A systematic review of the success of sinus floor elevation and survival of implants inserted in combination with sinus floor elevation

Interventions for replacing missing teeth: augmentation procedures of the maxillary sinus

BACKGROUND

Insufficient bone volume is a common problem encountered in the rehabilitation of the edentulous posterior maxillae with implant-supported prostheses. Bone volume is limited by the presence of the maxillary sinus together with loss of alveolar bone height. Sinus lift procedures increase bone volume by augmenting the sinus cavity with autogenous bone or commercially available biomaterials, or both. This is an update of a Cochrane review first published in 2010.

OBJECTIVES

To assess the beneficial or harmful effects of bone augmentation compared to no augmentation when undertaking a sinus lift procedure. Secondly, to compare the benefits and harms of different maxillary sinus lift techniques for dental implant rehabilitation.

SEARCH METHODS

We searched the Cochrane Oral Health Group's Trials Register (to 17 January 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 12), MEDLINE via OVID (1946 to 17 January 2014) and EMBASE via OVID (1980 to 17 January 2014). There were no language or date restrictions on the searches of the electronic databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of different techniques and materials for augmenting the maxillary sinus for rehabilitation with dental implants that report the outcome of implant success or failure at least to four months after initial loading.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the risk of bias of the trials, and data extraction were conducted independently and in duplicate. Authors were contacted for any missing information. Results were expressed using fixed-effect models as there were either less than four studies or we used Peto odds ratios (ORs) for dichotomous data when there were zero cells in either the treatment or control or both arms and the number of trials was small. The statistical unit of the analysis was the patient.

MAIN RESULTS

Eighteen RCTs out of 64 potentially eligible study reports met the inclusion criteria. They compared undertaking a sinus lift with not doing so, and the use of different sinus lift techniques. There were 650 patients providing data for the outcomes evaluated. Five studies were assessed as low risk of bias, 11 were assessed as high risk of bias, and in two the risk was unclear. Sinus lift versus no sinus lift Four trials of moderate quality (three trials at low and one at high risk of bias) with 102 participants evaluated short implants (5 to 8.5 mm long) as an alternative to sinus lift in bone with residual height between 4 and 9 mm. One year after loading there was insufficient evidence to claim differences between the two procedures for prosthesis failure (OR (Peto) 0.37, 95% confidence interval (CI) 0.05 to 2.68; three trials) or implant failure (OR (Peto) 0.44, 95% CI 0.10 to 1.99; four trials). There was however an increase in complications at treated sites when undertaking the sinus lift (OR (Peto) 4.77, 95% CI 1.79 to 12.71, P value = 0.002; four trials). Different sinus lift techniques Fourteen trials with 548 participants compared different sinus lift techniques. Only three comparisons included more than one trial (two trials for each). These were bone graft versus no bone graft, autogenous bone versus bone substitute, bone graft with or without platelet-rich plasma (PRP). There was insufficient evidence to claim a benefit for any of these techniques for the primary outcomes of prosthesis and implant failure. For the other reported outcomes, in a single study at high risk of bias, only bone gain was greater for the bone graft site than the site without a graft six months after augmentation, however this was not significant at 18 or 30 months.The other comparisons with single studies were rotary versus piezosurgery to open a lateral sinus window, two different bone substitutes, use or not of a membrane to seal the lateral window, one- versus two-stage lateral sinus lift, two-stage granular bone versus one-stage autogenous bone blocks, and crestal versus lateral sinus lift; two trials compared three different crestal sinus lifting techniques: rotatory versus hand malleting (patients preferred rotatory instruments over hand malleting) and hand versus electric malleting. There was no evidence of a benefit for any sinus lift procedure compared to any other for the primary outcomes prosthesis or implant failure.

AUTHORS' CONCLUSIONS

There is moderate quality evidence which is insufficient to determine whether sinus lift procedures in bone with residual height between 4 and 9 mm are more or less successful than placing short implants (5 to 8.5 mm) in reducing prosthesis or implant failure up to one year after loading. However, there are more complications at sites treated with sinus lift procedures. Many trials compared different sinus lift procedures and none of these indicated that one procedure reduced prosthetic or implant failures when compared to the other. Based on low quality evidence, patients may prefer rotary instruments over hand malleting for crestal sinus lift.

Implant success remains high despite grafting voids in the maxillary sinus

OBJECTIVES

Given that the nature and presence of voids present within grafted sinuses following maxillary sinus elevation procedures were not known, nor was the contribution of these factors to implant success, the purpose of this study was to investigate these parameters and their relationship to implant success.

MATERIALS AND METHODS

This study evaluated data from 25 subjects who had a lateral window maxillary sinus augmentation procedure. Cone-beam computed tomography (CBCT) was performed at baseline and 4 months after surgery. CBCT images were used to evaluate grafted sites prior to implant placement. Using CBCT images, three examiners independently measured bone-grafted areas (BG), void areas (V), and percentage of void areas (V%) from six different sections within grafted sites. The six sections were defined as a cross-sectional (CS) midpoint, CS mesial point, CS distal point, horizontal section (HS) low point, HS midpoint, and HS high point. Implant success was also determined.

RESULTS

The calculated V% (V/BG) for the CS midpoint, CS mesial point, CS distal point, HS low point, HS midpoint, and HS high point were 5.30 ± 6.67%, 5.79 ± 8.51%, 6.67 ± 7.12%, 2.07 ± 2.56%, 5.30 ± 6.62%, and 4.92 ± 5.17% respectively. Implant success after 6 months of follow-up approximated 100%.

CONCLUSIONS

Although voids within grafts varied in terms of distribution and size, the V% within the HS low point were significantly smaller compared to those within the CS midpoint and CS distal point, which had the most intra-subject V%. Thus, more attention should be given to the distal aspect of the sinus when compacting graft materials in the lateral wall sinus augmentation procedure. Implant success was not influenced by the existence of voids as implant success remained high.

Sequential healing of the elevated sinus floor after applying autologous bone grafting: an experimental study in minipigs

AIM

To describe the sequential healing after elevation of the maxillary sinus mucosa applying the lateral access technique with the use of autogenous bone grafting without membrane to occlude the osteotomy access.

MATERIAL AND METHODS

Immediately after the elevation of the maxillary sinus Schneiderian membrane, applying the lateral access technique in 10 minipigs, autologous bone was harvested from the lateral aspect of the mandibular molar region and ground into particles with a bone mill. The space under the Schneiderian membrane was filled with this graft. No membranes were placed onto the access osteotomy. The healing was evaluated after 15, 30, 90 and 180 days. Paraffin sections were prepared and analyzed histologically.

RESULTS

After 15 days of healing, the elevated area was mainly filled with provisional matrix, newly formed bone and some remnants of bone chips, and appeared reduced in volume compared with that at the time of surgery. After 30 days of healing, further shrinkage of the height of the elevated space was found, with similar percentages of the different tissue components. After 90 and 180 days, the area underneath the Schneiderian membrane appeared reduced in volume and condensed toward the base of the sinus. The bone tissues appeared to be more mature, both for the mineralized and the non-mineralized portions, while connective tissue occupied 20% of the space, most likely related to the lack of the use of a membrane occluding the access at the time of surgery.

