conclusions: after one week of healing, the sinus mucosa increased in dimensions in both septa and control groups. However, the sinus mucosa presented a tendency of being thicker and closer to the ostium, resulting in a higher number of infundibula obstructions, in the control group compared to in the septa group. After 9 months, the sinus mucosa regressed to normal dimensions and no obstructions of the infundibula were observed in any group.

Influence of Anatomical Parameters on the Dimensions of the Subantral Space and Sinus Mucosa Thickening after Sinus Floor Elevation. A Retrospective Cone Beam Computed Tomography Study

BACKGROUND

Various anatomical parameters might influence the surgical approach for maxillary sinus floor elevation. The objective of the present study was to retrospectively evaluate the influence of anatomical parameters on the dimensions of the subantral space and of the sinus mucosa thickening after sinus floor elevation.

MATERIAL AND METHODS

Seventy-eight maxillary sinuses in sixty-five patients were evaluated on cone beam computed tomographies taken before surgery and after one week (t1w) and nine months (t9m). Several parameters such as the distance XF between an axis parallel to the base of the nose (X-axes) and the sinus floor (F) were correlated with the height gain (IF) at t1w and t9m and the post-surgical edema.

RESULTS

A weak significant positive correlation was observed between height gain vs. sinus height of interest (XF), the balcony, and the sinus floor angle. The post-surgical edema was influenced by the initial mucosa thickness and the xenograft used.

CONCLUSIONS

Various parameters might affect height gain and sinus mucosa thickening after sinus floor elevation. The height of interest, the balcony, and the sinus floor angle showed significant correlations with height gain. The initial thickness of the mucosa and the biomaterial used influenced the post-surgical edema.

Maxillary Sinus Augmentation Using Ceramic Alloplastic Granules or Paste: An Experimental Study in Rabbits

BACKGROUND

Due to the lack of data comparing the biological behavior of two formulations, granules and paste, of alloplastic graft from microtomographic and histomorphometric points of view, the aim of the present experiment was to compare the histomorphometric and microtomographic healing of two formulations, i.e., granules (MR sites) or paste (MR-inject sites) of an alloplastic graft composed of a combination of beta-tricalcium phosphate and hydroxyapatite used for maxillary sinus lifting.

METHODS

A sinus lifting procedure was carried out bilaterally in 20 rabbits, and the elevated space was filled with either paste or granules of an alloplastic material. A collagen membrane was placed on the antrostomy and the animals were euthanized after 2 or 10 weeks, 10 animals each group. Microtomographic and histological analyses were performed.

RESULTS

Higher proportions of new bone formation were found at the MR, compared to the MR-inject sites both after 2 weeks (2.65 ± 2.89% vs. 0.08 ± 0.12%; p < 0.01) and 10 weeks of healing (34.20 ± 13.86 vs. 23.28 ± 10.35%; p = 0.022).

CONCLUSIONS

It was concluded that new bone formation was faster in the MR sites, compared to the MR-inject. However, a longer time of healing should be allowed to make final conclusions about the efficiency in bone formation of the paste formulation of the biomaterial used in the present study.

Osteoconductivity of Bovine Xenograft Granules of Different Sizes in Sinus Lift: A Histomorphometric Study in Rabbits

Background: Due to the lack of data on bone-to-graft contact (BGC) over time in the various regions within the subantral space of the augmented sinus floor, the present study aimed to evaluate the osteoconductivity of deproteinized bovine bone mineral (DBBM) with granules of different sizes applied in maxillary sinus floor elevation. Methods: A maxillary sinus augmentation was performed bilaterally in 18 rabbits using DBBM with particle dimensions of either 0.125–1.0 mm or 1–2 mm. The antrostomy was covered using a collagen barrier. The animals were euthanized in groups of six after 2, 4, and 8 weeks of healing. MicroCT and histological analyses were performed. Results: After 2 weeks of healing, BGC was 10.9% and 11.9% for the small and large granule sites, respectively. After 8 weeks of healing, the BGC increased to 65% and 62% at the small and large granule sites, respectively. The highest values were located close to the bony walls and the bony window. New bone content developed between 2 and 8 weeks from 7.0% to 27.6% and from 6.1% to 27.6% at the small and large granule sites, respectively. Conclusions: Similar outcomes in osteoconductivity and bone formation were found at both small and large DBBM granule sites.

Influence of implant protrusion length on non-grafting osteotome sinus floor elevation with simultaneous implant: a 3- to 9-year retrospective study

BACKGROUND

This study analyzed the influence of implant protrusion length (IPL) on the possible factors that affect the long-term outcomes utilizing non-grafting osteotome sinus floor elevation (OSFE) with simultaneous implant placement, and to explore the optimal range of IPL.

MATERIALS AND METHODS

A retrospective study design was adopted. The clinical and radiographic data of 105 implants in 65 patients were collected after 3-9 (mean 5.04) years follow-up. IPL was divided into three groups (group1, IPL<2mm; group2, 2mm≤IPL<4mm; group3, IPL≥4mm). Endo-sinus bone gain (ESBG), peri-implant marginal bone loss (MBL), bone to implant contact length (BICL), and percentage of ESBG (%ESBG) were used to evaluate non-grafting OSFE. A Kaplan-Meier analysis was performed to assess the cumulative survival rate. Multiple linear regression model was used to explore the relationship between the possible influence factors and ESBG. Analysis of variance (ANOVA) was applied to explore the correlation of IPL with ESBG, MBL, BICL, and %ESBG.

RESULTS

A total of 102 implants in 62 patients fulfilled the survival criteria, giving the cumulative survival rates of 96.4% and 94.1% for implant-based analysis and patient-based analysis, respectively. The mean ESBG, MBL, and BICL at the latest follow-up were 1.95±0.88 mm, 0.58±0.68 mm, and 5.51±1.47 mm. ESBG was found to be positively correlated to IPL. A significant decreased bone formation efficiency was found when IPL was over 4 mm (P=0.02).

CONCLUSIONS

An optimal range of IPL within 4 mm was recommended for better long-term outcomes when applying non-grafting OSFE with simultaneous implant placement.

The effect of anatomy on osteogenesis after maxillary sinus floor augmentation: a radiographic and histological analysis

OBJECTIVES

To assess how anatomy and osteogenesis correlated with results of maxillary sinus floor augmentation (MSFA).

