Interpositional Osteotomy for Posterior Mandible Ridge Augmentation

Survival Rate of 1008 Short Dental Implants with 21 Months of Average Follow-Up: A Retrospective Study

This retrospective study evaluated the survival rate of short, sandblasted acid-etched surfaced implants with 6 and 8 mm lengths with at least 120 days of follow-up. Data concerning patient, implant and surgery characteristics were retrieved from clinical records. Sandblasted and acid-etched (SLA)-surfaced tissue-level 6 mm (TL6) or 8 mm (TL8) implants or bone-level tapered 8 mm (BLT8) implants were used. Absolute and relative frequency distributions were calculated for qualitative variables and mean values and standard deviations for quantitative variables. A Cox regression model was performed to verify whether type, length and/or width influence the implant survival. The cumulative implant survival rate was assessed by time-to-event analyses (Kaplan–Meier estimator). In all, 513 patients with a mean age of 58.00 ± 12.44 years received 1008 dental implants with a mean follow-up of 21.57 ± 10.77 months. Most implants (78.17%) presented a 4.1 mm diameter, and the most frequent indication was a partially edentulous arch (44.15%). The most frequent locations were the posterior mandible (53.97%) and the posterior maxilla (31.55%). No significant differences were found in survival rates between groups of type, length and width of implant with the cumulative rate being 97.7% ± 0.5%. Within the limitations of this study, the evaluated short implants are a predictable option with high survival rates during the follow-up without statistical differences between the appraised types, lengths and widths.

Extramaxillary Zygomatic Implants: An Alternative Approach for the Reconstruction of the Atrophic Maxilla

Background

Limited bone quality in the posterior maxilla results in low success rates for dental implants. Various bone augmentation methods have been described, yet most require two-step surgical procedures with relatively high rates of resorption and failure. An alternative for these patients is zygomatic implants. Zygomatic implants utilize the basal craniofacial bone.

Materials and Methods

A retrospective study was conducted on 25 patients exhibiting ridges classified as V-VI according to the Cawood and Howell classification. Seventy-six extramaxillary zygomatic implants were placed. Immediate rehabilitation was performed with a mean follow-up of 18.6 months.

Results

Three implants failed, and two were replaced successfully. No significant bone loss was observed in the rest of the implants. Soft tissue around the implant heads healed properly. All implants were prosthetically rehabilitated successfully.

Conclusions

Zygomatic implants allow for immediate loading of an atrophic maxilla. The emergence of the implant is prosthetically correct compared to the intrasinus approach, leading to better dental hygiene and decreased mechanical resistance. 96.1% of the implants survived, with good anchorage and proper soft tissue healing and rehabilitation. We suggest using extramaxillary zygomatic fixture as the first line of treatment in severe atrophic maxilla.

Sandwich osteotomy of the atrophic posterior mandible with interpositional autogenous bone block graft compared with bone substitute material: a systematic review and meta-analysis

The objective of the present systematic review was to test the hypothesis that there were no differences in outcome of implant treatment after sandwich osteotomy in the atrophic posterior mandible with interpositional autogenous bone block graft, compared with bone substitute material. A MEDLINE/PubMed, Embase and Cochrane Library search in combination with hand-search of selected journals was conducted. Two short-term randomised controlled trials with a split-mouth study design and low risk of bias fulfilled the inclusion criteria. High survival rate of suprastructures and implants was disclosed with no significant difference between interpositional autogenous bone block graft compared with bone substitute material. Meta-analysis revealed patient-based implant survival risk ratio of 1.05 (95% CI: 0.88 to 1.25) and peri-implant marginal bone loss of 0.31mm (95% CI: -0.29 to 0.90) indicating no significant differences between the two treatments. High implant stability values, gain in vertical alveolar ridge height, bone formation, and few complications were reported with both treatments. Sandwich osteotomy with interpositional grafting material appears to be a predictable surgical technique for enhancement of the vertical alveolar ridge height in the atrophic posterior mandible prior to implant placement.