CONCLUSIONS

Suboptimal healing outcomes with respect to augmentation of the space under the sinus floor membrane were documented when autologous bone chips were used as a filler and no membrane was applied to cover the access.

A pilot-study of a minimally invasive technique to elevate the sinus floor membrane and place graft for augmentation using high hydraulic pressure: 18-month follow-up of 20 cases

OBJECTIVE

To evaluate medical efficacy and safety of crestal, minimally invasive sinus floor augmentation (MISFA) using an innovative method based on high hydraulic pressure.

STUDY DESIGN

Twenty MISFA using the novel Jeder-System were performed in 18 patients at 2 study sites in Vienna, Austria. The Jeder-System consists of the Jeder-drill, the Jeder-pump, and a connecting tube-set. The pump generates high hydraulic pressure (1.5 bar) pushing back the sinus membrane from the drill at the first perforation. The pump also monitors the whole procedure by constantly measuring pressure and volume.

RESULTS

Five percent membrane perforation rate (1/20) only detected in the postoperative computed tomography scan and without implication for implant placement. Height gain of 9.2 ± 1.7 mm achieved (from 4.6 ± 1.4 mm to 13.8 ± 2.3 mm). Average patient satisfaction was 9.82 on scale from 1 to 10 (10 = very satisfied). Mean duration of sick leave was 0.19 days. 18-month survival rate was 95% (1/20 implant lost).

CONCLUSIONS

Within the limits of a prospective open cohort study with 20 cases, our data demonstrate the safety and medical efficacy of the novel method.

Osseointegration of short titan implants: A pilot study in pigs

Reduced vertical bone level in the implantation area is often considered one of the limiting factors before implant insertion. Inserting implants of reduced length might be useful in order to avoid vertical bone augmentation prior to implantation. To the present day, no official guidelines exist as to the optimal length for these implants. It is nevertheless well known that the stability of an implant depends primarily on its osseointegration, which could otherwise be influenced by modifying implant surface texture. The aim of our study was to evaluate osseointegration in correlation with implant length and surface texture. Three different variations of titan implants (n=5) were compared: two types, each with an acid-etched and ceramic blasted surface, were inserted in the upper jaw of adult female minipigs at different lengths (tioLogic ST Shorty, 5mm length; tioLogic ST, 9mm length) and were compared to a control group (tioLogic ST, 9mm length, ceramic blasted surface). Eight weeks after unloaded healing, bone tissue specimens containing the implants were processed, stained with Masson-Goldner-trichrome and analyzed histologically. Regardless of implant length and surface texture, new bone formation with no signs of inflammation could be detected in the area of the threads. Implants with a modified surface showed no statistically significant difference in bone-implant-contact (BIC) (tioLogic ST Shorty, 56.5%; tioLogic(©)ST; 77.2%), but a statistically significant difference could be found, when the 9mm implants were compared to the control group (BIC 48.9%). Surface modification could positively influence osseointegration as well as contribute to overcoming the adverse effects of length reduction.

A Prospective Noninterventional Study to Evaluate Survival and Success of Reduced Diameter Implants Made From Titanium-Zirconium Alloy

Narrow diameter implants may be at increased risk of overload due to occlusal forces; therefore, implants with higher fatigue strength may be beneficial. The aim of this observational study was to evaluate survival and success of narrow diameter (Ø 3.3 mm) TiZr alloy (Roxolid, Institut Straumann AG, Basel, Switzerland) implants for 2 years in daily dental practice. This was a prospective, non-interventional, multicenter study; no specific patient inclusion or exclusion criteria were applied. Each patient received at least one TiZr implant; the treatment plan, including implant loading and final restoration, was at the investigator's discretion. The primary outcome was implant survival and success after 1 year. Secondary outcomes included 2-year survival and success and marginal bone level change. A total of 603 implants were placed in 357 patients. Cumulative survival and success rates were 97.8% and 97.6%, respectively, after 1 year and 97.6% and 97.4%, respectively, after 2 years. Bone levels remained stable in the majority of patients, and soft tissue remained stable up to 2 years. Within the limitations of a non-interventional study design, TiZr implants showed excellent survival and success with minimal bone loss up to 2 years in daily dental practice. The results compare favorably with those of small-diameter implants in controlled clinical trials.

Tenting effect of the elevated sinus membrane over an implant with adjunctive use of a hydroxyapatite-powdered collagen membrane in rabbits

PURPOSE

The aim of this study was to determine the de novo bone formation beneath the Schneiderian membrane supported by an implant and with the adjunctive use of a hydroxyapatite-powdered collagen (HAC) membrane without bone grafting in rabbit sinuses.

MATERIAL AND METHODS

After sinus-floor elevation procedure, an experimentally devised mini-implant (4 mm in length and 3 mm in diameter) was placed in eight rabbits. For the experimental group, an HAC membrane was placed onto the elevated sinus mucosa prior to implant placement. The animals were allowed a healing period of either 4 or 8 weeks. Microcomputed tomography and histologic analyses were performed.

RESULTS

All implants placed at the thin lateral bony wall were histologically osseointegrated. The topography of the newly formed bone appeared to slope gently from the medial side down to the lateral side. The volume of new bone was significantly greater in the experimental group than in the control group at 4 weeks (P < 0.05), but not at 8 weeks. However, none of the samples in the two groups was entirely covered to the apex by bone tissue.

CONCLUSIONS

It can be concluded that using the HAC membrane in combination with placement of an implant resulted in substantial bone formation around the implant, which might have been influenced by the proximity of the axial bony wall.

Schneiderian membrane detachment using transcrestal hydrodynamic ultrasonic cavitational sinus lift: a human cadaver head study and histologic analysis

PURPOSE

Recent studies have suggested the osteogenic layer of the periosteum at the base of the sinus membrane to play a key role in bone regeneration after sinus lift procedures. Thus, atraumatic detachment of the sinus membrane with an intact periosteum seems mandatory. The present histologic study of fresh human cadaver heads investigated the detachment behavior and histologic integrity of the detached periosteum after application of the transcrestal hydrodynamic ultrasonic cavitational sinus lift (tHUCSL-INTRALIFT).

MATERIALS AND METHODS

A total of 15 sinuses in 8 fresh human cadaver heads were treated using tHUCSL-INTRALIFT. After surgery, they were checked macroscopically for damage to the sinus membrane and then processed for histologic inspection under light microscopy. A total of 150 histologic specimens, randomly selected from the core surgical sites, were investigated using hematoxylin-eosin (HE), Azan, and trichrome staining.

RESULTS

None of the 150 inspected specimens showed any perforation or dissection of the periosteum from the subepithelial connective tissue and respiratory epithelium and were fully detached from the bony antrum floor. The connecting Sharpey fibers revealed to be cleanly separated from the sinus floor in all specimens.

CONCLUSIONS

The results of the present study suggest tHUCSL-INTRALIFT should be used to perform predictable and safe detachment of the periosteum from the bony sinus floor as a prerequisite for undisturbed and successful physiologic subantral bone regeneration.

