Reconstruction of the severely resorbed (Class VI) jaws: routine or exception?

[Comparative experiments of stripping sheep maxillary sinus mucosal with new-type stripper and umbrella detacher]

OBJECTIVE

To compare the stripping length obtained through the model of 0.012 and 0.014 of the nickel-titanium dual-stage maxillary sinus mucosa stripper, and the umbrella detacher.

METHODS

Twenty-four goats (1.5-2 years old) were chosen, randomly divided into A, B, C groups, each group of eight. Group A was 0.012 model group, group B was 0.014 model group, group C was umbrella detacher group. Animal model was established, and maxillary sinus mucosa was stripped to the left and right sides of the bottom of the sinus in three groups. The data was measured when stripping to the limit or being perforated.

RESULTS

The average length of group A was 12.41 mm±4.35 mm, two cases perforated. The average length of group B was 23.38 mm±4.84 mm, one case perforated. The average length of group C was 2.61 mm±0.30 mm. The population mean of stripping length in three groups was not all the same calculated by analysis of variance (P<0.01). There were significant differences in the stripping length of the three groups by the SNK test (P<0.05).

CONCLUSIONS

The nickel-titanium dual-stage maxillary sinus mucosa stripper can achieve a larger mucosal stripping range. The stripper with a model of 0.014 has a moderate flexibility and safety, and it can strip a large area of sinus mucosa.
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Retrospective evaluation of 211 patients with maxillofacial reconstruction using parietal bone graft for implants insertion

PURPOSE

For a century, autologous bone grafts have been used in maxillofacial reconstruction. The ideal bone harvest site and grafting procedure remains a point of contention in regards to obtaining optimal long-term results with sufficient bone quantity and density without serious complications. More recently, confronted with growing patient requests and biomaterials development, maxillofacial surgeons and dentists have been considering these issues as they relate to pre-implant surgery. This study sought to evaluate implant success rate and complications following pre-implant surgery with parietal bone grafting.

MATERIALS AND METHODS

A retrospective study was carried out on patients who underwent maxillofacial reconstruction of different sites (symphysis, mandibular corpus, maxillary sinus and premaxilla) for the purpose of implant insertion.

RESULTS

311 procedures in 211 patients were included. The implant osseointegration rate was around 95%. Clinical follow-up ranged from 10 months to 11 years. A secondary procedure was performed in 6.1% of cases and we noted no serious complications at the harvest site.

DISCUSSION

With good revascularization and osseointegration of the graft, the use of parietal bone leads to an implant success rate similar to that seen in the literature. Moreover, the use of this material results in few infections and low bone resorption provided there is strict immobilization of the graft and no tension on the soft tissue sutures.

CONCLUSION

Parietal bone grafts technique possess the required qualities for the success of implant surgery, offering results at least as interesting as others using autogenous bone and with no serious complications on donor site.

Alveolar ridge augmentation using distraction osteogenesis: a clinical trial

BACKGROUND

Severely resorbed ridges present a great challenge to prosthodontic rehabilitation. Available reconstructive options include autologous/alloplastic augmentation with questionable results, or regeneration of new bone under gradual and controlled tension using distraction osteogenesis. This study focused on use of distraction osteogenesis for the treatment of vertically deficient alveolar ridges to assess its feasibility and outcome.

MATERIALS AND METHODS

Alveolar distraction osteogenesis (ADO) was studied at 10 different intra-oral, partial or complete edentulous sites. After a latency period of 5 days, distraction was carried out for 6-7 days at the rate of 0.5 mm every 12 hours (1 mm/day). Distractor was removed after a consolidation period of 12 weeks.

RESULTS

The mean height gained at the 10 intra-oral sites was 4.8 mm with standard deviation of ± 0.056. The mean follow-up period was 2 years. Complications of therapy included hardware failure, wound gape and extra-oral scar. The overall complication rate was 10%.

CONCLUSION

Distraction osteogenesis is a promising option to aid uneventful prosthodontic rehabilitation of severe vertically resorbed alveolar ridges.

Maxillary autogenous bone grafting

Reconstruction of the atrophic maxilla for dental implant placement has many unique considerations. There are several methods available to augment the atrophic maxilla. Of these, autogenous bone grafting offers a well-proven predictable method for ridge augmentation and defect repair for dental implant placement. There are several advantages of using autogenous bone grafts. This article primarily focuses on the use of autogenous onlay bone grafts to reconstruct the atrophic maxilla.