Pedicled segmental rotation techniques for posterior mandible augmentation: a preliminary study

Rehabilitation of the atrophic posterior mandible is a challenge in dental practice. Conventional treatments include the segmental sandwich osteotomy or inlay bone grafting (IBG), onlay bone grafting (OBG), short implants, distraction osteogenesis, and inferior alveolar nerve transposition (IANT), each with its downsides. This case series is reported to introduce a modification of IBG - pedicled segmental rotation (PSR) for the reconstruction of co-existing vertical and horizontal defects in the posterior mandible. Ten healthy patients with vertical-horizontal defects (no vertical bone walls and basal bone width <5 mm) were included. Posterior mandibular defects were treated with PSR, PSR + IANT, or PSR + OBG. In PSR, a pedicle-preserved segment is up-fractured superiorly and then flipped 90° to a vertical position. The segment is then supported with inorganic bovine bone and autogenous bone particulates. Cone beam computed tomography was performed preoperatively and at the 4-month follow-up, in addition to clinical examinations. Soft tissue healing was uneventful. Radiomorphometric analysis showed a mean new bone volume of 647.79 ± 81.31 mm³ (ΔH = 7.13 mm), 836.99 ± 119.14 mm³ (ΔH = 7.8 mm), and 640.20 ± 50.13 mm³ (ΔH = 6.59) in the PSR, PSR + OBG, and PSR + IANT groups, respectively. The proposed PSR technique used in this case series showed promising results for vertical and horizontal augmentation of the atrophic posterior mandible before placement of dental implants.

In-Site Monocyte Implantation in Bone Grafting for Maxillary Atrophy Reconstruction: A Preliminary Observational Proof of Concept Study

PURPOSE

The main objective of this study, involving 11 patients, is to share our experience on an integrated treatment modality, namely, the use of cellular therapy simultaneously with surgical reconstruction. Published works show that the implantation of monocytes in ischemic tissue enhances healing by providing neo-angiogenesis, a key mechanism in tissue regenerative processes.

MATERIALS AND METHODS

Our approach included the utilization of autologous monocytes and endothelial precursor cells in the bone graft itself to improve the success rate of the integration of the bone graft and its long-term viability/survival by promoting angiogenesis. We compared the standard regenerative procedures, namely sinus lift grafting performed with xenogeneic particle bone graft and posterior mandible grafting performed with on-lay or in-lay autologous cortical/medullary bone-block graft harvested from the iliac crest, with and without the use of cellular implementation. We evaluated results by both radiological and histological assessment.

RESULTS

Autologous cortical/medullary bone-block graft had a different response to implementation with monocytes, showing a better osteointegration than expected conversely to the xenogeneic particle bone graft.

CONCLUSIONS

Monocytes seem to improve autologous bone-block graft according to the "Therapeutic Angiogenesis" concept. Implementation with monocytes does not always improve xenogeneic particle bone graft.

Clinical Success of Dental Implants Placed in Posterior Mandible Augmented With Interpositional Block Graft: 3-Year Results From a Prospective Cohort Clinical Study

PURPOSE

The purpose of the present cohort study was to investigate the 3-year efficacy and clinical performance of implant-supported rehabilitations in posterior mandibles augmented with the sandwich osteotomy technique.

MATERIALS AND METHODS

Twenty-three partially edentulous patients who developed atrophy of the posterior mandible (residual ridge height, 3 to 7 mm) were treated (32 surgical sites) with vertical bone augmentation using interpositional equine cancellous bone blocks and porcine corticocancellous bone particulate. All implants were placed 4 months after augmentation and were loaded with fixed dental prostheses. One side per patient was selected and followed for 3 years, and the patient was the unit of analysis. Linear radiographic vertical bone gain and peri-implant marginal bone loss were assessed; secondary outcomes-complication rates after surgery, prosthesis and implant failure rates, width of keratinized mucosa, and patient satisfaction-were evaluated.

RESULTS

All patients reported postoperative paresthesia that resolved over a period of 2 months after the augmentation procedure. The mean vertical bone gain was 5.6 mm after 4 months. Ninety-one dental implants were positioned into the augmented areas. The global 3-year survival rate was 95.5%. The mean peri-implant marginal bone loss around implants was 1.06 ± 0.37 mm 3 years after loading, whereas the width of keratinized mucosa had an overall increase of 0.39 ± 0.36 mm.

CONCLUSION

The results of the present 3-year study suggested high success rates for implants placed in areas augmented with the osteotomy sandwich technique. This surgical approach could be helpful in the presence of a low residual vertical height in the posterior mandible before implant placement.

Early volumetric changes after vertical augmentation of the atrophic posterior mandible with interpositional block graft versus onlay bone graft: A retrospective radiological study

PURPOSE

The aim of this study was to evaluate volumetric and clinical outcomes of atrophic posterior mandibles treated with inlay or onlay bone grafting techniques.

