The effect of transcrestal sinus-floor elevation without graft on the long-term prognosis of maxillary implants

Radiographic Outcomes of Transcrestal Sinus Floor Elevation With RBH ≤ 5 mm: Non-Perforation and Laterally Repaired Cases

OBJECTIVE

This study aimed to compare the clinical effects of implants placed in sites with a transcrestal sinus floor elevation (TSFE) featuring a residual bone height (RBH) of ≤ 5 mm, without Schneiderian membrane perforations, to those in sites where a lateral window approach was utilized to repair perforations that occurred during TSFE.

METHODS

A total of 104 implants in 80 patients (80 sinuses) with RBH ≤ 5 mm who had undergone TSFE with simultaneous implant placement were included in this retrospective study. The implants were categorized into two groups based on whether the Schneiderian membrane was perforated, and the lateral window technique for sinus floor elevation (LSFE) was utilized to repair perforations that occurred during the TSFE procedure. The early implant loss, endo-sinus bone gain (ESBG), and implant apical bone resorption (ABR) were used to assess new bone formation between the non-perforated and the perforated groups.

RESULTS

The non-perforation group consisted of 89 implants in 69 patients (69 sinuses), whereas the perforated group included 15 implants in 11 patients (11 sinuses). No early implant loss or postoperative complications were observed in either group during the first 6 months following implant installation. The ESBG was (5.83 ± 2.06) mm for the non-perforation group and (7.76 ± 1.63) mm for the perforation-repaired group (p < 0.001). A linear mixed model indicated that group (β = 2.41, 95% CI = 1.49, 3.33, p < 0.001) and RBH (β = -0.53, 95% CI = -0.80, -0.27, p < 0.001) significantly influenced ESBG. The ABR between the non-perforation and perforated group has no statistically significant difference (β = 0.84, 95% CI = -0.41, 2.08, p = 0.185).

CONCLUSION

Repairing Schneiderian membrane perforations that occur during TSFE in cases with RBH ≤ 5 mm, using the lateral window technique, leads to ideal internal radiographic bone augmentation volume maintenance in the maxillary sinus compared to cases without perforation; no significant difference in early implant loss was observed.

TRIAL REGISTRATION

Clinical Trial Registry: (ChiCTR2200062886).

Sinus Bone Graft Stability and Implant Survival Following Transalveolar Sinus Floor Elevation in Severely Atrophic Maxilla: A Retrospective Study With 5-8 Years of Follow-Up

OBJECTIVES

To evaluate the clinical and radiographic results of transalveolar sinus floor elevation (TSFE) with grafting in cases of severely atrophic maxilla.

MATERIALS AND METHODS

A retrospective analysis of clinical and radiographic data was conducted. Between 2015 and 2018, a total of 105 implants were placed in 105 patients over a follow-up period of 5-8 years. Implant failures and endo-sinus bone gain (ESBG) were assessed. Statistical models were established to investigate the potential influencing factors of implant survival and ESBG.

RESULTS

Six patients with six implants were lost, resulting in cumulative survival rates of 94% for both patient- and implant-based analyses. The 8-year cumulative survival rate was significantly lower for residual bone height (RBH) < 4 mm (88%) compared to RBH 4-6 mm (98%). ESBG ≥ 4 mm and ESBG ≥ 6 mm were observed in 89.90% and 58.59% of implant sites, respectively. According to the log-rank Mantel-Cox analysis results, none of the factors examined were significantly related to implant failure, except for RBH (p = 0.038) at baseline. The linear mixed-model regression results showed that the final ESBG was positively correlated with implant insertion site (p = 0.003), implant length (p < 0.001), sinus floor elevation (SFE) methods (p = 0.010), and RBH (p < 0.001).

CONCLUSIONS

Within the limitations of this study, it has been established that TSFE with grafting was a reliable method for implant placement in the posterior atrophic maxilla ridges with RBH ranging from 4 to 6 mm. Nevertheless, caution was advised when considering its application in cases where the initial bone height falls below 4 mm.

Impact of Vertical Inter-Implant Distance in Two Adjacent Single-Unit Posterior Implants: A Retrospective Cohort Study With 1-8 Years of Follow-Up

AIM

To investigate the impact of different vertical interimplant distances (VIDs) on the long-term success of two adjacent single-unit implants.