MATERIALS AND METHODS

Patients with partial edentulism and advanced atrophy of the posterior maxillae (≤ 4 mm residual bone height, RBH) underwent MSFA with sole deproteinized bovine bone matrix (DBBM) through a lateral approach. After a 6 to 9-month healing period, bone core biopsies were obtained from the sites of implant insertion for histological evaluation. The correlations between anatomical and histomorphometric variables were analyzed in a multiple regression model.

RESULTS

Forty-nine patients were recruited. One biopsy per patient was obtained from the augmented sinus. Thirty-seven bone core biopsies were intact and met the requirement for histomorphometry analysis. The mean (± standard deviation) percentages of vital bone (VB), remaining DBBM, and non-mineralized tissue were 18.25 ± 4.76%, 27.74 ± 6.68%, and 54.08 ± 6.07%, respectively. No statistically significant correlations were found between RBH and VB% (p = 0.44) or between sinus contour and VB% (p = 0.33). However, there was an inverse correlation between the sinus width (SW) and VB % (SW₁: R² = 0.13, p = 0.03; SW₂: R² = 0.15, p = 0.02).

CONCLUSIONS

After a healing period of 6-9 months, wider sinuses augmented with DBBM alone tended to have a lower proportion of new bone formation, while RBH and sinus contour did not appear to affect osteogenesis after MSFA.

CLINICAL RELEVANCE

This study emphasized the effect of anatomy on osteogenesis after MSFA. The result of the study may have an indication to the clinician that SW is a consideration when selecting the bone grafting material and deciding the healing period of MSFA.

Early bone formation in mini-lateral window sinus floor elevation with simultaneous implant placement: An in vivo experimental study

OBJECTIVE

To investigate the early bone formation in beagles with mini-lateral window sinus floor elevation and simultaneous implant placement.

MATERIAL AND METHODS

Six beagles were selected for the split-mouth design procedures. In each animal, one maxillary recess received a 5 mm-diameter mini-round lateral osteotomy (test group), and the contralateral maxillary recess received a large rectangular osteotomy (10 mm long and 8 mm wide), (control group). Simultaneous implant installation was executed on bilateral maxillary recesses. Tetracycline and calcein dyes were administered on the 14th, 13th days and the 4th, 3rd days prior to sacrifice, respectively. After 8 weeks of healing, the beagles were euthanized for fluorescent labeling and histomorphometric analyses.

RESULTS

In both groups, new bone formation initiated from the circumferential native bone of the maxillary recesses and extended toward the central sub-recess cavities. The maxillary recesses with the mini-window procedures exhibited superior mineral apposition rate, bone formation rate, and the percentage of new bone area to those of the group exposed to large osteotomy procedure (p < .05). While there was no significant difference in the value of bone-to-implant contact, the mini-window group displayed a tendency for an increase in this aspect (p > .05). Bone formation rate and new bone amount were not statistically correlated with bone-to-implant contact (p > .05).

CONCLUSION

The hypothesis that mini-lateral window sinus floor elevation with simultaneous implant placement would improve early new bone formation in augmented sinus compared with large lateral window procedure is accepted.

Involvement of the maxillary sinus ostium (MSO) in the edematous processes after sinus floor augmentation: a cone-beam computed tomographic study

Background

After sinus floor augmentation, a thickening of the sinus mucosa has been described. The aim of the present study was to evaluate the involvement of the maxillary sinus ostium in the edematous processes after a sinus floor augmentation procedure.

Methods

Seventy-two cone-beam computerized tomographies (CBSTs) were taken before sinus floor augmentation and after 1 week and 9 months from surgery and analyses. Sinus mucosa thickness and area, ostium diameter and patency, and extension of the post-surgical transient mucosal thickening in relation to the ostium were evaluated on the CBCTs for all three periods. The term “virtual” when referring to sinus mucosa thickness and area was introduced because of the edema and bleeding that both contributed to a transient thickening and additional elevation of the sinus mucosa.

Results

The mean virtual thickness of the sinus mucosa was 2.7 ± 4.0 mm, 7.7 ± 7.1 mm, 1.7 ± 2.0 mm before surgery, and after 1 week and 9 months. The virtual mucosa area was 37.2 ± 52.5 mm², 184.5 ± 153.8 mm², and 34.0 ± 50.7 mm². The ostium diameter at the three periods evaluated was 1.8 ± 0.5 mm, 1.1 ± 0.6 mm, 1.5 ± 0.8 mm, respectively. Three infundibula (4.2%) were found out of patency before surgery while this number increased to 14 (19.4%) after 1 week. Nine months after surgery, only one infundibulum (1.4%) was out of patency, however, without presenting signs of sinus pathologies. The extension of the mucosal edema on the palatal sinus was reduced after 9 months of healing.

Conclusions

One week after sinus floor augmentation, the maxillary sinus mucosa increased in dimensions and in several cases involved the ostium, reducing its diameter and producing a transient loss of patency. After 9 months of healing, the initial conditions were recovered.

New bone ingrowth into β-TCP/HA graft activated with argon plasma: a histomorphometric study on sinus lifting in rabbits

BACKGROUND

In a previous experimental study, new bone was found growing within granules of HA/β-TCP. In vitro and experimental studies have shown increased protein adsorption and cell adhesion graft material bioactivated with Argon plasma. The aims of the present experiment were to study new bone ingrowth into β-TCP/HA granules used as filler material for sinus lifting and the influence on the healing of the bioactivation of the graft with argon plasma.

METHODS

Sinus lifting was carried out in 20 rabbits using 60% HA and 40% β-TCP as filler material either bio-activated with argon plasma (plasma group) or left untreated (control group). The antrostomies were closed with collagen membranes. Biopsies representing the healing after 2 and 10 weeks were collected, and ground sections were prepared for histomorphometric analyses. Various regions of the elevated space were analyzed both around (outer bone; OB) and inside (interpenetrating bone network, IBN) the graft particles.

RESULTS

After 2 weeks of healing, 8.2% and 9.3% (n = 10; p = 0.635) of total new bone (OB + IBN) was found in the plasma and control groups, respectively. Small fractions of IBN were found, spreading from the periphery inward of the graft particles. After 10 weeks of healing, the total new bone was 34.0% in the plasma and 31.3% in Control groups (n = 9; p = 0.594). The respective fractions of IBN were 18.0% and 16.0%. New bone was penetrating from the peripheral regions inside the remnants of graft particles, where it was forming a network of bridges in continuity to the remnants of biomaterial through its porosities. The biomaterial decreased in proportion between 2 and 10 weeks from 52.1 to 28.3% in the plasma group, and from 52.5% to 31.9% in the control group.