MATERIALS AND METHODS

In posterior mandibles, alveolar ridges were treated either with interpositional equine cancellous bone block (inlay group) or with onlay autogenous bone block (onlay group). Bone volumes at baseline and at 4 months after surgery were measured by computed tomography.

RESULTS

A total of 20 subjects were enrolled in the present study: 10 in the inlay group and 10 in the onlay group. After surgery, atrophic posterior mandibles showed a mean vertical augmentation height of 6.0 mm in the inlay group and 7.4 mm in the onlay group. No significant differences were recorded between the two groups regarding volume loss of the grafted bone or decrease in vertical bone height of the augmented site (29% and 1.9 mm for the onlay group, and 35% and 1.7 mm for the inlay group) during healing. Two complications (1 wound dehiscence and 1 mandibular fracture) occurred postoperatively in the inlay group; on the other hand, the onlay group had three complications (wound dehiscence). A total of 80 dental implants were placed in augmented areas: 46 in the inlay group with a peri-implant marginal bone loss of 0.8 mm, and 34 in the onlay group with a peri-implant marginal bone loss of 1.3 mm (p = 0.0006).

CONCLUSIONS

Inlay xenogeneic grafts showed volumetric bone remodeling similar to that recorded for onlay autogenous bone. The success of the autogenous onlay blocks (82.4%) appeared to be lower than that registered for the inlay group (93.8%), but the difference was not significant.

Vertical Alveolar Distraction Osteogenesis of the Atrophic Posterior Mandible Before Dental Implant Insertion

PURPOSE

Augmentation of deficient mandibular posterior alveolar ridges poses a great challenge because of extensive bone deficiency and the presence of the inferior alveolar nerve. This study sets its focus on vertical alveolar distraction osteogenesis (ADO) at the posterior mandible before dental implant placement.

MATERIALS AND METHODS

The study included 21 sites in 18 patients with severe mandibular posterior alveolar ridge deficiency. A trapezoidal osteotomy was performed, and an extraosseous alveolar distraction device was fixed and activated after a 4-day latency period at a rate of 0.5 mm/day. After a 4-month retention period, the distraction device was removed and titanium dental implants were placed.

RESULTS

A mean vertical augmentation of 14.47 mm was gained. The newly formed bone was shown using panoramic radiography and computed tomography. We placed 56 dental implants, and during a minimum follow-up period of 36 months, 2 implants were lost, resulting in a success rate of 96.42%.

CONCLUSIONS

ADO offers marked vertical ridge augmentation with simultaneous soft tissue expansion and stable results. ADO diminishes the need for autogenous bone graft, thus sparing donor-site morbidity. ADO of the deficient posterior mandibular alveolar ridge is useful in moderate to severe bony deficiencies and allows for adequate bone formation, which allows implant insertion.

Segmental sandwich osteotomy of the posterior mandible in pre-implant surgery - A systematic review

Background

The rehabilitation of the atrophic posterior mandible with dental implants often requires bone augmentation procedures. The aim of the present study is the systematic review of the literature concerning the success rate of Segmental Sandwich Osteotomy (SSO) of the posterior mandible in pre-implant surgery.

Material and Methods

Systematic review of all clinical cases and clinical studies of SSO of the posterior mandible in pre-implant surgery with a minimum follow-up of 6 months after implant loading was performed, based on specific inclusion and exclusion criteria. The search strategy involved searching the electronic databases of MEDLINE, EMBASE, COCHRANE LIBRARY, Clinical Trials (www.clinicaltrials.gov) and National Research Register (www.controlled-trials.com), supplemented by a manual search, in August 2015. In every study, the intervention characteristics and the outcome were recorded.

Results

Out of the 756 initial results, only 17 articles fulfilled the predetermined inclusion and exclusion criteria. They consisted of 9 retrospective case reports or series and 8 prospective randomized clinical trials. Overall, the studies included 174 patients. In these patients, 214 SSO augmentation procedures were performed in the posterior mandible and 444 implants were placed. The follow-up period after implant loading ranged between 8 months and 5.5 years. The success rate of SSO ranged between 90% and 100%. The implant survival during the follow-up period ranged between 90.9% and 100%.

Conclusions

Segmental Sandwich Osteotomy should be considered as a well documented technique for the rehabilitation of the atrophic posterior mandible, with long-term postsurgical follow-up. The success rates are very high, as well as the survival of the dental implants placed in the augmented area.