MATERIALS AND METHODS

This retrospective study categorized implants into two groups based on VID: Group 1 (VID < 2 mm) and Group 2 (VID ≥ 2 mm). Further classification was done according to horizontal inter-implant distance (HID). Statistical models were used to evaluate the primary outcome of implant survival, secondary outcomes of complication-free survival rates and radiological findings.

RESULTS

We included 290 patients with 376 two adjacent single-unit implants. Group 1 included 223 patients with 280 implants, whereas Group 2 comprised 89 patients with 96 implants. The implant survival rates were 93.2% in Group 1 and 96.8% in Group 2 over the 8 years, with no significant association between the groups. Similarly, the overall complication-free survival rates were 60.6% in Group 1 and 65.6% in Group 2, showing no significant association between the groups. Radiological assessments also showed no notable association between the groups. This trend was consistent in the subgroup analyses based on HID, with no significant differences in implant survival, complication-free survival rates or radiological outcomes.

CONCLUSIONS

Considering the study limitations of an 8-year post-prosthetic review period and despite varying VIDs, our findings showed no significant difference in implant survival, complication-free survival rates or radiological assessments. This underscores the positive prognosis of two adjacent single-unit implants and contributes to a deeper understanding of the success factors in implantology.

TRIAL REGISTRATION

The study was registered in the Chinese Clinical Trial Registry (ChiCTR2300073215).

APCs in sinus floor augmentation

After tooth loss in the posterior area of the maxilla, sinus floor elevation is often required to compensate the vertical bone loss due to sinus pneumatization. This narrative review reports on the potential benefits of autologous platelet concentrates (APCs) during this procedure. As for transcrestal approach, APCs have been used as "sole" substitute/graft. However, because of the low number of clinical trials available with PRGF, and even none for PRP, no definitive conclusions can be made regarding their efficacy. The number of studies on the use of L-PRF were outnumbered indicating good feasibility for vertical bone gain, with a high implant survival rate and a low degree of complications. PRP and PRGF have not been studied as a "single/sole" substitute for a one-stage lateral window approach, probably because of the weak physical characteristics of the membranes. L-PRF alone appears to be a predictable grafting material for lateral maxillary sinus grafting and a reduced RBH should not be considered as a risk factor. Compared to a "standard" bone substitute L-PRF shows slightly less vertical bone gain (consider enough membrane application and use of bony window as new sinus floor roof over the implant apices), enhanced early resorption (first 6 months after application), but a similar stable bone gain afterward. For a two-stage lateral window approach, APCs "alone" cannot be recommended, due to their weak withstand to the sinus pneumatization forces. APCs combined with bone substitutes seem to accelerate bone formation, without any additional benefits on the long-term new bone gain. The use of L-PRF membranes for the treatment of perforations appears to be an effective treatment option, but further clinical studies are needed to confirm this. Even though the abovementioned statements are based on large numbers of studies, additional RCTs comparing APCs with different types of grafting procedures for sinus elevation are needed.

Three-dimensional changes and influencing factors of tent space following osteotome sinus floor elevation without grafting: A 48-month retrospective radiographic study

OBJECTIVES

To analyze the three-dimensional stability and morphologic changes of tent space after the osteotome sinus floor elevation (OSFE) procedures without bone grafts.

MATERIALS AND METHODS

Forty-six implants placed using the OSFE technique with simultaneous implant placement without bone grafts were included in this retrospective study. Cone-beam computed tomography (CBCT) scans of the augmented sinuses were obtained pre- and postoperatively up to 48 months of follow-up. The maxillary sinus cavity profiles were outlined using three-dimensional virtual reconstruction and superimposition of CBCT scans. The three-dimensional changes in the tent space were measured. A generalized estimating equation (GEE) was used to explore potential factors.

RESULTS

The implant survival rate was 97.8%. The mean volume of remaining tent space immediately after surgery was 96.8 ± 70.5 mm3, shrinking to 31.0 ± 24.9 mm3 after 48 months, while the mean percentage of remaining tent space volume decreased to 29.1 ± 20.7%. The tent space volume and the percentage of residual tent space volume only decreased significantly within 12 months after surgery (p = .008, .013). GEE results indicated positive correlations between the percentage of remaining tent space volume and implant protrusion length (p = .000) and apical height (p = .000), with a negative correlation between the sinus floor area immediately after surgery (p = .002) and the healing time (p = .022).