CONCLUSION

The bio-activation with argon plasma on a synthetic graft composed of 60% HA and 40% β-TCP used as filler material for sinus lifting showed a tendency to improve bone formation; however, the difference with the control group was neither statistically significant nor clinically relevant.

Influence of the position of the antrostomy in sinus floor elevation on the healing of mini-implants: a randomized clinical trial

AIM

To evaluate histologically the healing of mini-implants installed after sinus floor elevation using a lateral approach and placing the antrostomy at different level from the sinus floor.

MATERIAL AND METHODS

Sinus floor elevation using a lateral approach was performed in 24 healthy volunteers. The antrostomy was randomly placed either close to the base of the sinus floor (group base) or at about 3-4 mm cranially to it (group standard). After 6 months of healing, mini-implants were installed within the grafted region, through the alveolar crest. Three months later, biopsies were collected.

RESULTS

Sixteen biopsies from 16 patients were available for histological analyses. The new bone reached fractions of 40.9 ± 11.9% and 48.5 ± 20.1% at the base and standard groups, respectively (p = 0.208). Xenograft particles were found in contact with the implant surface at percentages of 12.1 ± 11.0% in the base group, and 15.9 ± 23.7% in the standard group (p = 0.674).

CONCLUSIONS

Based on the present study, the choice of one or the other position of antrostomy did not influence significantly the outcome and, therefore, should be left to the preference of the surgeon.

Bone plate repositioned over the antrostomy after sinus floor elevation: an experimental study in sheep

The objective of this study was to compare the healing of the augmented sinus at which the antrostomy was covered with a membrane or the repositioned bone plate.Eight sheep underwent bilateral maxillary sinus floor augmentation. The control site was covered with a resorbable membrane, while at the experimental site the bone plate was repositioned, and both were secured with cyanoacrylate. Animals were euthanised after 4 months and histomorphometric analysis was performed.A large amount of the graft appeared to be partially interpenetrated by the newly formed bone. Statistical analysis demonstrated different percentages of the new bone and bone interpenetrated to the graft between test and control site in the close-to-window area respectively 22.1 ± 12.6 vs 7.5 ± 4.5 (P = 0.028) and 66.1 ± 14.7 vs 44.2 ± 15.1 (P = 0.046). Other areas showed no difference in the bone and graft amount. More bone was found at the edges of the antrostomy in the experimental site, without statistical significance. In the centre of the antrostomy, the replaced bony window appeared bonded to the newly formed bone. No remnants and no biological response to cyanoacrylate were observed.The repositioning of the bony window after sinus floor elevation in sheep led to a larger amount of newly formed bone in the close-to-window zone of the grafted area. The bony window appeared partially bonded to the new bone. Newly formed bone was found interpenetrating the graft granules.

Comparison of histomorphometry and microCT after sinus augmentation using xenografts of different particle sizes in rabbits

PURPOSE

The aim of the present experiment was to compare the data on new bone formation measured histologically and microtomographically in maxillary sinuses augmented with a xenograft with higher density and higher mineral content compared with the natural bone. The hypothesis was that histomorphometric and micro-computed tomography (microCT) analyses do not yield similar outcomes when a xenograft with higher density and mineral content compared with the natural bone is used.

METHODS

In 18 rabbits, the maxillary sinus was augmented bilaterally using deproteinized bovine bone mineral (DBBM) xenograft granules of either 0.125-1 mm or 1-2 mm of dimensions. The rabbits were euthanized after 2, 4, and 8 weeks of healing. Comparisons were performed between microCT and histological analyses.

RESULTS

After 2 weeks of healing, higher contents of bone were found at the histological compared with the microCT analyses in both sinuses, especially in the middle regions of the grafted sinus. Between 2 and 8 weeks of healing, new bone increased of about 21% at the histological analyses while, at the microCT, increased only about 4%. In the same period, the xenograft proportion decreased from 51.6 ± 4.9 to 45.3 ± 3.3% at the histological analyses while, at the microCT, the xenograft appeared to increase in percentages.

CONCLUSION

Histological and microCT analyses yielded different outcomes when a xenograft with higher density and higher mineral content compared with the natural bone was used.

Sinus Floor Elevation and Antrostomy Healing: A Histomorphometric Clinical Study in Humans

OBJECTIVES

To compare the histomorphometric outcomes of biopsies collected from the antrostomy and from the alveolar crest of the maxillary sinus after a sinus-lift procedure.

MATERIAL AND METHODS

In 12 volunteers, sinus floor elevation was performed using collagenated corticocancellous porcine bone. Nine months after the surgery, 2 biopsies, 1 from the alveolar crest and 1 from the antrostomy, were collected for histological analysis.

RESULTS

Biopsies from 11 patients were available for histological analyses (n = 11). At the alveolar crest sites, the percentage of mineralized bone was 40.1 ± 14.1%, of bone marrow was 40.1 ± 18.0%, and of the xenograft was 14.7 ± 15.2%. Small amounts of soft tissue were found. At the antrostomy sites, the percentages of mineralized bone, bone marrow, and xenograft were 26.0 ± 10.8%, 23.4 ± 17.0%, and 28.2 ± 15.7%, respectively. Soft tissue was represented by 19.7 ± 19.4%.

CONCLUSION

Higher amounts of mineralized bone and bone marrow were found in the alveolar crest compared with the antrostomy.

Management of Schneiderian Membrane Perforations during Sinus Augmentation Procedures: A Preliminary Comparison of Two Different Approaches

BACKGROUND

The aim of this study was to retrospectively analyze two different sealing techniques for sinus membrane perforations produced during sinus floor augmentation by a lateral approach.

METHODS

A total of 172 lateral-approach sinus floor augmentation surgeries were performed on 130 patients. Sixty-one membrane perforations (35%) were reported. Most of the perforations were caused by accidental membrane tearing and 16 (26%) were caused by deliberate incision for mucocele removal. In 31 perforation cases (51%), the Schneiderian membrane was sealed by suturing, while the remaining 30 cases (49%) were sealed using a low-resorption collagen membrane coverage.

RESULTS

Out of the 31 cases treated with a suture-sealing techniques, 26 (84%) were successful, presenting graft integration. Failure occurred in the other five (16%) cases. Out of the 30 perforations sealed with low-resorption collagen membranes, 28 (93%) presented successful graft integration, while two (7%) failed.