Are there specific indications for the different alveolar bone augmentation procedures for implant placement? A systematic review

Bone resorption following tooth loss often interferes with dental implant placement in a desired position, and requires additional bone augmentation procedures. Many techniques have been described to augment and reconstruct alveolar ridge width and height. The aim of this study was to systemically review whether there is evidence to provide indications for the various bone augmentation procedures based on defect dimension and type. An electronic search of the Medline database and Cochrane library, complemented by a manual search, was performed. Inclusion criteria for partial edentulism were: clinical trials on bone augmentation procedures in preparation or at the time of implant placement, reporting preoperative and postoperative dimensions of the ridge. For edentulous patients, studies were included when providing the data on ridge and defect description, or the amount of augmentation achieved. The search yielded 53 publications for partially edentulous patients and 15 publications for edentulous patients. The literature provides evidence that dehiscence and fenestrations can be treated successfully with guided bone regeneration (GBR) at the time of implant placement (mean implant survival rate (MISR) 92.2%, mean complication rate (MCR) 4.99%). In partially edentulous ridges, when a horizontal defect is present, procedures such as staged GBR (MISR 100%, MCR 11.9%), bone block grafts (MISR 98.4%, MCR 6.3%), and ridge expansion/splitting (MISR 97.4%, MCR 6.8%) have proved to be effective. Vertical defects can be treated with simultaneous and staged GBR (MISR 98.9%, MCR 13.1% and MISR 100%, MCR 6.95%, respectively), bone block grafts (MISR 96.3%, MCR 8.1%), and distraction osteogenesis (MISR 98.2%, MCR 22.4%). In edentulous patients, there is evidence that bone block grafts can be used (MISR 87.75%), and that Le Fort I osteotomies can be applied (MISR 87.9%), but associated with a high complication rate. The objective of extracting specific indications for each procedure could not be fully achieved due to the heterogeneity of the studies available. Further studies on bone augmentation procedures should report precise preoperative and postoperative measurements to enable a more exact analysis of the augmentation procedure, as well as to provide the clinician with the rationale for choosing the most indicated surgical approach.

Comparison of tissue-engineered bone from different stem cell sources for maxillary sinus floor augmentation: a study in a canine model

PURPOSE

To compare the potential of tissue-engineered bone derived from different stem cell sources for canine maxillary sinus augmentation.

MATERIALS AND METHODS

Bilateral maxillary sinus floor augmentations were performed in 6 beagles and were randomly repaired with 3 graft types: Bio-Oss granules alone (n = 4; group A), a complex of osteoblasts derived from bone marrow mesenchymal stem cells (BMMSCs) and Bio-Oss (n = 4; group B), and a complex of osteoblasts derived from periodontal ligament stem cells (PDLSCs) and Bio-Oss (n = 4; group C). After 12 weeks, fluorescent labeling, maxillofacial computed tomography, scanning electron microscopy, and histologic and histomorphometric analyses were used to evaluate new bone deposition, mineralization, and remodeling in the augmented area.

RESULTS

The osteogenic capacity was greater in groups B and C than in group A. The level tended to be higher in group C than in group B; however, the difference was not statistically significant.

CONCLUSIONS

Seeding of PDLSCs or BMMSCs onto Bio-Oss can promote bone formation and mineralization and maintain the maximum volume of the augmented maxillary sinus. These tissue-engineered bone complexes might be a good option for augmentation of the maxillary sinus in edentulous patients.

Assessment of the autogenous bone graft for sinus elevation

OBJECTIVES

The posterior maxillary region often provides a limited bone volume for dental implants. Maxillary sinus elevation via inserting a bone graft through a window opened in the lateral sinus wall has become the most common surgical procedure for increasing the alveolar bone height in place of dental implants in the posterior maxillary region. The purpose of this article is to assess the change of bone volume and the clinical effects of dental implant placement in sites with maxillary sinus floor elevation and autogenous bone graft through the lateral window approach.

MATERIALS AND METHODS

In this article, the analysis data were collected from 64 dental implants that were placed in 24 patients with 29 lacks of the bone volume posterior maxillary region from June 2004 to April 2011, at the Department of Oral and Maxillofacial Surgery, Inha University Hospital. Panoramic views were taken before the surgery, after the surgery, 6 months after the surgery, and at the time of the final follow-up. The influence of the factors on the grafted bone material resorption rate was evaluated according to the patient characteristics (age and gender), graft material, implant installation stage, implant size, implant placement region, local infection, surgical complication, and residual alveolar bone height.

RESULTS

The bone graft resorption rate of male patients at the final follow-up was significantly higher than the rate of female patients. The single autogenous bone-grafted site was significantly more resorbed than the autogenous bone combined with the Bio-Oss grafted site. The implant installation stage and residual alveolar height showed a significant correlation with the resorption rate of maxillary sinus bone graft material. The success rate and survival rate of the implant were 92.2% and 100%, respectively.

CONCLUSION

Maxillary sinus elevation procedure with autogenous bone graft or autogenous bone in combination with Bio-Oss is a predictable treatment method for implant rehabilitation.

Osteotome sinus floor elevation with and without grafting: an animal study in Labrador dogs

AIM

To evaluate implant stability and histological outcomes after osteotome sinus floor elevation (OSFE) procedure, and to compare new bone formation and implant osseointegration with and without grafting.

MATERIAL AND METHODS

OSFE with simultaneous implant placement was conducted bilaterally on 6 Labrador dogs. Twenty-four implants were placed. The right side sinus (Group 1) was grafted with biphasic calcium phosphate (BCP), whereas the left side (Group 2) was left without any grafting materials. The animals were euthanized 8 and 24 weeks after surgery for histological and histomorphometric assessment. Bone-to-implant contact (BIC%), alveolar bone height (ABH), bone density (BD) and grafting material density (GMD) were measured. The implant stability (ISQ) was assessed using resonance frequency analysis (RFA) at implant placement and 1, 2, 4, 8, 12, 24 weeks after surgery.

RESULTS

Endo-sinus new bone with direct contact to implant surface were observed in two groups at both time points. ABH showed no difference between groups at both time points. BIC% and BD in Group 2 (40.05%, 35.90%) was higher than those in Group 1 (23.30%,25.59%) at 24 weeks. Significant shrinkage of grafting material was seen in Group 1. The GMD in Group 1 at 8 weeks was 24.35%, while it dropped to 19.90% at 24 weeks. The changing pattern of ISQ for both groups were similar.

CONCLUSIONS

Spontaneous new bone formation and better bone-to-implant contact were found for OSFE without grafting. The grafting material application during OSFE procedure showed no advantages in histological results.

Systematic review of the survival rate and the incidence of biological, technical, and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of 5 years

OBJECTIVE

To assess the 5-year survival of implant-supported single crowns (SCs) and to describe the incidence of biological, technical, and aesthetic complications. The focused question was: What is the survival rate of implants supporting single crowns and implant-supported crowns with a mean follow-up of 5 years and to which extent do biological, technical, and aesthetic complications occur?