Indirect sinus floor elevation for osseointegrated prostheses. A 10-year prospective study

The aim of this study was to evaluate the indirect/closed maxillary floor elevation technique for the insertion of osseointegrated implants to support fixed prostheses clinically. Thirty-one patients (19 female, 12 male) with a mean age of 62 +/- 9 years were selected for this study. All patients needed implants in the posterior maxillary region to support osseointegrated prosthesis. Forty-seven implants were inserted using the indirect/closed sinus floor elevation method, and another 31 implants were placed in the same individuals as intra-individual control. No augmentation material was used along with implantation. The mean bone height before sinus lift was 9.78 +/- 1.68 mm (minimum 5.6 mm), and for controls it was 15.62 +/- 3.44 mm. The average length of the implants used was 12.00 +/- 1.70 mm, whereas for controls it was 13.39 +/- 1.60 mm. The patients were recalled for periodic checkups every 6 months, and the radiographic controls were made every 12 months. One control fixture failed after uncovering; 77 implants were loaded, and 5 of them failed (2 controls and 3 of the sinus lift group) between 3 and 59 months following loading. One hundred nineteen months after surgery (112 months following loading), the censored survival rate (Kaplan-Meier) was 93.6% for sinus lift implants and 90.3% for controls. The crestal bone level changes were not significant either before loading or after loading for both sinus lift and control implants. None of the remaining implants showed any signs of mobility or peri-implant disease, and none of the patients exhibited sinus problems during the entire observation period.

A new technique for the transcrestal sinus floor elevation and alveolar ridge augmentation with press-fit bone cylinders: a technical note

BACKGROUND

The minimally invasive sinus floor elevation as first described by Summers is limited in the volume of augmentation that is possible. In contrast, the more invasive approach is the sinuslift of Tatum which is indicated for greater bone deficiencies. Therefore, a new technique was developed for transcrestal elevation of the sinus floor and alveolar ridge augmentation with bone dowels in press-fit technique.

MATERIALS & METHODS

The crestal cortical bone is cut with a hollow grinder followed by an indirect sinus floor elevation with a plunger. The cylindrical defect is then filled with a cylindrical bone transplant with the press-fit technique.

RESULTS

The method was tested in ten fresh porcine skulls and was successful when applied subsequently in two fresh human cadavers (both female, age 60 and 92 years). This was followed by the insertion of another cylinder in overlapping mosaic manner with the dowel-lift technique in the left maxilla in one cadaver. A sinoscopy of the second cadaver experiment showed no perforation of the maxillary sinus membrane. The result was convincing.

CONCLUSION

A new method for transcrestal elevation of the maxillary sinus floor and alveolar ridge augmentation with bone cylinders in press-fit technique was developed. The operation combines the minimally invasive approach of Summers with a large augmentation volume otherwise requiring the direct technique of Tatum. These results should encourage further preclinical experiments.

Lateral femoral cutaneous nerve and iliac crest bone grafts—anatomical and clinical considerations

This study investigates the topographical relationship of the lateral femoral cutaneous nerve (LFCN) to the anterior iliac crest and its clinical relevance in the context of bone graft harvesting. In the anatomical part of the study, LFCN was dissected and its course investigated in 34 human formalin-embalmed cadavers. In the clinical part, data of patients who underwent an iliac crest bone grafting procedure were collected and analysed. The obtained results were then compared with the results of other investigators published in the medical literature. From 34 nerves, the lateral branch of 1 LFCN (2.9%) crossed the anterosuperior iliac spine (ASIS) prominence at a distance less than 5mm superolaterally from the most anterior point of the spine. All other nerves ran below the inguinal ligament with an average distance of 14.6mm in the inferomedial direction from the spine. In 4 out of 298 patients (1.3%) who underwent harvesting of monocortical bone grafts from the inner table of the ilium, sensory disturbances in the dermatome of LFCN were observed. After a maximum period of 12 months all sensory disturbances resolved so that no case of permanent sensory impairment was recorded. The relatively low incidences of iatrogenic LFCN damage can be attributed to a standardized surgical concept which employs a lateral incision and layer by layer dissection to the periosteum/iliacal fascia level in order to identify the nerves potentially crossing the iliac crest above the ASIS.

Changes in the volume and density of calvarial split bone grafts after alveolar ridge augmentation

OBJECTIVES

One main problem occurring after bone grafting is resorption, leading to insufficient bone volume and quality, and may subsequently cause dental implant failure. Comparison of graft volume and bone density of iliac crest and calvarial transplants determined by animal studies demonstrates significantly lower resorption of bone grafts harvested from the skull. This paper is the first clinical study evaluating bone volume and density changes of calvarial split bone grafts after alveolar ridge reconstruction.