CONCLUSIONS

Both surgical techniques yielded therapeutic success.

Effect of staged crestal maxillary sinus augmentation: A case series

BACKGROUND

In sinus augmentation, when remaining bone height is ≤5 mm, a lateral window approach is often the preferred choice; nonetheless, patients prefer to have a less invasive approach such as crestal sinus augmentation (CSA). Prior case reports have described the use of various staged approaches of a CSA technique in cases of limited bone height. The aim of this report was to describe the results of a case series in which a two-stage CSA technique was used in patients with 4 to 6 mm of bone height.

METHODS

Nineteen subjects with 28 sinuses of initial vertical bone height of 4 to 6 mm were included in which a two-stage CSA technique was used in place of a lateral window approach. In the first surgery, 0.3 mL graft material was inserted into all sites. In the second surgery, 13 sites were filled with 0.2 mL graft material and remaining 15 sites were filled with 0.4 mL.

RESULTS

No damage was observed in the maxillary sinus floor membrane after first 0.2 mL filling; however, one case had Schneiderian membrane perforation after filling 0.4 mL. The average elevation height (EH) after first surgery was 5.81 ± 0.7 mm, 5.15 ± 0.91 mm before second surgery, 6.69 ± 0.89 mm with 0.2 mL filling (total 0.5 mL) and 8.11 ± 1.24 mm with 0.4 mL filling (total 0.7 mL). The thickness of maxillary sinus membrane before first surgery was 2.6 ± 2.59 mm; however, it has become 0.97 ± 1.59 mm before second surgery, with a decrease of 1.6 mm estimate.

CONCLUSION

This case series that assessed outcomes of staged crestal maxillary sinus augmentation was an effective approach to elevating 6 or 8 mm alveolar bone height without causing major membrane perforation. However, the two-stage approach was used in the limited residual bone height (4 to 6 mm) and required two separate surgical procedures.

Tomographic evaluation of the influence of the placement of a collagen membrane subjacent to the sinus mucosa during maxillary sinus floor augmentation: a randomized clinical trial

Aim

To study the influence of a collagen membrane placed subjacent to the sinus mucosa on the dimensional changes of augmented maxillary sinus floor.

Methods

Twenty patients were recruited in the study and randomly assigned to two groups. After the elevation of the maxillary sinus mucosa, a collagen membrane with standardized dimensions was placed at the test sites subjacent to the sinus mucosa and the elevated space was filled with a xenograft, both at test and control sites. A collagen membrane was then used to cover the antrostomy at both sites, and sutures were applied to close the wounds. Cone beam computed tomographies (CBCTs) were taken for all patients before surgery (T0), after 1 week from sinus floor augmentation (T1), and after 9 months of healing (T2). Dimensional changes over time of soft and hard tissues were evaluated on the CBCTs.

Results

After 1 week of healing, the sinus floor was elevated by 10.0 ± 2.8 mm and 10.6 ± 2.5 mm at the no-membrane and membrane groups, respectively. After 9 months of healing, a similar reduction of the height was observed in both groups, providing a total vertical augmentation of 8.6 ± 2.8 mm at the no-membrane sites and 9.1 ± 3.1 mm at the membrane sites. After 9 months of healing, the hard tissues subjacent to the sinus mucosa appeared to be partially corticalized in three patients in the no-membrane group and in six patients in the membrane group.

Conclusions

The use of collagen membranes subjacent to the sinus mucosa did not influence the dimensional variations of the augmented regions and the clinical outcomes after 9 months of healing also in absence of perforations.

Anatomical analyses for maxillary sinus floor augmentation with a lateral approach: A cone beam computed tomography study

BACKGROUND

Various anatomical references and structures should be analyzed prior approaching a surgery in the maxillary sinus. The objective of the present study was to evaluate the anatomical structures and references involved in sinus floor elevation with a lateral approach.

MATERIALS AND METHODS

Seventy-five patients planned for sinus floor elevation were included in the study. Eighty-eight maxillary sinuses were evaluated using cone beam computed tomographies (CBCTs). The nasal floor was used as main reference (X) and sinus mucosa width, bone crest height, palatal-nasal recess angle (PNR), sinus width at the level of the nasal floor, distance from the nasal floor to the base of the sinus (X-F), position of the posterior superior alveolar artery (PSAA height) and diameter (PSAA diameter), lateral bone wall width at 3mm (LW 3mm) and 9mm (LW 9mm) from the base of the sinus (F), patency of the ostium (OP), and presence and position of septa have been evaluated.

RESULTS

The mean dimensions and standard deviations were the following: mucosa thickness was 2.0±1.4mm, bone crest height 2.8±1.4mm, distance X-F 8.3±1.9mm, PNR angle 135.5±23.1, sinus width 12.6±4.2mm, X-F 8.3±1.9mm, PSAA height 14.4±2.9mm, PSAA diameter 1.1±0.4mm, LW 3mm 1.5±1.2, LW 9mm 1.3±0.6mm, OP 1.9±0.4mm. Septa were present in 19.3% of the sinuses evaluated and were located mostly in the molar region.

CONCLUSIONS

In conclusion, the analysis of the CBCT before sinus floor elevation allows the identification of anatomical structures and references that might be used for the planning of the surgical approach, aiming to improve the outcome of the treatment and to avoid possible complications.

Sinus floor elevation in sites with a perforated schneiderian membrane: What is the effect of placing a collagen membrane in a rabbit model?

OBJECTIVE

To investigate the healing following sinus grafting in sites with a perforated schneiderian membrane repaired using a collagen membrane, compared to control sites without membrane perforation.

MATERIALS & METHODS

Following elevation of the sinus membrane in 16 rabbits, each sinus was assigned to one of the following groups: (a) intentional schneiderian membrane perforation, followed by the placement of a collagen membrane and bone grafting (group SMP) and (b) bone grafting without a perforation of the schneiderian membrane and without a collagen membrane placement (control group). At 2 and 4 weeks (n = 8 for each time-point), microcomputed tomographic (micro-CT) and histomorphometric analyses were performed.