METHODS

A Medline search (2006-2011) was performed for clinical studies focusing on implant-supported SCs with a mean follow-up of at least 5 years. The search was complemented by an additional hand search and the inclusion of 24 studies from a previous systematic review (Jung et al. 2008a). Survival and complication rates were analyzed using random-effects Poisson's regression models to obtain summary estimates of 5- and 10-year proportions.

RESULTS

Forty-six studies derived from an initial search count of 1083 titles and the complementary publications from the previous systematic review (Jung et al. 2008a) were selected and the data were extracted. Based on the meta-analysis, survival of implants supporting SCs at 5 years amounted to 97.2% (95% CI: 96.3-97.9%), and at 10 years amounted to 95.2% (95% CI: 91.8-97.2%). The survival of implant-supported SCs was 96.3% (95% CI: 94.2-97.6%) after 5 years and 89.4% (95% CI: 82.8-93.6%) after 10 years. For biological complications, a 5-year cumulative soft tissue complication rate of 7.1% (95% CI: 4.4-11.3%) and a cumulative complication rate for implants with bone loss >2 mm of 5.2% (95% CI: 3.1-8.6%) were calculated. Technical complications reached a cumulative incidence of 8.8% (95% CI: 5.1-15.0%) for screw-loosening, 4.1% (95% CI: 2.2-7.5%) for loss of retention, and 3.5% (95% CI: 2.4-5.2%) for fracture of the veneering material after 5 years. The cumulative 5-year aesthetic complication rate amounted to 7.1% (95% CI: 3.6-13.6%).

CONCLUSIONS

The outcomes of the meta-analysis demonstrated high implant survival rates for both the single tooth implants and the respective single crowns after 5 and 10 years. However, technical, biological, and aesthetic complications were frequent.

Maxillary sinus lateral wall thickness and morphologic patterns in the atrophic posterior maxilla

BACKGROUND

The aim of the present study is to examine the sinus lateral wall thickness (LWT) of atrophic posterior maxilla (<10 mm) of patients with complete and partial edentulism and determine the influence of residual ridge height (RH), sex, and age on maxillary LWT.

METHODS

Four hundred fourteen measures were taken from 140 consecutive patients that met the inclusion criteria. On the selected sagittal section, a built-in digital caliper recorded in millimeters the RH and LWT (a perpendicular line at 3, 5, 7, 10, 13, and 15 mm from the lowest point of the sinus floor). Edentulous spans were further classified as complete edentulous atrophic maxilla (CEM) and partial edentulous atrophic maxilla (PEM). The mixed linear model was used to test the effects of sex, type of edentulism, edentulous span, and RH on the measurement of the LWT of the sinus.

RESULTS

Mean LWT for PEM was 1.71 ± 0.12 mm, and for CEM, 1.57 ± 0.07 mm (P = 0.01). The mixed model yielded significant effect of edentulous span (P = 0.048) and interactions among type of edentulism and edentulous span (P <0.001) and edentulous span by RH (P <0.01). Age and RH were positively associated with LWT; however, they did not interact with RH, sex, or type of edentulism. RH has been shown to correlate with edentulous span (P <0.001) and type of edentulism (P = 0.01). The longer the edentulous span, the thinner the LWT. Similarly, RH was larger for PEM (6.85 ± 0.34 mm) than CEM (5.69 ± 0.26 mm).

CONCLUSIONS

The maxillary sinus lateral wall tends to increase in thickness from the second premolar to the second molar and from 5 mm up to 15 mm. In addition, RH, presence of teeth adjacent to the edentulous atrophic ridge, and age were shown to influence maxillary sinus LWT.

Residual ridge dimensions at edentulous maxillary first molar sites and periodontal bone loss among two ethnic cohorts seeking tooth replacement

OBJECTIVES

To study residual ridge dimensions at edentulous first molar sites in relation to periodontal bone loss among cohorts of partially edentulous Asian Indian and Hong Kong Chinese subjects seeking tooth replacement.

MATERIALS AND METHODS

A total of 628 edentulous maxillary first molar sites were analyzed on Cone Beam Computed Tomography scans of 225 Asian Indian (I) and 232 Hong Kong Chinese (C) partially edentulous adults seeking tooth replacement. Age, ethnicity, gender, total tooth loss, the presence or absence of adjacent teeth, categories of periodontal status defined according to radiographic alveolar bone loss (P0: periodontal health, P1: incipient to moderate disease, P2: severe periodontal disease) and sinus membrane abnormalities were noted. Alveolar ridge height (RH), widths at 1 and 3 mm from crest (RW1; RW3), and relative position of the bone crest (RR) were measured.

RESULTS

Prevalence of P2 status was most frequent in both cohorts(C: 50.4% I: 49.2%). P2 had lowest ridge heights; 13.1% C P2 and 14%I P2 had RH < 2 mm. Sites with both RH <8 mm and RW1 < 6 mm occurred at 59%C P2 and 68%I P2. Sinus membrane abnormalities were most frequent in P2. Periodontal status and sinus membrane abnormality increased the odds of RH <5 mm and RH <8 mm more than 2-fold; additionally, gender and ethnicity significantly impacted RH <8 mm. Gender and adjacent tooth status significantly affected RW1.

CONCLUSION

Incident advanced periodontal disease was common among Asian Indian and Hong Kong Chinese subjects seeking tooth replacement and associated with lower available bone heights. Ethnicity, gender, sinus membrane thickening affected available bone height in the subsinus region, while the presence of adjacent teeth- and age-affected residual ridge width.

Prevalence of Sinus Augmentation Associated With Maxillary Posterior Implants

Pneumatization of the maxillary sinus limits the quantity of alveolar bone available for implant placement and may result in a lack of primary stability and difficulty in achieving osseointegration. The purpose of this study was to retrospectively analyze a group of patients who had implants placed in the posterior maxilla, calculate the prevalence of sinus augmentation, and identify factors related to sinus augmentation. With institutional review board approval, dental records from a population of patients who had implants placed in the maxillary posterior region between January 2000 and December 2004 were used to create a database. Independent variables were classified as continuous (age of the patient at stage 1 implant surgery [S1], time between extraction and S1, time between extraction and sinus augmentation, and time between sinus augmentation and S1) and categorical (gender, implant failure, American Society of Anesthesiologists system classification, smoking, osteoporosis, residual crestal bone height, implant position, implant proximity, prostheses type, and implant diameter and length). The dependent variable was the incidence of a sinus augmentation procedure. Simple logistic regression was used to assess the influence of each factor on the presence of sinus augmentation (P &lt; .05). The final database included 502 maxillary posterior implants with an overall survival rate of 93.2% over a mean follow-up period of 35.7 months. Of 502 implants, 272 (54.2%) were associated with a sinus augmentation procedure. Among variables, residual crestal bone height (P &lt; .001), implant position (P &lt; .001), implant proximity (P &lt; .001), prosthesis type (P &lt; .001), implant failure (P &lt; .01), and implant diameter (P &lt; .01), were statistically associated with sinus augmentation. Within the limitations of this retrospective study, the results suggest that more than half (54.2%) of the maxillary posterior implants were involved with a sinus augmentation procedure. The prevalence of sinus augmentation increased with decreased residual crestal bone height, more posterior implant locations, and complete or partial edentulism. Sinus augmentation was significantly associated with implant failure and wide implants.