CONCLUSIONS

The volume of the tent space rapidly shrank after OSFE without bone grafts. Several factors might influence the tent space stability. Long-term clinical trials with larger sample sizes are necessary to further validate the results.

Risk Factors for Implant Failure Following Transcrestal Sinus-Floor Elevation: A Case Report and Literature Review

Although transcrestal sinus floor elevation (TSFE) is widely used for cases of insufficient residual bone height in the posterior maxilla, few studies focus on the risk factors of early implant failure associated with TSFE procedures. This study aimed to identify and summarize the possible risk factors of implant failure associated with TSFE to ensure a more predictable implant survival rate using TSFE. We report the treatment of a patient with implant failure following TSFE and discuss this case's possible associated risk factors. A standard implant with a diameter of 4.8 mm and length of 10 mm was used after the TSFE procedure. Implant loosening was suddenly observed 6 weeks after the initial surgery. Factors that could result in early implant failure included patient-related risk factors, anatomical factors of the operational area, and operation- and implant-related factors. Within the current study's limitations, the graft material particles between the implant surface and socket could be considered a direct risk factor resulting in implant failure. Therefore, more attention should be paid to socket cleaning during the TSFE procedure, and loose particulate grafting materials should be discouraged. Another significant consideration for implant loss is the possibility of fractures in the buccal or palatal cortical plates during the site preparation and implant insertion. Thus, these factors should be studied further and receive more clinical attention.

[Graftless maxillary sinus lift with simultaneous implant placement: a case report]

A maxillary sinus lift was performed without bone grafting in a 23-year-old female patient who required the placement of a dental implant in the edentulous area of tooth 16. The clinical and tomographic evaluation made it possible to plan and perform the maxillary sinus lift using the transcrestal approach and without the need for bone grafting. The residual ridge of 6mm allowed the placement of a simultaneous dental implant. After 6 months of tomographic follow-up, before prosthetic loading, a vertical bone height of 8.83 mm was achieved, resulting in a vertical bone gain of 2.83 mm. Additionally, an adequate integration of the dental implant was observed without postoperative complications. Transcrestal sinus lift without the use of bone graft is shown to be a viable, safe and effective technique for the simultaneous placement of dental implants in patients with bone atrophy in the maxillary area. This technique offers advantages such as reduced surgical time, less morbidity, lower cost and a faster healing process compared to conventional methods.

Analysis of the accuracy of a dynamic navigation system when performing dental implant surgery with transcrestal sinus floor elevation: A pilot study

Background/purpose

The success of transcrestal sinus floor elevation (TSFE) is primarily reliant upon the experience of the surgeon owing to the limited operative visibility. To evaluate the accuracy associated with the use of a dynamic navigation system when conducting posterior maxilla implant surgery with TSFE.

Materials and methods

Twenty-eight implants were placed in 28 patients requiring implantation in the posterior maxilla via a TSFE approach. The drills were used to access the planned position (within 1 mm of the bottom of the maxillary sinus floor) under dynamic navigation system. TSFE was then accomplished using osteotomes and a piezoelectric device. Lastly, the implant was inserted under the dynamic navigation. Three effective deviations between planned and actual implant placement were then measured including angular deviation (AD, degrees), entry point horizontal deviation (EPHD, mm), and apical point horizontal deviation (APHD, mm).

Results

The AD, EPHD, and APHD between the planned and actual implant placement were 3.656 ± 1.665°, 1.073 ± 0.686 mm, and 1.086 ± 0.667 mm, respectively. Premolar site AD values were less than those for molar sites (P = 0.004). No significant differences in these outcomes were observed in different surgeons. Obvious sinus perforation was not detected by immediate postoperative cone beam computed tomography imaging.

Conclusion

The accuracy associated with using a dynamic navigation system when conducting posterior maxilla implant surgery via a TSFE approach using piezoelectric devices was comparable. This technique thus achieved appropriate interventional precision and safety while decreasing the morbidity associated with the TSFE approach.