Key words:Segmental osteotomy, dental implant, mandible, inlay graft.

The influence of initial alveolar ridge defect morphology on the outcome of implants in augmented atrophic posterior mandible: an exploratory retrospective study

OBJECTIVES

Clinicians commonly consider atrophic site topography as an important determinant in deciding the augmentation technique to utilize, as well as forecasting the likelihood of success. The purpose of this retrospective study was to examine the influence of initial atrophic posterior mandible morphology on the outcome of implants placed following augmentation.

MATERIALS AND METHODS

A total of 52 patients contributed 71 edentulous sites, and 185 implants were placed with mean follow-up of 37.97 months. The initial defect morphology was classified according to ABC classification (Journal of Oral Implantology, 37, 2013a and 361). Ridge augmentation was performed by "cortical autogenous tenting" (CAT) followed by either simultaneous or delayed implant placement after 4-6 months of healing. The European Academy of Osseointegration success criteria were used to evaluate implant outcomes.

RESULTS

The overall survival and success rates of dental implants were 98.91% and 80%, respectively. Cumulative success and survival rates in CAT group were 95% and 100% after 2 years of follow-up. The highest marginal bone loss (MBL) was observed (1.26 mm ± 0.99) around implants placed in augmented edentulous sites with initially narrow and flat alveolar crest (defect class CII). Conversely, least MBL (0.48 mm ± 0.78) was detected around implants placed into edentulous sites with two sloped boney walls (defect class AII). Differences between MBL observed around implants placed into initial defect class C, initial defect type and class A (I, II), as well as class BII, were statistically significant (P < 0.05). Among all implants, 148 were considered as successful, 26 exhibited satisfactory survival, nine with compromised survival, and two implants failed.

CONCLUSION

The present data confirmed the effect of initial ridge morphology on the outcome of implants placed into augmented bone. Specifically, class A and class B atrophic ridge defects, with one and two vertical boney walls, respectively, may be considered as more favorable recipient sites than class C defects with flat morphology. This conclusion is based on least MBL around implants placed into initial defect class A and class B augmented sites, and higher MBL in implants placed into class C recipient sites. A randomized controlled trial is warranted to examine these exploratory observations.

Coronal Split Corpus Osteotomy of the Mandible: A Modified Visor Osteotomy Technique for Bone Volume Enhancement

The bony augmentation of severely atrophied mandible is generally required for the purposes of prosthetic rehabilitations. The treatment strategies have been well defined in the literature ranging from osteotomy techniques to distraction osteogenesis. Visor osteotomy is the milestone of the reconstructive surgery for the atrophied mandible which has received some modifications. In the present study, the authors describe a new modification of visor osteotomy in which a complete coronal split osteotomy down to the inferior border at the mental region has been performed. The main advantage of this modification is to preserve the lingual cortex from the inferior border of the mandible up to the alveolar region without disturbance of the suprahyoid muscle attachments. The procedure is thought to be a "highly sensitive" one and undesired fractures may occur during splitting of the bony segments.

Vertical augmentation of the posterior atrophic mandible by interpositional grafts in a split-mouth design: a human tomography evaluation pilot study

OBJECTIVE

Using computed tomography, to compare vertical and volumetric bone augmentation after interposition grafting with bovine bone mineral matrix (GEISTLICH BIO-OSS^® ) or hydroxyapatite/tricalcium phosphate (STRAUMANN^® BONECERAMIC) for atrophic posterior mandible reconstruction through segmental osteotomy.

MATERIAL AND METHODS

Seven patients received interposition grafts in the posterior mandible for implant rehabilitation. The computed tomography cone beam images were analysed with OsiriX Imaging Software 6.5 (Pixmeo Geneva, Switzerland) in the pre-surgical period (T0), at 15 days post-surgery (T1) and at 180 days post-surgery (T2). The tomographic analysis was performed by a single trained and calibrated radiologist. Descriptive statistics and nonparametric methods were used to analyse the data.

RESULTS

There was a significant difference in vertical and volume augmentation with both biomaterials using the technique (P < 0.05). There were no significant differences (P > 0.05) in volume change of the graft, bone volume augmentation, or augmentation of the maximum linear vertical distance between the two analysed biomaterials.

CONCLUSIONS

The GEISTLICH BIO-OSS^® and STRAUMANN^® BONECERAMIC interposition grafts exhibited similar and sufficient dimensional stability and volume gain for short implants in the atrophic posterior mandible.