Evaluation of the posterior superior alveolar artery and the maxillary sinus with CBCT

Assessment of the maxillary sinus anatomy before sinus augmentation is important for avoiding surgical complications, because of the close anatomical relationship between the posterior maxillary teeth and the maxillary sinus. The posterior superior alveolar artery (PSAA) is the branch of the maxillary artery that supplies the lateral sinus wall and overlying membrane. We evaluated the location of the PSAA and its relationship to the alveolar ridge and maxillary sinus using cone beam computed tomography (CBCT). The study group consisted of 135 CBCT scans (270 sinuses) obtained from the archive of the dentomaxillofacial radiology department at Yeditepe University Faculty of Dentistry, Istanbul, Turkey. The distance between the lower border of the artery and the alveolar crest, bone height from the sinus floor to the ridge crest, distance from the artery to the medial sinus wall, and the diameter and location of the artery were determined. The occurrence of septa and pathology were recorded from CBCT scans. The PSAA was observed in 89.3% of sinuses, and 71.1% of arteries were intraosseous with diameters mostly < 1 mm (68.9%). The prevalence of sinus septa was 55.2%, and that of sinus pathology was 57.4%. The mean age was 43.07 ± 17.55 years. There was a statistically significant difference between the location of the artery and gender (p < 0.05). The prevalence of sinus membrane thickening was 57.4%. Detailed knowledge about the location of the PSAA and sinus morphology may be obtained with CBCT before maxillary sinus surgery.

A histomorphometric and micro-computed tomography study of bone regeneration in the maxillary sinus comparing biphasic calcium phosphate and deproteinized cancellous bovine bone in a human split-mouth model

OBJECTIVE

The gain of mineralized bone was compared between deproteinized bovine bone allograft (DBA) and biphasic calcium phosphate (BCP) for dental implant placement.

STUDY DESIGN

Five patients with atrophic maxillae underwent bilateral sinus elevation with DBA (Bio-Oss) and BCP (Straumann BoneCeramic). After 3 to 8 months, 32 Camlog implants were placed, and biopsies were retrieved. Bone and graft volume, degree of bone mineralization, and graft degradation gradient were determined using micro-computed tomography, and bone formation and resorption parameters were measured using histomorphometry. Implant functioning and peri-implant mucosa were evaluated up to 4 years.

RESULTS

Patients were prosthetically successfully restored. All but one of the implants survived, and peri-implant mucosa showed healthy appearance and stability. Bone volume, graft volume, degree of bone mineralization, and osteoclast and osteocyte numbers were similar, but BCP-grafted biopsies had relatively more osteoid than DBA-grafted biopsies.

CONCLUSIONS

The BCP and DBA materials showed similar osteoconductive patterns and mineralized bone, although signs of more active bone formation and remodeling were observed in BCP- than in DBA-grafted biopsies.

Is furcation involvement in maxillary molars a predictor for subsequent bone augmentation prior to implant placement? A pilot study

AIM

The aim of this pilot study was to analyze the interfurcal bone height in relation to the possible need for subsequent sinus floor elevation in patients with advanced periodontitis and furcation involvement of first and/or second maxillary molars.

MATERIAL AND METHODS

Seventeen dentate patients, who received cone beam computed tomography (CBCT) for detailed preoperative diagnosis and planning of surgical interventions at periodontally involved maxillary molars (17 first and 15 second molars), were consecutively recruited for the study. The minimal bone height in the interfurcal region was measured from CBCT and related to furcation involvement, residual bone above the root tips, and the clinical probing pocket depth (PPD).

RESULTS

The minimal interfurcal bone height measured 4.1 ± 2.6 mm on average with 75% of maxillary molars having ≤ 6 mm and almost 60% having only ≤ 4 mm bone height left below the sinus floor. A higher risk for reduced interfurcal bone height of ≤ 4 mm was given when residual PPD of ≥ 6 mm was remaining at two or more tooth sites (OR 0.10; 0.11).

CONCLUSIONS

The majority of periodontally involved maxillary molars had a substantially reduced interfurcal bone height, particularly with at least two sites with residual PPD ≥ 6 mm. This was a predictor for a subsequent need for sinus floor elevation when tooth replacement with a dental implant is desired.

Long-term survival of dental implants placed in the grafted maxillary sinus: systematic review and meta-analysis of treatment modalities

BACKGROUND

A prevalent modality to increase the amount of available bone prior to implantation is grafting of the maxillary sinus. Multiple factors such as the surgical technique, moment of implant placement as well as grafting materials and membranes are known to affect implant survival. However, the role of different factor combinations and associated reciprocal effects remain unclear. Conventional statistical methods do not consider inconsistency of study designs and do not take covariables into account. Hence, a systematic research and meta-analysis was conducted to investigate the influence of various treatment modalities on implant survival in the grafted maxillary sinus.

MATERIALS AND METHODS

A meta-analysis was conducted according to the PRISMA guidelines. Articles published from 1980 through January 2013 were electronically and manually searched in MEDLINE (Ovid), the Cochrane Register of Controlled Trials, the Database of Abstracts of Effects, and the Cochrane Database of Systematic Reviews. Clinical reports on single intervention sinus augmentation with root-form implants, a minimum of 10 patients and 6 months of loading were eligible for inclusion if implant survival was stated or calculable. Results were calculated by non-parametric univariate Kaplan-Meier analysis and Bayesian multivariate interval-censored Cox regression.

RESULTS

A total of 122 publications on 16268 endosseous implants placed in grafted maxillary sinus were included. The treatment parameters surgical approach, grafting material and implant type showed no selective preference. However, application of membranes showed a significantly reduced hazard-ratio, independent of other co-factors.

CONCLUSIONS

The use of membranes is the most significant factor to achieve long-term implant survival in sinus augmentation procedures. More data exceeding 3 years follow-up are needed to address prospective confounding and improve clinical evidence.

Volumetric dimensional changes of autogenous bone and the mixture of hydroxyapatite and autogenous bone graft in humans maxillary sinus augmentation. A multislice tomographic study

PURPOSE

This multislice tomographic study evaluated the dimensional changes after maxillary sinus augmentation using autogenous bone or a mixture of hydroxyapatite and autogenous bone.

MATERIALS AND METHODS

Ten selected patients, requiring a bilateral maxillary sinus augmentation, were divided, in a split mouth, design as follows: control group (CG n = 10 sinus grafted with autogenous bone) and test group (TG, n = 10 sinus grafted with a mixture of hydroxyapatite and autogenous bone at 80 : 20 w/w). Follow a healing period of 15 and 180 days, computed tomography (CT) measurements were taken by two blinded and calibrated examiners to verify the volumetric dimensional changes of the both groups.

RESULTS

The interobserver agreement obtained ranged from good to excellent for both groups. Both groups presented significant dimensional changes after 180 days period healing (P < 0.05). The volumetric reduction in test group was lower (25.87%) when compared with the CG (42.30%) (P < 0.05).