Effectiveness and complications of transcrestal sinus floor elevation using the cushioned grind-out technique: A retrospective cohort study with up to 7 years of follow-up

AIM

To evaluate the effectiveness and complications of the cushioned grind-out technique. The primary outcome was endo-sinus bone gain (ESBG), while secondary outcomes included the Schneiderian membrane perforation rate and mid- to long-term implant survival.

MATERIALS AND METHODS

In this retrospective study, we compared the cushioned grind-out technique with the classic osteotome technique, establishing statistical models to assess ESBG, membrane perforation rate and implant survival rate.

RESULTS

A total of 259 patients and 340 implants were included. The mean ESBG was 5.31 mm for the cushioned grind-out group and 4.64 mm for the osteotome group. Multivariable regression analysis revealed that the cushioned grind-out technique significantly facilitated ESBG (p = .028). Nineteen preparation sites experienced membrane perforation, with rates of 5.5% and 6.4% for the cushioned grind-out and osteotome groups, respectively. However, the difference was not statistically significant (p = .920). Additionally, the cumulative survival rate of the implants for 7 years was 95.2% and 91.4%, respectively, with the surgical technique not significantly influencing the results.

CONCLUSIONS

With 6 months to 7 years of post-prosthetic restoration review data, our findings show that the cushioned grind-out technique facilitates a higher ESBG, with no significant difference in membrane perforation or implant failure rate.

Implant failure and associated risk factors of transcrestal sinus floor elevation: A retrospective study

OBJECTIVES

This retrospective study aimed to evaluate early and late implant loss rates after transcrestal sinus floor elevation (TSFE) and to identify the risk factors related to these failures.

MATERIAL AND METHODS

All patients treated with TSFE and simultaneous implant placement during October 2015 to March 2019 were evaluated for inclusion. A total of 802 patients with 976 implants met the inclusion criteria. Clinical and radiographic information was collected from medical records and image software. Univariate and multivariate Cox proportional hazards frailty regression models were performed to identify potential risk factors associated with early and late implant loss after TSFE.

RESULTS

The 3-year cumulative implant survival rate was 96.9% (95% CI 95.8%-98.0%). Twelve implants in 12 patients were lost before or at the abutment connection, while 24 implants in 24 patients were lost after functional loading. The Cox frailty regression analyses indicated that two factors were correlated with early implant loss: TSFE with grafting materials, and operators with less clinical experience. As for late implant loss, RBH ≤6 mm, male sex, and certain implant brands were associated with a significantly increased failure rate.

CONCLUSIONS

Transcrestal sinus floor elevation with simultaneous implant placement is a predictable treatment option in the atrophic maxilla. The presence of grafting materials and the lack of clinical experience of the surgeon were possibly associated with early implant loss, while low RBH, male sex, and certain implant brands tended to increase late implant loss.

Factors impacting new bone formation in transcrestal sinus floor elevation followed by implant placement: a cross-sectional study

Objectives

This study aimed to evaluate factors related to new bone formation (NBF) following simultaneous implant placement with transcrestal sinus floor elevation (TSFE).

Materials and methods

Between 2008 and 2020, 357 implants (276 patients) were placed with TSFE. Clinical and radiographic examinations were performed at the preoperative, postoperative, restoration, and follow-up stages. Marginal bone loss, during healing, and the survival rate were retrospectively analyzed.

Results

Implant protrusion lengths (IPL: 3–5 mm) significantly influenced NBF during the healing period (P-value = 0.026, Odds Ratio = 1.15, 95% confidence interval = 1.02- 1.30). Bone grafting was correlated with NBF (P-value = 0.001). The distance between the implant and lateral wall of the sinus (mesial: P-value = 0.041, distal: P-value = 0.019, buccal: P-value = 0.032, lingual: P-value = 0.043) and angle between the implant and sinus floor significantly influenced NBF in four directions (mesial: P-value = 0.041, distal: P-value = 0.02, buccal: P-value = 0.047, lingual: P-value = 0.005). Implant shape (cylindrical or conical), perforations, smoking, and diabetes did not significantly affect NBF during the healing period (P > 0.05).

Conclusion

Increasing the distance and angle between the implant and lateral wall of the sinus floor corresponded with reduced NBF. IPL may be an important factor that should be considered.

Clinical relevance

Our study analyzed new bone formation following transcrestal sinus floor elevation among patients who underwent this procedure with simultaneous implant placement, several factors (including angle and distance between sinus and lateral wall and implant protrusion length) were included in our study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02352-6.