MATERIAL AND METHODS

Bone volume and density were determined using CT scans and the software program Dicom Works in a total of 51 calvarial grafts after alveolar ridge augmentation in 15 patients. CT scans were taken in all 15 patients immediately after grafting (T0) and before implantation after a postoperative period of 6 months (T1). In five patients (26 calvarial grafts), a 1-year follow-up was performed (T2).

RESULTS

A mean volume reduction of 16.2% at T1 (15 patients) and 19.2% at T2 (five patients) was observed. Bone density was high--about 1000 Hounsfield units--and did not change during the 1-year period. At the time of implantation, 41 transplants were classified as quality 1 bone and 10 as quality 2-3 bone. Grafting area and the technique used for grafting (inlay or onlay graft) did not affect the postoperative bone volume reduction. Generalized osteoporosis did not increase the resorption rate of calvarial transplants.

CONCLUSION

Based on these findings, calvarial split bone grafts are a promising alternative for alveolar ridge reconstruction in dental implantology.

Reconstruction of the severely atrophic mandible using calvarial split bone grafts for implant-supported oral rehabilitation

OBJECTIVES

This article describes reconstruction of the severely atrophic mandible using calvarial bone grafts for implant-supported prosthetic oral rehabilitation. The study aim was to evaluate the efficacy of the treatment by determining implant survival and complication rates, and the extent of the postoperative graft resorption.

STUDY DESIGN

Ten patients who underwent the treatment were followed clinically and radiologically using panoramic radiographs and CT scans during a mean postoperative period of 30 months.

RESULTS

Good bone healing was observable 6 months postoperatively. The height reduction measured on panoramic radiographs was insignificant (mean 0.68 mm). Only minor complications occurred. Implant survival was 95%. Prosthodontic treatment was successfully performed in all cases, resulting in an improvement of oral function. Histological analysis of 1 bone biopsy showed minimal resorptive changes in otherwise very dense bone.

CONCLUSION

Augmentation using calvarial grafts is a promising treatment alternative for the severely atrophic mandible.

Distraction osteogenesis with subperiosteal devices in edentulous mandibles

Nine patients with severely atrophic edentulous mandibles were treated by distraction osteogenesis with subperiosteal distractors for vertical augmentation of the anterior alveolar bone before insertion of implants. All the patients had severe complications and we conclude that the use of subperiosteal devices for vertical augmentation of edentulous mandibles is hazardous and offers no advantage over other surgical methods.

Kombination der Sinusliftoperation mit der lateralen Kieferkammaugmentation

PURPOSE

This paper describes a surgical and prosthetic procedure for treating the extremely atrophic maxilla. It explains a two-staged surgical technique, donor and recipient site morbidity, implant survival, and the implant-retained prosthetic rehabilitation of the patients.

PATIENTS AND METHODS

A total of 57 consecutive patients were treated with a sinus lifting procedure and a simultaneous lateral augmentation using autogenous corticocancellous block and particulate bone grafts from the iliac crest. After a 6-month bone healing period, a total of 284 endosteal Titanium screw implants were inserted. Following a 3-month osseointegration period, the implants were exposed and loaded with either fixed or removable prostheses.

RESULTS

In three cases a partial bone graft loss was observed; however, enosseous implantation was possible as planned. During the observation period none of the 284 implants was lost; 3 implants exhibited treatable peri-implant infection. Complications at the donor and recipient sites were minimal and did not negatively influence the overall clinical result of the treatment.

CONCLUSION

The combination of sinus lift procedure and lateral augmentation for the treatment of the extremely atrophied maxilla proved to be a safe method that produces good and reliable clinical results.

Surgical reconstruction of maxilla and midface: Clinical outcome and factors relating to postoperative complications

AIM

The aim of this study was to evaluate the success rate of different techniques of repairing maxillary and midfacial defects according to their extent.

PATIENTS AND METHODS

In this retrospective study, 47 maxillary reconstructions in 41 patients were reviewed. Evaluation took place an average of 4.5 years postoperatively. The cases were divided into three groups according to the classification of Brown et al. (Br J Oral Maxillofac Surg 40: 183-190, 2002): Group 1: maxillary defects limited to one side (Class 2a); Group 2: bimaxillary defects (Classes 2b and 2c); Group 3: maxillary/midfacial defects (Classes 3 and 4). Most reconstructions were performed with non-vascularized bone grafts in the first patient group, whilst microvascular soft tissue flaps combined with free bone grafts were used in the second group, and re-vascularized osteocutaneous flaps in the third group.