CONCLUSION

The both graft materials improved the bone volumetric ability to anchorage a dental implant. Moreover, the mixture of HA and autogenous bone graft showed lower degree of resorption and higher dimensional stability when compared with autogenous bone graft alone, at least at 180 days of healing. The CT exam protocol should be used as an important tool to measure bone grafts volumetric alterations.

Effect of leukocyte- and platelet-rich fibrin (L-PRF) on bone regeneration: a study in rabbits

BACKGROUND

The positive effect of leukocyte- and platelet-rich fibrin (L-PRF) on osteogenesis has been widely described in vitro. However, clinical and preclinical studies are very little and controversial in demonstrating a significant beneficial effect of L-PRF in bone regeneration.

PURPOSE

The goal of the present study was to compare the potential effect of L-PRF in a standardized model.

MATERIALS AND METHODS

A total of 72 hemispheres were implanted on the calvaria of 18 rabbits and filled with three different space fillers: L-PRF, bovine hydroxyapatite (BHA), BHA + L-PRF, and an empty hemisphere was used as control. Six rabbits were sacrificed at three distinct time points: 1 week, 5 weeks, and 12 weeks. Histological and histomorphometrical analyses were carried out.

RESULTS

At the early phase of bone regeneration (1 week), from a descriptive analysis, a higher proportion of connective tissue colonized the regeneration chamber in the two groups containing BHA particles. Nevertheless, no statistical differences were found within the four groups in terms of bone quantity and quality at each timepoint (p = .3623).

CONCLUSIONS

According to the present study, L-PRF does not seem to provide any additional effect on the kinetics, quality, and quantity of bone in the present model of guided bone regeneration.

Intraoperative complications during sinus floor elevation using two different ultrasonic approaches: a two-center, randomized, controlled clinical trial

PURPOSE

The aim of this study was to assess the prevalence of intraoperative complications during maxillary sinus elevation with lateral approach using a piezoelectric device with two different surgical techniques.

MATERIALS AND METHODS

Antrostomies were randomly performed by outlining a window (group A, 36 patients) or by eroding the cortical wall with a grinding insert until the membrane was visible under a thin layer of bone, before outlining the window (group B, 36 patients). Occurrence of membrane perforation, laceration of vascular branches, and surgical time was recorded.

RESULTS

Seventy-two patients underwent sinus floor elevation: four perforations (11.1%) were observed in group A (two occurred during elevation with hand instruments) and zero perforations in group B (p < .05). No evidence of vascular lacerations was registered in both groups. A clinically insignificant but statistically shorter surgical time was recorded in group A (9.2 ± 3.7 minutes) than in group B (13.3 ± 2.4 minutes; p < .05).

CONCLUSIONS

Within the limits of the present study, it may be concluded that ultrasonic erosion of the lateral wall of the sinus is a more predictable technique than piezoelectric outlining of a bone window in preventing from accidental perforations of Schneiderian membrane during sinus augmentation procedures.

The use of bone block allografts in sinus augmentation, followed by delayed implant placement: A case series

PURPOSE

This article reports the clinical outcomes observed in a large number of patients receiving block bone allograft used for sinus augmentation and delayed implant placement.

PATIENTS AND METHODS

In total, 28 patients (13 males) with a mean age of 49.8 ± 10.1 years (range: 33-67 years) were included in this case series. All selected patients suffered from severe alveolar ridge atrophy in the posterior maxilla and required bone augmentation procedures, followed by implant placement after 6 months. All patients were followed for 18 months after the grafting, with scheduled monthly visits and/or more frequent visits if required. The survival rates for both the bone blocks and placed implants were then evaluated.

RESULTS

A total of 42 blocks and 90 implants were placed. Only one bone graft and 5 implants failed; the survival rate was 97.2% and 95.5% for the bone grafts and implants, respectively. The graft failed due to the onset of post-surgical infectious sinusitis, while in some patients' implants showed absence of osteointegration at the end of the healing phase. Of note, all failed implants were observed in heavy smokers; in all other patients, blocks and implants were successful.

CONCLUSIONS

This preliminary case series suggests that the grafting of bone allograft followed by delayed implant placement may be a promising strategy for sinus augmentation. More extended and larger follow-up studies are needed to confirm this preliminary data.

A comparative study of the incidence of Schneiderian membrane perforations during maxillary sinus augmentation with a sonic oscillating handpiece versus a conventional turbine handpiece

BACKGROUND

Sonic instruments may reduce perforation rates of the schneiderian membrane during lateral window sinus augmentation procedures. This study compares the incidence of membrane perforations using a sonic handpiece with an oscillating diamond insert versus a turbine handpiece with a conventional rotary diamond stone during lateral window sinus augmentation procedures.

MATERIALS AND METHODS

A retrospective chart analysis identified all lateral window sinus augmentation procedures done during a defined period. Among these procedures, those performed with a sonic handpiece and an oscillating diamond insert (experimental) and those performed with a conventional turbine and rotary diamond stone (conventional) were selected for this study. Reported occurrences of sinus membrane perforations during preparation of the osteotomy and elevation of the sinus membrane, as well as postoperative complications, were recorded and compared between treatment groups.

RESULTS

Ninety-three consecutive patients were identified for a total of 130 sinus augmentation procedures (51 conventional, 79 experimental). Schneiderian membrane perforations were noted during preparation of the lateral window osteotomy in 27.5% of the sinuses in the conventional group and 12.7% of sinuses in the experimental group. During membrane elevation, perforations were noted in 43.1% of the sinuses in the conventional group and 25.3% of sinuses in the experimental group. Both differences in perforation rates were statistically significant (p < .05). There was no statistically significant difference in postoperative complications.

CONCLUSIONS

In this study, the use of a sonic instrument to prepare the lateral window osteotomy during sinus elevation procedures resulted in a reduced perforation rate of the Schneiderian membrane compared with the conventional turbine instrument.

A 5-year clinical and computerized tomographic implant follow-up in sinus-lifted maxillae and native bone

OBJECTIVES

The present study analysed apical and marginal bone remodelling around dental implants placed in both maxillary (sinus elevated with particulated autogenous osseous graft) and corresponding native bone areas, with a follow-up of 5 years. The clinical survival of implants was also observed.

MATERIALS AND METHODS

In this retrospective chart review, 27 patients were enrolled, with 55 dental implants inserted from 2000 to 2006, 26 of which were followed (one implant per patient); if required, patients were treated via sinus lift with autogenous bone and particulate technique. The internal controls were implants positioned in native areas beneath the sinus. Radiologic survey was assessed via computerized tomographic analysis measuring apical bone level (ABL) and marginal bone level (MBL), at 1- (T1 ), 3- (T2 ) and 5 years (T3 ), around implants (buccal, b; palatal, p; mesial, m; and distal sides, d). Clinical probing depth (CPD) and clinical attachment level (CAL) for all the four peri-implant aspects were measured. Cumulative survival rate (CSR) and survival rate (SR) of implants were calculated. Significances for paired and unpaired comparisons were searched for.