Maxillary sinus floor augmentation comparing removing versus retaining antral pseudocyst: A retrospective cohort study

OBJECTIVES

To retrospectively compare multilevel volumetric changes in both hard and soft tissues between antral pseudocyst (AP) removal and retainment before maxillary sinus floor augmentation (MSFA) and immediate implant placement.

MATERIAL AND METHODS

Twenty-six patients with thirty-eight implants placed from 2016 to 2021 were included and divided according to a cohort design as follows: 13 removing the cyst (RC group) and 13 "leaving alone" the cyst (LC group). 3D radiographic parameters (primary outcome), 2D parameters and clinical records (secondary outcome) involving both hard and soft tissues were evaluated for 4 periods (T1: immediate postoperative, T2: 6-month, T3: 12-month, and T4: 2- to 5- year follow-up). Possible confounding factors, including sinus anatomical features and implant distribution, were also analyzed to eliminate their disturbance.

RESULTS

The 3D volumetric change rate of bone grafts in the RC group (-9.32 ± 10.01%) from T2 to T3 was significantly lower than that in the LC group (-19.8 ± 10.59%) (p < .05). The change rate of apical bone height (ABH), endo-sinus bone gain (ESBG) and other 2D parameters were not significantly different between the two groups. 5.3% implants in RC group and 9.1% implants failed during follow-ups. 0% postoperative complications were observed in RC group. The Schneiderian membrane of RC group was significantly thinner than that of LC group at two measuring points in sinus.

CONCLUSION

The present study demonstrated that compared to AP retainment, AP removal before MSFA and immediate implant placement can obtain higher bone graft volumetric stability and favorable prognosis. The study protocol was approved by the Medical Ethics Committee of the Affiliated Hospital of Stomatology, School of medicine, Zhejiang University, China (Acceptance number: 2021-117(R)).

Intraoperative complications and early implant failure after transcrestal sinus floor elevation with residual bone height ≤5 mm: A retrospective multicenter study

OBJECTIVE

Clinical indications for maxillary sinus floor elevation with transcrestal techniques have increased in recent years even in sites with minimal residual bone height (RBH). Nevertheless, limited information is currently available on incidence of intraoperative complications and early implant failure in these cases.

MATERIAL AND METHODS

This retrospective multicenter study was performed on anonymized clinical and radiographic records of patients who underwent transcrestal sinus floor elevation in seven clinical centers. Influence of different factors related to patient, and sinus anatomy and surgical technique on the incidence of intraoperative complications and early implant failure rate after transcrestal sinus lift were investigated.

RESULTS

A total of 430 patients treated with transcrestal sinus floor elevation for single-implant insertion in sites with RBH ≤5 mm were included in the final analysis. After 1 year of loading, 418 implants of 430 were satisfactorily in function. Early implant failure was recorded in 12 cases (2.8%); results were significantly associated with the presence of large sinus cavities and with the occurrence of membrane perforation. The following adverse events were recorded: membrane perforation (7.2%), acute sinusitis (0.9%), implant displacement into the sinus cavity (0.7%), oro-antral fistula (0.2%), and benign paroxysmal positional vertigo (0.5% of osteotome cases). A strong direct correlation between sinus membrane perforation and bucco-palatal sinus width (p = .000) was demonstrated.

CONCLUSIONS

Early implant failure after transcrestal sinus elevation showed significant direct correlation with bucco-palatal maxillary sinus width and the presence of membrane perforation. Sinus membrane perforation was strongly associated with bucco-palatal sinus width (extremely low perforation rate in narrow and much higher incidence in wide sinuses).

Digital Workflow for the Design, Manufacture, and Application of Custom-Made Short Implants With Wing Retention Device

The severe deficiency of vertical bone height in the posterior maxillary region poses a challenge to implant restoration. In response to this issue, this article introduces a custom-made short implant with a wing retention structure and describes a precise and minimally invasive dental implant restoration scheme with digital technology.