RESULTS

Overall new bone formation in group SMP was significantly delayed compared to the control group at 2 and 4 weeks (1.58 ± 1.25% vs. 9.23 ± 2.69% at 2 weeks, 10.43 ± 3.55 vs. 17.86 ± 4.11% at 4 weeks, p < 0.05). At 2 weeks, new bone formation for the areas close to lateral (1.19 ± 2.02%) and medial sinus bone walls (3.17 ± 1.98%) was markedly delayed in group SMP compared to the control group (13.08 ± 6.13% and 12.75 ± 5.63%, respectively, p < 0.05), but there was no statistical difference in those areas at 4 weeks (p > 0.05). The augmented volumes at 2 and 4 weeks were not statistically significantly different in both groups.

CONCLUSION

The perforation of the schneiderian membrane and the repair using a collagen membrane delayed new bone formation in the augmented sinuses. However, the extension of the collagen membrane on the sinus bone walls was also attributable to this delayed bone formation.

Immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing for failing teeth in the maxillary molar area: A randomized controlled trial clinical study with one-year follow-up

BACKGROUND

In previous studies, immediate implant placement in molar sites has been widely applied.

PURPOSE

To study the clinical effect and feasibility of immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing for failing teeth in the maxillary molar area.

MATERIAL AND METHODS

Patients who required implantation surgry to replace a failing tooth in the maxilla molar region were selected. Patients were randomized into two groups: immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing (test group) or delayed implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing (control group). The outcome criteria were the success rates of implants, Cone Beam Computer Tomography (CBCT) data and results of the subjective satisfaction survey performed with a visual analog scale (VAS).

RESULTS

All implants had good initial stability after implantation. The survival rate of implants was 100% at 1-year follow-up. At the time of permanent restoration, the differences in average horizontal shrinkage of alveolar bone (W1) on the buccal side between the test group (0.65 ± 0.12 mm) and the control group (1.23 ± 0.32 mm) were statistically significant (P < .0001); however, no statistically significant difference (P = .515) was observed on the palatal side (0.3 ± 0.10 mm vs 0.28 ± 0.08 mm). The difference in vertical resorption of alveolar bone (H1) on the buccal side between the test group (0.60 ± 0.18 mm) and the control group (1.53 ± 0.19 mm) was statistically significant (P < .0001), but no statistically significant difference (P = .190) in the reduction of palatal alveolar bone (0.24 ± 0.12 mm vs 0.29 ± 0.13 mm) was observed. After 1-year loading, no statistically significant difference (P > .05) in vertical or horizontal changes (W2, H2) were identified in the test group or control group. Patient satisfaction in both groups was similar (8.36 ± 1.01 vs 8.14 ± 1.35), and the difference between groups was not statistically significant (P = .638).

CONCLUSION

Immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing is feasible for the maxillary molar area, and the clinical effect is satisfactory.

Clinical outcome and factors determining new bone formation in lateral sinus membrane elevation with simultaneous implant placement without grafting material: A cross-sectional, 3-17 year follow-up study

BACKGROUND

Lateral sinus membrane elevation with simultaneous implant placement without grafting material (graft-less LSFE) is a widely investigated method for bone augmentation of the maxillary sinus floor. Long-term follow-up studies are rare.

PURPOSE

This study aimed to investigate the long-term effects of implants placed with graft-less LSFE.

MATERIALS AND METHODS

The study group was comprised of 111 patients previously treated with graft-less LSFE. The first follow-up visit, which occurred after a mean of 5 years after surgery, included a clinical examination, cone beam computerized tomography, and panorama or intraoral radiography. The second follow-up included panorama or intraoral radiography, and it was conducted after a mean of 8 years.

RESULTS

Overall, 218 implants were placed in 127 sinuses. Nine of the 218 implants failed resulting in an overall implant survival of 95.9%. The average bone gain at the follow-up was 4.0 ±2.0 mm.

CONCLUSION

The implant-supported rehabilitation achieved using graft-less LSFE was stable over time, and there was no or little impact on sinus health. Furthermore, it was concluded that the new bone formation and the amount of bone gain is proportional to the length of the implant protruding into the sinus cavity.

Early postoperative reactions following lateral sinus floor elevation using piezosurgery: A radiographic study

BACKGROUND AND PURPOSE

Early postoperative reactions occur following lateral sinus floor elevation (LSFE). This article radiographically describes, quantifies, and measures these early postoperative changes inside grafted maxillary sinus area.

MATERIALS AND METHODS

In 24 patients, 31 maxillary sinuses were performed using piezosurgery and grafted by bioceramic materials. Cone beam computed tomography was done preoperatively and then postoperatively, randomly, at either day 1 (n = 6), 2 (n = 11), 3 (n = 8), or 7 (n = 6) and at 6 months for all patients. Membrane thickening and subsequent swelling ratio, submucosal edema, and air bubbles inside grafted area were noted and measured. Inflammation was classified as mild, moderate, or severe.

RESULTS

Preoperative mean membrane thickness was 0.75 mm then following LSFE it significantly increased at days 1, 2, 3, and 7 and was respectively 2.36, 4.14, 6.05, and 6.63 mm. Mean swelling ratio significantly increased over time and was 11.37, 13.73, 16.34 and 35.78 at days 1, 2, 3, and 7, respectively. Submucosal edema height was noted in 24 cases. It had a mean value of 3.35 mm and increased significantly with time. Inflammation inside grafted area was mild in 7, moderate in 15, and severe in 9 of the cases. It significantly increased with time. Apical air bubble was present in 19 cases and had mean dimensions of 6.6 × 4.6 mm. No inflammatory signs were noted at 6 months.

CONCLUSIONS

Inflammatory reactions are always noted following LSFE and tend to increase with time reaching peak values at 7 days. All inflammatory changes significantly subsided at 6 months.

Sinus augmentation analysis of the gradient of graft consolidation: a split-mouth histomorphometric study

OBJECTIVE

The aim of this study was to histomorphometrically test the hypothesis that graft consolidation originates from the sinus floor.

MATERIALS AND METHODS

This prospective, randomized split-mouth study investigated patients undergoing bilateral maxillary lateral sinus floor augmentation using either freeze-dried bone allografts (FDBAs) or biphasic calcium phosphate (BCP) bone substitute. Apico-coronal core biopsies were harvested during implant placement 9 months after sinus floor augmentation, processed for histological observation, and measured histomorphometrically.