RESULTS

A significant degree of apical resorption was recorded between T1 and T3 for the mesial particulate group; again, a significant difference was discovered between the native and particulate procedures for mABL. A further feature was discovered for the particulate procedure, for which ABLs resulted negative at least for three of the aspects. Regarding MBL measurements, similar behaviours were revealed using time-comparison analysis for the two procedures at the buccal aspect. Comparisons among diameters, irrespective of the procedure, showed that resorption times for the bMBL were shorter as the diameter of the implant became wider. The implant CSR was 92% in native areas (two failures/25 implants) and 93.3% in sinuses lifted with particulate bone (two failures/30 implants).

CONCLUSIONS

The results suggest that a protrusion of the implant apices into augmented sinus lift occurred, whereas the bone remodelling of the coronal areas was not influenced by the events in the maxillary sinus. A diameter ranging from 4 to 5 mm might better guarantee a conservation of marginal peri-implant bone level compared with implants with smaller diameters.

Loss of pulp vitality after maxillary sinus augmentation: a surgical and endodontic approach

BACKGROUND

Maxillary sinus augmentation is a routine procedure performed in implant dentistry in cases with sinus pneumatization. This study presents a series of clinical cases in which tooth devitalization occurred in conjunction with sinus augmentation.

METHODS

In the three cases presented, a sinus-lift procedure was performed that resulted in devitalization of the adjacent teeth. Patients were referred to an endodontist for evaluation and treatment. Vitality of the teeth was determined by the use of a cold test, electric pulp test, and cavity test. The pulp was considered to be necrotic if the tests were negative.

RESULTS

In this case series, loss of pulp vitality of two maxillary left second premolars and one maxillary left first molar occurs after sinus-augmentation procedures. The devitalized teeth were free of caries. In one case, two amalgam restorations were present.

CONCLUSION

Pulp necrosis may occur in conjunction with a sinus-lift procedure in cases when an adjacent root is in close proximity to the sinus floor and the sinus membrane is elevated over the root apex.

Volumetric changes after sinus augmentation using blocks of autogenous iliac bone or freeze-dried allogeneic bone. A non-randomized study

OBJECTIVES

To compare volumetric bone changes after sinus augmentation for implant positioning using blocks of autogenous iliac bone or freeze-dried allogeneic bone (FDBA) from the hip. Variables were compared between the two sources and for each surgical procedure at set times (pre- and post-augmentation procedure).

PATIENTS AND METHODS

A non-randomized retrospective chart review of 7 patients who had autogenous and 7 allogeneic block grafts was carried out (1 procedure per patient). Analysis of Computer Tomographic (CT) data of maxillary sinuses, acquired with high-speed, double-detector CT scanner, was performed using dentascan software. The change between the preoperative (T0) and postoperative volume was measured at 4-6 months (T2) and 1.5 year after transplantation (T3). Annual- and overall-rates of bone change were calculated for the two sources.

RESULTS

All patients were partially edentulous with a residual maxillary floor thickness in the planned implant insertion sites of 2.7 (0.5) mm and 2.8 (0.5) mm for allogeneic and autogenous procedures respectively. From identical intraoperative volume of grafts (2.25 cc at T1), volumetric changes were recorded at T2 and T3. The final volume of the grafts was 1.44 cc for allogeneic group and 1.78 cc for the autogenous group. Significant volumetric changes over time of transplanted grafts for both sources (23% for autograft and 18% for allograft) were found at T2. At 1.5-years post-operatively comparisons of volumes and rates of bone loss between sources were not statistically significant. No failure was recorded for either bone grafts or dental implants.

CONCLUSIONS

Short-term sinus grafting procedure for dental implant placement performed with FDBA showed an outcome close to that reported for autogenous bone. Volumetric changes were comparable between the sources. These data suggest that performing maxillary sinus augmentation with dry-preserved bone allogeneic materials in block form could be considered even when the residual floor thickness is less than 3 mm.

Recombinant human bone morphogenetic protein-2 stimulates the osteogenic potential of the Schneiderian membrane: a histometric analysis in rabbits

This study evaluated the osteoinductive effect of the recombinant human bone morphogenetic protein-2 (rhBMP-2)-coated biphasic calcium phosphate (BCP) carrier system on the grafted sinus area, including surrounding tissues and the Schneiderian membrane. A total of 18 male rabbits were used in this study; two for in vitro and 16 for in vivo experiments. Schneiderian membranes taken from two animals were cultured with or without rhBMP-2, and quantitative reverse transcriptase-polymerase chain reaction analysis was performed. Both maxillary sinuses in each of the 16 animals were used to compare the in vivo effects of rhBMP-2-coated BCP (experimental group) and BCP alone (control group). In each animal, rhBMP-2-coated BCP was grafted into one of the maxillary sinuses, and the same amount of BCP alone was grafted into the contralateral site in random order. Radiologic and histometric analyses were performed at 2 and 8 weeks after surgery. After 2 days of culturing with or without rhBMP-2, a significant increase in the expression of early osteoblasts (RUNX2, type I collagen, alkaline phosphatase, and osteopontin) could be observed. Different histologic healing patterns were observed in experimental and control sites: newly formed bone lining the reflected sinus membrane without bone formation was observed at the central areas of experimental sites (window=0.06%; center=0%; membrane=20.86% of new bone), whereas evenly distributed new bone formation was observed at the control sites (window=7.27%; center=7.41%; membrane=15.58% of new bone).The augmented volume was well maintained at both the experimental and control sites during the experimental period, but at 2 weeks, the augmented volume was greater at the experimental sites than at the control sites (232.62 and 195.29 mm(3), respectively; p<0.001). These results suggest that good space maintenance in sinus augmentation is achieved with BCP, while the osteoinductive potential of the sinus membrane is activated at the early stage of healing with rhBMP-2.

Radiographic outcomes of transcrestal sinus floor elevation performed with a minimally invasive technique in smoker and non-smoker patients

OBJECTIVES

To evaluate the association between smoking status and the outcomes of transcrestal sinus floor elevation (tSFE) performed with a minimally invasive technique (Smart Lift).

METHODS

Forty-five implants were placed in 25 non-smoker (NS) and 20 smoker (S) patients in conjunction with the tSFE procedure. In all cases, an additional graft, chosen among different hydroxyapatite-based or ß-tricalcium phosphate-based biomaterials, was pushed into the sinus by gradual increments. Immediately after surgery, residual bone height, implant penetration into the sinus, extent of sinus lift (SL) and the height of the graft apical to the implant apex (aGH) were assessed on periapical radiographs. At 6 months after surgery, SL and aGH were reassessed.

RESULTS

(i) The Smart Lift procedure resulted in substantial 6-month SL and aGH in both treatment groups; (ii) smoking status did not significantly affect the 6-month radiographic outcomes; (iii) a similarly low incidence of intra- and postoperative complications was observed in NS and S patients.

CONCLUSIONS

Smoking has a limited impact on the outcomes of tSFE performed with the Smart Lift technique.

Peri-implant bone length changes and survival rates of implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height

Purpose

The aim of this study was to measure the peri-implant bone length surrounding implants that penetrate the sinus membrane at the posterior maxilla and to evaluate the survival rate of these implants.