Sinus floor elevation and simultaneous implant placement in fresh extraction sockets: a systematic review of clinical data

Combining different procedures to reduce the number of surgical sessions and patient discomfort in implant placement and sinus floor elevation has been recommended, and evidence supports good outcomes. The aim of this study was to review the results of clinical studies on sinus floor elevation through extraction sockets and simultaneous immediate posterior implant placement. An electronic search was carried out in PubMed, Scopus, and Web of Science to find English articles published in or before August 2020. A manual search was also performed. Titles, abstracts, and the full-text of the retrieved articles were studied. Thirteen studies met our eligibility criteria: 6 retrospective case series, 3 case reports, 2 prospective cohort caseseries, 1 prospective case series, and 1 randomized controlled trial. Overall, 306 implants were placed; 2 studies reported implant survival rates of 91.7% and 98.57%. The others either did not report the survival rate or reported 100% survival. Sinus floor elevation through a fresh extraction socket and simultaneous immediate implant placement appears to be a predictable modality with a high success rate. However, proper case selection and the expertise of the clinician play fundamental roles in the success of such complex procedures.

Maxillary implant overdentures on two or four implants. A prospective randomized cross-over clinical trial of implant and denture success and survival

OBJECTIVES

To determine implant survival and success of four conventionally but initially asynchronously loaded implants in implant-supported overdentures for the edentulous maxilla, in participants with opposing mandibular two-implant overdentures.

MATERIAL AND METHODS

Twenty-six participants received four implants in the region of the maxillary canines and molars. After healing, 24 of these participants (mean age: 68.3 years) were randomly allocated to one of two treatment groups, and the adapted overdenture was attached to two unsplinted cylindrical attachments. The other two matrixes remained unattached to the implants for 3 months. After this period, the other two implants were loaded for 3 months (cross-over design). Then, all four implants were loaded for another 3 months. Kaplan-Meier curves were used to evaluate survival and success of implants and dentures.

RESULTS

During the active prosthetic study phase, three participants lost one implant. Two participants lost three implants during the recall period. Implant survival after loading was 93.8% after a mean observation period of 3.1 years. Denture survival was 100%, but denture success was 95.8%, due to major prosthetic complications. Most participants preferred four implants to two.

CONCLUSIONS

Within the limitations of the study, it can be concluded that maxillary implant overdentures on two or four implants are both recommendable treatment options. Two posterior implants are not superior to two anterior implants under overdentures retained by unsplinted cylindrical attachments. Implant and prosthetic complications and aftercare measures are common but are mostly easy to handle. However, 23 of the 24 participants preferred the 4-implant maxillary overdenture.

Effect of previous implant failure on the prognosis of subsequent implants: A retrospective study

OBJECTIVES

To compare the long-term survival of dental implants placed in patients with and without a history of implant failure.

MATERIAL AND METHODS

Within a retrospective analysis, an experimental group was selected consisting of 59 patients with 137 implants placed after previous failure. The control group included 1,072 patients with 2,664 implants without previous failure. Kaplan-Meier curves were used to describe the group-specific long-term implant survival. Mixed-effects Cox regression models were applied to examine the effects of patient- and site-specific risk factors. To take multiple implants into account, a random intercept model was applied.

RESULTS

During the observation period of up to 15 years, 11 implants (8%) failed in the experimental group and 74 implants (2.5%) in the control group (p < .001). Five-year cumulative survival was 96.8% (95% CI 0.96-0.98) in the control group and 91.5% (95% CI 0.86-0.97) in the experimental group. The variables group assignment and simultaneous augmentation had a significant effect on survival, but this effect was lost in the random intercept model. The effect of implant location remained, whereby the risk of failure was five times lower for mandible implants, irrespective of group (p = .013; 95% CI 0.103-0.767; HR: 0.281).

CONCLUSIONS

Long-term implant survival was lower in the experimental group than in the control group. The effect of previous failure was negligible. However, a patient-specific "clustering effect" was observed. Irrespective of previous implant failure, the risk of long-term failure is two times higher for maxillary implants than for mandibular implants.

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.

Sinus mucosa thinning and perforation after sinus augmentation. A histological study in rabbits

AIM

To evaluate the modifications and possible perforations of the sinus mucosa lining graft particles and implant surfaces after sinus lifting.