Simple bone augmentation for alveolar ridge defects

Dental implant procedures, both surgical placement and preimplant bone augmentation, have become an integral aspect of the oral and maxillofacial surgeon's practice. The number of dental implants placed each year continues to increase as a result of increasing patient exposure and awareness of dental implants, the increased functional and esthetic dental demands of general practitioners and patients, the overall increase in age of the US patient population, and expanded insurance coverage of dental implant-related procedures. This article outlines relevant surgical procedures aimed toward reconstructing alveolar ridge defects to restore intra-arch alveolar discrepancies before restoration-driven dental implant placement.

Long term follow-up in inferior alveolar nerve transposition: our experience

Introduction. Inferior alveolar nerve transposition (IANT) is a surgical technique used in implantoprosthetic rehabilitation of the atrophic lower jaw which has not been well embraced because of the high risk of damage to the inferior alveolar nerve (IAN). There are cases in which this method is essential to obtain good morphologic and functional rebalancing of the jaw. In this paper, the authors present their experience with IANT, analyzing the various situations in which IANT is the only surgical preprosthetic option. Methods. Between 2003 and 2011, 35 patients underwent surgical IANT at our center. Thermal and physical sensitivity were evaluated in each patient during follow-up. The follow-up ranged from 14 to 101 months. Results and Conclusion. Based on our experience, absolute indications of IANT are as follows: (1) class IV, V, or VI of Cawood and Howell with extrusion of the antagonist tooth and reduced prosthetic free space; (2) class V or VI of Cawood and Howell with presence of interforaminal teeth; (3) class V or VI of Cawood and Howell if patient desires fast implantoprosthetic rehabilitation with predictable outcomes; (4) class VI of Cawood and Howell when mandibular height increase with inlay grafts is advisable.

[Pre-implantation bone graft coffering technique for posterior mandibular edentulism: between onlay grafting and regeneration]

BACKGROUND

Pre-implant placement posterior mandibular bone grafts remain a challenge for maxillofacial surgeons. We present a coffering technique we prefer using in this localization.

SURGICAL PROCEDURE

This original technique involves creating a sagittal mandibular groove in which a graft harvested from the retromolar region is wedged vertically, after being sharpened in a bone mill. Reconstruction of the alveolar region itself is achieved by filling up the space between this vestibular coffer and the residual alveolar ridge with particulate bone graft from the bone mill.

RESULTS

A hundred patients were operated with this technique by the same team from 2005 to 2010. The treatment failed for four patients at 3 post-operative months. No alteration of inferior alveolar nerve was observed.

DISCUSSION

This coffering technique seems to be fully adequate in case of a posterior mandibular atrophy with a narrow ridge and sufficient bone height. This technique has several assets. Guided bone regeneration is associated with the use of exclusively autologous bone grafts. It may be performed under local anesthesia. The donor site is close, and the regenerated bone is of good quality. Implant placement must be achieved from 4 to 6 months after graft surgery. The drawbacks of the technique are related to donor site possibilities, and to the alveolar ridge height. Morbidity is low.

Exploring CBCT-based DICOM files. A systematic review on the properties of images used to evaluate maxillofacial bone grafts

Previous studies suggests that cone beam computerized tomography (CBCT) images could provide reliable information regarding the fate of bone grafts in the maxillofacial region, but no systematic information regarding the standardization of CBCT settings and properties is available, i.e., there is a lack of information on how the images were generated, exported, and analyzed when bone grafts were evaluated. The aim of this study was to (1) do a systematic review on which type of CBCT-based DICOM images have been used for the evaluation of the fate of bone grafts in humans and (2) use a software suggested in the literature to test DICOM-based data sets, exemplifying the effect of variation in selected parameters (windowing/contrast control, plane definition, slice thickness, and number of measured slices) on the final image characteristics. The results from review identified three publications that used CBCT to evaluate maxillofacial bone grafts in humans, and in which the methodology/results comprised at least one of the expected outcomes (image acquisition protocol, image reconstruction, and image generation information). The experimental shows how the influence of information that was missing in the retrieved papers, can influence the reproducibility and the validity of image measurements. Although the use of CBCT-based images for the evaluation of bone grafts in humans has become more common, this does not reflect on a better standardization of the developed studies. Parameters regarding image acquisition and reconstruction, while important, are not addressed in the proper way in the literature, compromising the reproducibility and scientific impact of the studies.