RESULTS

Biopsies were taken from 26 bilateral sites in 13 patients. The density of new bone (NB) decreased with increasing distance from the sinus floor. The percentage mean surface of NB ranged from 31 ± 9.5% at 2 mm from the sinus floor (G1) to 27.7 ± 11.2% at 4 mm (G2) for the FDBA specimens and from 30.0 ± 11.0% at G1 to 23.5 ± 9.9% at G2 for the BCP specimens. Evaluation of the residual graft particle (GP) area alone as a function of distance from the floor revealed a clear inverse gradient of 7.1 ± 6.6 to 9.1 ± 10.3 between G1 and G2 for the FDBA allografts, with the same tendency for the BCP alloplasts (21.9 ± 9.9 to 27.7 ± 6.6, respectively).

CONCLUSION

Our results support the concept that osteogenesis initiates in regions proximal to the bony walls of the maxillary sinus and may be enhanced by them.

CLINICAL RELEVANCE

The nature of the grafting material had a greater influence on the degree of NB formation in regions distant from the native walls where there is reduced inherent osteogenic potential.

Histological and micro-computed tomography evaluations of newly formed bone after maxillary sinus augmentation using a xenograft with similar density and mineral content of bone: An experimental study in rabbits

The objective of this study was to evaluate possible differences in the assessment of bone formation between histological and micro-computed tomography (CT) analyses in maxillary sinuses augmented with a xenograft with similar density and mineral content of bone. A collagen membrane was placed subjacent the elevated sinus mucosa at the test sites of 18 rabbits, and the elevated spaces were filled with xenograft. The antrostomy was covered with collagen membranes, bilaterally. Six rabbits per group were sacrificed after 2, 4, and 8 weeks of healing. Biopsies were retrieved and scanned in a high-resolution micro-CT at two different gray thresholds. Histological assessments were subsequently performed. At the histological analyses, bone increased over time, from 7.5 ± 2.4% to 27.0 ± 5.3%, between 2 and 8 weeks of healing. The highest content of bone was found close to the sinus bone walls, whereas the middle regions contained lower amounts. At the micro-CT analyses, discrepancies were found in bone content percentages compared with the histological analyses, especially after 2 weeks of healing and within the middle regions of the sinus, in which new bone was ~15-22% at the micro-CT analyses and only 1.6% at the histological evaluation. The outcomes of a micro-CT analysis performed in an early phase of healing may be altered when a resorbable bone substitute with similar density and mineral content of bone is applied.

Blood clot stability and bone formation following maxillary sinus membrane elevation and space maintenance by means of immediate implant placement in humans. A computed tomography study

OBJECTIVE

The present controlled clinical pilot study proposed to assess blood clot contraction and bone neo-formation following maxillary sinus lift (MSL) with immediate implant placement without using grafts using cone beam tomography exams.

MATERIALS AND METHODS

Ten implants were placed in ten patients with a residual bone crest height ≥4 and ≤ 7 mm, in maxillary premolars or 1st or 2nd molars regions, using MSL and immediate implant placement without grafts, by means of the lateral window approach. A resorbable membrane (Bio-Gide®, Geistlich, USA) was used to close the window. Computed tomography images were taken after 15 (T1) and 180 (T2) days to assess the rate of blood clot contraction and bone neo-formation. The images were analysed by OsirixMD software. The Shapiro Wilk test was used to verify the normality hypothesis and the data were submitted to Student's paired t-test.

RESULTS

The mean of bone clot height in mesial, apical and distal area referred to implant, presented 4.77 mm, 0.77 mm and 5.30 mm respectively. The mean measurements of new bone formation presented 2.95 mm, 0.44 mm and 3.45 mm. The height contraction (coagulum/new bone formation), between T1 and T2, presented 38%, 43% and 35% respectively, with a significant statistical value p < 0.05. The volume measurements at T1 presented a mean volume of 0.90 cm³ sd ± 0.60 cm³ and at T2 a mean volume of 0.75 cm³ sd ± 0.62 cm³, with a significant volume contraction between T1 and T2, p < 0.005. The mean blood clot contraction was 16.52% ± 8.60%.

CONCLUSION

The present study demonstrates consistent bone formation around all assessed implants, although with significant contraction of the blood clot. The need for longitudinal studies to establish a long-term prognosis in different modalities of prosthetic rehabilitation of those implants is strongly suggested.

Influence of the position of the antrostomy in sinus floor elevation assessed with cone-beam computed tomography: A randomized clinical trial

AIM

The aim of the present study was to evaluate dimensional variations of augmented sinus volumes after sinus floor elevation using a lateral approach placing the antrostomy close to the sinus floor or more cranially to it.

METHODS

Twenty-four healthy volunteers in need of sinus floor elevation were included in the study. The lateral approach was adopted placing the antrostomy randomly either close to the level of the sinus floor (group A) or approximately 3-4 mm cranially (group B). Cone-beam computed tomography (CBCT) was done before surgery (T0) and after 1 week (T1) and 9 months (T2), and analyses on dimensional variations were performed.

RESULTS

CBCT of 10 patients per group were analyzed. At T1, the sinus floor was found to be elevated by 9.8 ± 2.1 mm in group A and 10.9 ± 1.9 mm in group B. At T2, shrinkage of 2.0 ± 1.7 mm in group A and 1.4 ± 2.5 mm in group B was observed. The area was reduced approximately 18-24% between T1 and T2. The sinus mucosa width increased by 4.3-5 mm between T0 and T1, and regained the original dimensions at T2.

CONCLUSIONS

The more cranial the antrostomy, the greater the augmentation height after 9 months.

Sinus Membrane Elevation with Heterologous Cortical Lamina: A Randomized Study of a New Surgical Technique for Maxillary Sinus Floor Augmentation without Bone Graft

Background: The aim of this randomized controlled clinical trial was to compare the efficacy of two different techniques for maxillary sinus augmentation using a lateral window approach: Heterologous cortical lamina without any grafting material versus 100% collagenated granular collagen porcine bone. Methods: Twenty-three healthy patients with not relevant past medical history (14 women and 9 men, non-smokers, mean age 52 years, range 48–65 years) were included. In Group I, the sinus was filled with collagen porcine bone (Geno-os, OsteoBiol, Turin, Italy) and a collagen membrane (Evolution, OsteoBiol, Turin, Italy) was used to close the lateral window of the sinus. In Group II, the sinus was treated with heterologous cortical lamina only (Lamina, OsteoBiol, Turin, Italy). Results: There was a statistically significant difference in the surgical time required to complete the augmentation procedures: 18.3 ± 2.1 min for lamina treated sites versus 12.5 ± 3.1 min for porcine bone treated sites. In Group I, the mean volume of the graft was 3101 ± 321 mm³ in the immediate postoperative examination (5–7 days), while after a six-month healing period it was 2716.7 ± 432 mm³. Conclusion: This study demonstrates that the use of heterologous cortical lamina is a valid technique for the mechanical support of sinus membranes resulting in only bone tissue formation and not mixed with the graft. The graft material was biocompatible and not completely resorbed after six months, although the remains were integrated into the bone.