MATERIAL AND METHODS

Twelve New Zealand rabbits underwent a bilateral sinus lifting using either autogenous bone harvested from the tibia (AB; autogenous bone group) or deproteinized bovine bone mineral (DBBM group) as filler. Implants were simultaneously installed. Thinned sites (<40 μm) and perforations were histologically evaluated at the sinus mucosa in contact with the graft and with the implant after 7 and 40 days of healing.

RESULTS

The mean width of the pristine mucosa was ~70-80 μm. After 7 days of healing, the sinus mucosa in contact with the graft presented fourteen thinned sites in the AB group (mean width 28.8±12.8 μm) and fifty-nine in the DBBM group (mean width 22.2±5.2 μm). No perforations of the mucosa were seen in the AB group while six perforations distributed in two sinuses were found in the DBBM group. After 40 days, only one thinned mucosa and no perforations were observed in the AB group while ninety-six thinned mucosa sites were shared by six sinuses (19.2±3.8 μm), and 3 perforations by two sinuses in the DBBM group. Few sites of the mucosa were in contact with the implant apex and threads after 7 days of healing. However, after 40 days, twelve thinned mucosa sites were seen in four sinuses in the AB groups (mean width ~19 μm) and 5 in two sinuses in the DBBM group (mean width ~20 μm). Perforations were seen in two sinuses in the AB group, and in one sinus in the DBBM group.

CONCLUSIONS

The sinus mucosa might be damaged by a close contact with graft particles and implant surface.

Long-term outcomes of osteotome sinus floor elevation without grafting in severely atrophic maxilla: A 10-year prospective study

OBJECTIVE

The aim of the present study was to report 10-year results of osteotome sinus floor elevation (OSFE) without grafting severely atrophic maxilla (residual bone height ≤4 mm).

MATERIALS AND METHODS

Patients undergoing OSFE without grafting and implant placement were included for 10-year examinations. Implant survival, complication-free survival, modified bleeding index (mBI), modified plaque index (mPI), pocket probing depth (PPD), peri-implant marginal bone loss (MBL), endo-sinus bone gain (ESBG) and mean cost of recurrence were evaluated.

RESULTS

Overall, 23 patients with 35 implants attended 10-year examination. Cemented implant crowns or implant-supported fixed dental prostheses were delivered to the patients. Kaplan-Meier implant survival was 89.2% at implant level and 84.1% at patient level. Complication-free survival was 26.0% at patient level and 37.0% at implant level. The average complication-free survival time was 74.6 months (95% CI: 63.2-86.0 months) at implant level and 69.1 months (95% CI: 54.8-83.4 months) at patient level. The mBI, mPI, PPD, MBL and ESBG at 10-year follow-up were 0.91 ± 0.58, 0.48 ± 0.51, 2.94 ± 0.79 mm, 1.63 ± 0.83 mm and 2.72 ± 0.51 mm, respectively. The cost of managing recurrence was 43.6% of the initial cost of treatment.

CONCLUSION

The results of the present study indicate that OSFE without grafting is a reliable treatment option in severely atrophic maxilla. Acceptable survival rate, stable MBL and ESBG could be achieved within 10 years. Low complication-free survival and high costs of recurrence management need to be considered.

Long-term apical bone gain after implant placement combined with internal sinus-floor elevation without graft

BACKGROUND

To assess changes in apical bone height/bone gain over up to 8 years after implant placement combined with simultaneous internal sinus-floor elevation (ISFE) without use of graft.

METHODS

217 implants were placed in combination with graft-free ISFE and successfully healed in the posterior maxilla of 138 patients. Radiographs after surgery across an evaluation time of up to 8 years were analyzed. Changes in apical and marginal bone height related to the implants were measured. Differences in bone height over the study period were evaluated by use of Wilcoxon tests. To identify possible influencing factors on apical bone gain and marginal bone loss, backward linear regression variable selections and linear mixed regression models were performed.

RESULTS

At the apical aspects of the implants, significant mean vertical bone gain of 2.4 mm (mesial) and 2.6 mm (distal) was observed after 6 months (p < 0.05). Radiographic analysis yielded additional bone gain of up to approximately 3.5 mm over the study period. Small initial bone height was crossed with more pronounced apical bone gain (p < 0.05).

CONCLUSIONS

If implants are placed combined with graft-free ISFE, significant vertical bone gain, especially in the first year post-op, can be expected. Smaller initial bone height is associated with a higher likelihood for greater bone gain.