Methods

Treatment records and orthopantomographs of 39 patients were reviewed and analyzed. The patients had partial edentulism at the posterior maxilla and limited vertical bone height below the maxillary sinus. Implants were inserted into the posterior maxilla, penetrating the sinus membrane. Four months after implant insertion, provisional resin restorations were temporarily cemented to the abutments and used for one month. Then, a final impression was taken at the abutment level, and final cement-retained restorations were delivered with mutually protected occlusion. The complications from the implant surgery were examined, the number of failed implants was counted, and the survival rate was calculated. The peri-implant bone lengths were measured using radiographs. The changes in initial and final peri-implant bone lengths were statistically analyzed.

Results

Nasal bleeding occurred after implant surgery in three patients. No other complications were found. There were no failures of the investigated implants, resulting in a survival rate of 100%. Significantly more bone gain around the implants (estimated difference=-0.6 mm, P=0.025) occurred when the initial residual bone height was less than 5 mm compared to the >5 mm groups. No significant change in peri-implant bone length was detected when the initial residual bone height was 5 mm or larger.

Conclusions

This study suggests that implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height may be safe and functional.

Cone-beam computed tomographic analysis of sinus membrane thickness, ostium patency, and residual ridge heights in the posterior maxilla: implications for sinus floor elevation

OBJECTIVE

To determine, using cone-beam computed tomography (CBCT), the residual ridge height (RRH), sinus floor membrane thickness (MT), and ostium patency (OP) in patients being evaluated for implant placement in the posterior maxilla.

MATERIALS AND METHODS

CBCT scans of 128 patients (199 sinuses) with ≥1 missing teeth in the posterior maxilla were examined. RRH and MT corresponding to each edentulous site were measured. MT >2 mm was considered pathological and categorized by degree of thickening (2-5, 5-10 mm, and >10 mm). Mucosal appearance was classified as "normal", "flat thickening", or "polypoid thickening", and OP was classified as "patent" or "obstructed". Descriptive and bivariate statistical analyses were performed.

RESULTS

MT >2 mm was observed in 60.6% patients and 53.6% sinuses. Flat and polypoid mucosal thickening had a prevalence of 38.1% and 15.5%, respectively. RRH ≤4 mm was observed in 46.9% and 48.9% of edentulous first and second molar sites, respectively. Ostium obstruction was observed in 13.1% sinuses and was associated with MT of 2-5 mm (6.7%), 5-10 mm (24%), and >10 mm (35.3%, P < 0.001). Polypoid mucosal lesions were more frequently associated with ostium obstruction than flat thickenings (26.7% vs. 17.6%, P < 0.001).

CONCLUSION

Thickened sinus membranes (>2 mm) and reduced residual ridge heights (≤4 mm) were highly prevalent in this sample of patients with missing posterior maxillary teeth. Membrane thickening >5 mm, especially of a polypoid type, is associated with an increased risk for ostium obstruction. In the presence of these findings, an ENT referral may be beneficial prior to implant-related sinus floor elevation.

Healing properties of implants inserted concomitantly with anorganic bovine bone. A histomorphometric human study

BACKGROUND

The present prospective, randomized, double-blind study evaluated the bone-forming process around implants inserted simultaneously with anorganic bovine bone (ABB) in sinus grafting.

METHODS

A total of 18 threaded mini-implants with Osseotite (O) and Nanotite (N) surfaces were placed in seven patients (nine sites). After 12 months, the implants were retrieved and processed for histological analysis. A total of 18 cutting and grinding sections were investigated with bright-field light microscopy, circularly polarized light microscopy (CPLM), confocal scanning laser microscope (CSLM), and scanning electron microscope (SEM) with energy dispersive spectrometer (EDS).

RESULTS

The bone-to-implant contact rate in native crestal bone was 62.6 ± 0.4% for N implants and 54.3 ± 0.5% for the O implants (p = 0.001). The collagen fibre density, as assessed by CPLM, was 79.8 ± 6.0 nm for the N group and 74.6 ± 4.6 nm for the O group (p < 0.05). Line scan EDS starting from ABB to newly formed bone showed a decrease in calcium content and an increase of carbon while phosphorus content was constant.

CONCLUSIONS

While the N surface improved the peri-implant endosseous healing properties in the native bone, when compared to the O surface, it did not improve the healing properties in the bone-graft area.

Short implants in maxillary and mandibular rehabilitations: interim results (6 to 42 months) of a prospective study

The aim of this single-cohort study was to evaluate clinical survival and success of partial rehabilitation supported by reduced-length implants in maxilla and mandible. Data from 53 short implants placed in 41 patients are presented. Before surgery mean residual bone height was 6.21 ± 1.05 mm in the upper jaw and 10.73 ± 1.63 mm in the mandible. None of the implants failed, and the cumulative survival rate was 100% at 1 year after prosthetic loading. Mean peri-implant bone loss was 0.69 ± 0.24 mm for maxillary implants and 0.73 ± 0.23 mm for mandibular implants, and there was no significant difference between the 2 jaws. No complications were recorded. Despite the limitations of this study concerning study design and sample size, short implants may be considered effective in supporting partial rehabilitation in both maxilla and mandible. More well-designed studies with a larger sample size and longer follow-up are needed to validate the use of short implants.

Performance of coralline hydroxyapatite in sinus floor augmentation: a retrospective study

OBJECTIVE

The purpose of this study is to retrospectively explore the utilization of coralline hydroxyapatite in maxillary sinus augmentation.

METHOD

One hundred and eighteen cases of sinus lift with coralline hydroxyapatite (CHA) were included in this study. In detail, simultaneous implantation was conducted in 78 patients (174 implants) and delayed implantation was done in 40 cases (82 implants) around 6 months after bone transplantation. The clinical features and X-ray radiographs after operation were analyzed to evaluate osseointegration procedures according to a planned medical follow-up. In the delayed group, around 6 months, a bone biopsy was taken just during implant placement in order to evaluate the new formed bone from a histological and histomorphometrical point of view. A further 6 months later, abutment connection was performed, and the patients received prosthetic restoration of the missing teeth.

RESULT

Clinically, the incisions healed well. No abnormal reactions were found during follow-up period. All the 174 simultaneous implants were successful after 1-5 years of medical review; Out of 82 delayed implants, 3 were found to be loose. Histologically, all the specimens showed signs of active remodeling, and all the tissues had a large amount of osteocyte at sixth month after sinus augmentation. New bone formed dramatically. Radiologically, the density of CHA gradually reduced since the beginning of the third month, and CHA may be completely resolved at about fifth year.

CONCLUSION

CHA is proven an ideal bone graft material for its reliable clinical results and favorable histocompatibility in the treatment of sinus atrophy or other kinds of insufficient bone volume in this region. Moreover, CHA's signal application can achieve desired clinical effect.

CLINICAL RELEVANCE

This study shows the clinic application of CHA in maxillary sinus augmentation. Compared with popular mixture of autogenous bone and grafting materials, our results show CHA's signal application can achieve ideal osseointegration interface and satisfying clinic effect.