Endo-sinus bone formation after transalveolar sinus floor elevation without grafting with simultaneous implant placement: Histological and histomorphometric assessment in a dog model

AIM

To evaluate endo-sinus new bone formation and implant osseointegration after transalveolar sinus floor elevation (TSFE) and simultaneous implant placement without any grafting materials and to investigate the influence of implant surface modification on bone healing process under this circumstance.

MATERIALS AND METHODS

Transalveolar sinus floor elevation and simultaneous implant placement were conducted bilaterally on 12 Labrador dogs. No grafting materials were used during surgery. Implants with two different surfaces (SLA and SLActive) were placed in a split-mouth design. The animals were sacrificed 4, 8 and 24 weeks after surgery for histological and histomorphometric assessments. Bone-to-implant contact (BIC%), alveolar bone height (ABH) and the percentages of mineralized bone (MB%) in the area of interest were analysed. The probing depth (PD) and bleeding on probing (BOP) were also assessed to describe peri-implant health conditions.

RESULTS

Sprouts of new bone in direct contact with implant surface were seen in the elevated area at every time point. Newly formed woven bone under sinus membrane was visible. SLActive implants exhibited favourable results compared with SLA implants regarding ABH at 4 weeks and BIC% at 4 and 8 weeks. Sites with BOP positive could be observed in both groups at any time point. No newly formed bone can be found on the implant apex with either SLA or SLActive surfaces at any time point.

CONCLUSIONS

Spontaneous new bone formation from the parent bone walls could be observed after TFE without any grafting materials. No clear evidence of bone formation from the Schneiderian membrane could be found. Even though there were trends for quicker bone response of SLActive implants, this study failed to show the absolute advantage of SLActive in achieving endo-sinus bone formation.

Lateral Sinus Floor Elevation Performed with Trapezoidal and Modified Triangular Flap Designs: A Randomized Pilot Study of Post-Operative Pain Using Thermal Infrared Imaging

Purpose: Post-operative pain and swelling are frequently observed after sinus lift procedures. The aim of the present study was the clinical evaluation of swelling and pain of two different sinus flap lift techniques using a visual analogue scale (VAS), verbal rating scale (VRS), and infrared thermal imaging (i.e., thermography). Materials Methods: A randomized controlled trial was conducted with 15 patients (30 sinuses in total) randomly allocated into two groups. For the sinuses of Group I a trapezoidal flap was used, while for Group II a modified triangular flap without anterior release was utilized. Postoperative pain was scored by means of a 100-mm VAS ranging from 0 (no pain) to 100 (worst pain imaginable), and was recorded at 2, 4, 6 and 14 days after surgery. Swelling was recorded by a verbal rating scale (VRS) and was classified into four categories: a score of 1 referred the absence of swelling, patients with intra-oral swelling in the surgical zone scored 2, any extra-oral swelling in the surgical zone scored 3, and intense swelling exhibited by extra-oral swelling extending beyond the surgical zone scored 4. The facial temperature was recorded before and after sinus augmentation, and at 2, 4, 6, and 14 days post-surgery to check the course of healing. Results: In Group I pain intensity was recorded at 2 days after surgery with a mean score of 38.67 ± 6.4 mm. Swelling was greater at 2 and 4 days, and was absent at day 6. The facial temperature difference before and after the procedure was 4.737 &deg;C ± 0.37. In Group II the pain score were lower than in Group I (p < 0.05). The score for swelling was 2 on the first and second days, and was reduced on day 4. After the second day the difference in temperature was significantly reduced as compared to the day of surgery (0.77 &deg;C); at 2 and 4 days no difference was registered. Conclusions: The results of this clinical study show the significant effectiveness of the modified triangular flap in the sinus lift procedure for reducing pain and swelling.

Reposition of the bone plate over the antrostomy in maxillary sinus augmentation: A histomorphometric study in rabbits

OBJECTIVE

To test if repositioning the bony plate secured with a cyanoacrylate over the antrostomy in maxillary sinus augmentation was superior to covering the antrostomy with a collagen membrane in terms of the bone augmentation area and the bone density.

MATERIAL AND METHODS

After the exposure of the nasal bone in eighteen rabbits, a rectangular access window was prepared with a sonic instrument, and the bony plate was removed. A bilateral sinus mucosa elevation was performed, and the space was filled with a resorbable xenograft. On the test side, the bone plate was repositioned over the antrostomy and fixed with a cyanoacrylate. On the control side, a collagen membrane was placed over the opening. Per group, six animals were sacrificed after 2, 4, and 8 weeks of healing, respectively. Histological ground sections were prepared.

RESULTS

The augmented area after elevation decreased between 2 and 8 weeks from 9.4 ± 1.8 to 4.8 ± 2.8 mm² at the test and from 9.5 ± 2.6 and 5.1 ± 1.6 mm² at the control sites. Small amounts of new bone were seen after 2 weeks in both groups (~1.6%-2.5%) forming from the bony sinus walls. New bone density increased over time in both groups reaching ~ 10%-11% and ~ 23%-25% after 4 and 8 weeks, respectively. No statistically significant differences were found. Small residual defects were present both at the test sites in the margin of the bone plate, and at the control sites in the center of the antrostomy.

CONCLUSIONS

The bone healing in the elevated sinus space was similar irrespective of the coverage of the antrostomy. After 8 weeks, the bone plate repositioned on the antrostomy was incorporated while at the control sites the healing was still incomplete. Residual defects were still present in both groups.

Sinus floor elevation procedures to enable implant placement and integration: techniques, biological aspects and clinical outcomes

Implant treatment in an atrophied edentulous posterior maxilla constitutes a challenge for the therapeutic team. The authors of the present study acknowledge that modern micro-rough surface implants in lengths of about 8-10 mm or longer and of different brands are similarly successful. Consequently, the authors propose that the use of different sinus floor elevation techniques should be considered when < 8 mm of bone is available below the maxillary sinus. The type of sinus floor elevation technique selected is mainly based on residual vertical bone height, marginal bone width, local intrasinus anatomy and the number of teeth to be replaced, although other factors (such as surgical training and surgical experience) may have an impact. It is proposed that a transcrestal sinus floor elevation approach can be considered as a first-choice method for single tooth gaps in situations with sufficient width for implant placement and a residual bone height of 5-8 mm, while lateral sinus floor elevation, with or without grafting materials, is indicated when < 5 mm of bone is available and when several teeth are to be replaced. With regard to time of implant placement, a one-stage procedure is preferred provided that high primary stability can be ensured.

New bone formation after transcrestal sinus floor elevation was influenced by sinus cavity dimensions: A prospective histologic and histomorphometric study

OBJECTIVE

The aim of this multicenter prospective study was to analyze clinically and histologically the influence of sinus cavity dimensions on new bone formation after transcrestal sinus floor elevation (tSFE).

MATERIAL AND METHODS

Patients needing maxillary sinus augmentation (residual crest height <5 mm) were treated with tSFE using xenogeneic granules. Six months later, bone-core biopsies were retrieved for histological analysis in implant insertion sites. Bucco-palatal sinus width (SW) and contact between graft and bone walls (WGC) were evaluated on cone beam computed tomography, and correlations between histomorphometric and anatomical parameters were quantified by means of forward multiple linear regression analysis.

RESULTS

Fifty consecutive patients were enrolled and underwent tSFE procedures, and forty-four were included in the final analysis. Mean percentage of newly formed bone (NFB) at 6 months was 21.2 ± 16.9%. Multivariate analysis showed a strong negative correlation between SW and NFB (R²  = .793) and a strong positive correlation between WGC and NFB (R²  = .781). Furthermore, when SW was stratified into three groups (<12 mm, 12 to 15 mm, and >15 mm), NFB percentages (36%, 13% and 3%, respectively) resulted significantly different.

CONCLUSIONS

This study represented the first confirmation based on histomorphometric data that NFB after tSFE was strongly influenced by sinus width and occurred consistently only in narrow sinus cavities (SW <12 mm, measured between buccal and palatal walls at 10-mm level, comprising the residual alveolar crest).

A prospective randomized controlled trial of the two-window technique without membrane versus the solo-window technique with membrane over the osteotomy window for maxillary sinus augmentation

BACKGROUND

Maturation of the grafted volume after lateral sinus elevation is crucial for the long-term survival of dental implants.

PURPOSE

To compare endo-sinus histomorphometric bone formation between the solo- and two-window maxillary sinus augmentation techniques with or without membrane coverage for the rehabilitation of multiple missing posterior teeth.

MATERIALS AND METHODS

Patients with severely atrophic posterior maxillae were randomized to receive lateral sinus floor elevation via the solo-window technique with membrane coverage (Control Group) or the two-window technique without coverage (Test Group). Six months after surgery, bone core specimens harvested from the lateral aspect were histomorphometrically analyzed.

RESULTS

Ten patients in each group underwent 21 maxillary sinus augmentations. Histomorphometric analysis revealed mean newly formed bone values of 26.08 ± 16.23% and 27.14 ± 18.11%, mean connective tissue values of 59.34 ± 12.42% and 50.03 ± 17.13%, and mean residual graft material values of 14.6 ± 14.56% and 22.78 ± 10.83% in the Test and Control Groups, respectively, with no significant differences.

CONCLUSIONS

The two-window technique obtained comparative maturation of the grafted volume even without membrane coverage, and is a viable alternative for the rehabilitation of severely atrophic posterior maxillae with multiple missing posterior teeth.

Maxillary Sinus Augmentation Using a Titanium Mesh: A Randomized Clinical Trial

BACKGROUND

Various attempts have been implemented using different materials and techniques to augment the maxillary sinus floor for prospect dental implant positioning.

AIM

This contemplate was conducted to assess the osteogenic capability of the maxillary sinus in a two-step sinus membrane elevation using titanium mesh to keep the formed space to place dental implants in atrophic ridges.

MATERIALS AND METHODS

Titanium micromesh was customized and positioned into the sinus on one side to preserve the elevated membrane in position. On the other side xenograft was applied. Instant and 6-months postoperative cone beam computed tomography (CBCT) was done to assess the gained bone height and density. Bone core biopsies were obtained during implant placement for histological and histomorphometric evaluation.

RESULTS

The average bone height values increased in both groups. Meanwhile the average bone density value was higher at the graft group than the titanium mesh group. Histological and histomorphometric evaluation presented the average bone volume of the newly formed bone in the graft group which is superior to that of the titanium mesh group.

CONCLUSION

The use of the titanium micromesh as a space-maintaining device after Schneiderian membrane elevation is a trustworthy technique to elevate the floor of the sinus without grafting.

Influence of a collagen membrane positioned subjacent the sinus mucosa following the elevation of the maxillary sinus. A histomorphometric study in rabbits

OBJECTIVE

To evaluate the healing after elevation of the sinus mucosa when a collagen membrane was placed between the sinus mucosa and a xenograft used as filler.

MATERIALS AND METHODS

Eighteen rabbits were used. Sinus mucosa elevation was performed bilaterally, and a collagen membrane was applied subjacent to the sinus mucosa only at a randomly selected test site. At both sites, a collagenated corticocancellous porcine bone was placed within the elevated space and the access window was covered with a collagen membrane. The animals were sacrificed after 2, 4, and 8 weeks of healing, six animals for group. Ground sections were prepared.

RESULTS

At the histomorphometric evaluation, the elevated area after 2 and 8 weeks was 11.8 and 8.8 mm² at the test, and 10.0 and 5.3 mm² at the control sites, respectively. The available area was obtained subtracting the remaining area occupied by the membrane from the elevated area and, after 8 weeks, was 6.7 ± 0.9 mm² . After 8 weeks of healing, the mineralized new bone within the elevated space was 18.2 ± 5.5% at the test and 26.7 ± 7.7% at the control sites. Within the available space at the test site, the percentage was 27.3 ± 7.0% after 8 weeks of healing. At 2 and 8 weeks of healing, within the elevated space, the xenograft proportion was 30.9 ± 4.4% and 6.9 ± 2.8% at the test, and 35.2 ± 7.3% and 9.6 ± 4.9% at the control sites, respectively.

CONCLUSIONS

The placement of a collagen membrane subjacent the sinus mucosa did not reveal any major morphometric difference. The collagen membrane was not completely resorbed after 8 weeks.