RESULTS

Overall flap survival was 79%. Dental reconstruction was successfully completed in 31 cases (66%). Postoperative infection leading to transplant loss was the main reason for failure. This complication was specifically associated with temporal osteomuscular flaps (50%) and free iliac crest grafts (61%) and was related to the extent of the defect. In the reconstructive methods evaluated here, associated radiotherapy had a minor influence on the occurrence of complications.

CONCLUSION

Non-vascularized iliac bone grafts should be used sparingly in Class 2b, even in combination with microvascular flaps. There is a very limited indication for these grafts in Classes 3 and 4. Temporal osteomuscular flaps do not seem to be suitable for maxillary reconstruction.

Alveolar Ridge Augmentation: A Comparative Longitudinal Study Between Calvaria and Iliac Crest Bone Grafts

Insertion of endosseous implants is often difficult because of lack of supporting bone. In the case of severe atrophy of the jaws, a large volume of autogenous bone can be harvested from the iliac crest and calvaria. Both grafts undergo partial resorption with time, but the rate of bone loss has not been fully elucidated. The aim of this study was to evaluate the alveolar bone height gain (ABHG) obtained with iliac crest and calvaria bone grafts. Twenty-five patients had mandibular bone grafts, 32 had maxillary bone grafts, and 11 had both mandibular and maxillary bone grafts. Measures were made on preoperative, postoperative, and follow-up radiographs. A general linear model was used to evaluate the rate of ABHG plotted against months elapsed from the time of the operation to the time of follow-up. General linear model output showed a statistically significant effect for only the type of donor bone graft (P = .004), with a better ABHG for calvaria. The iliac crest bone grafts lost most of the ABHG in the first 6 months, whereas calvaria bone grafts lost ABHG over a greater interval of time. The type of bone graft is the strongest predictor of ABHG, and calvaria bone graft had a higher stability than did iliac bone graft. However, the gap in ABHG between the 2 grafts tended to decrease over time.

Extensive augmentation of the alveolar ridge using autogenous calvarial split bone grafts for dental rehabilitation

Free autogenous iliac bone is the most commonly used graft material for an extensive alveolar ridge reconstruction. The application of iliac bone, however, is associated with problems, such as transplant loss resulting from postoperative infection and late bone resorption. A bone-graft material more suitable than iliac bone is therefore still needed. This paper describes a concept for alveolar-ridge reconstruction using calvarial split bone, and the related surgical techniques. Clinical and radiological follow-up examinations were undertaken to evaluate the potential benefit of calvarial split bone in alveolar-ridge reconstruction. Between 1999 and 2002, 13 patients with a mean age of 54 years (range 31-70 years) underwent surgery, seven patients in the maxilla and six in the mandible. In four cases, wound dehiscence occurred postoperatively. In one of these cases, the dehiscence was associated with a local infection. However, no bone transplants were lost. After a mean follow-up time of 19.6 months, bone resorption, measured radiologically, was minimal. Endosseous dental implants were successfully installed and maintained. Satisfactory prosthetic rehabilitation was achieved in all patients. Our preliminary experience suggests that calvarial split bone may be regarded as a promising alternative to autogenous iliac bone in connection with extensive augmentation of the alveolar ridge.

Tissue response to poly-L-lactide acid-polyglycolic acid absorbable screws in autogenous bone grafts: a histologic morphological analysis

OBJECTIVES

To evaluate the local bone condition of autogenous chin grafts in contact with resorbable polymers fixation devices.

MATERIAL AND METHODS

Seven patients presenting severe maxillary and mandibular atrophy underwent alveolar ridge reconstruction with autogenous chin grafts fixed with conventional metallic screws, who received poly L-lactide acid-polyglycolic acid and titanium test screws for histological evaluation after 4 months of implantation.

RESULTS

Viable bone tissue could be seen in the specimens related to titanium test screws, with no signs of bone resorption or inflammation. A thick layer of fibrous connective tissue was observed between the resorbable test screws and bone tissue, which presented a few areas of resorption.

CONCLUSION

There are no contraindications of both materials for use as fixation devices in autogenous bone grafts. However, care must be taken when using absorbable screws in a period of 4 months, which can interfere with the sequence of the treatment with endosseous dental implants.

Simultaneous bimaxillary alveolar ridge augmentation by a single free fibular transfer: a case report

Class VI atrophy according to Cawood still represents a major challenge in pre-prosthetic surgery. Reconstruction of mandibular and maxillary bony defects using microvascular techniques is safe and reliable. The fibula, due to its morphological properties, is ideal for alveolar ridge augmentation and its donor site morbidity is the lowest among vascularized bone flaps. In this paper, we report the first case, to our knowledge, of extreme atrophy of both jaws, successfully treated by simultaneous bony augmentation of the maxillary and mandibular alveolar ridges with just one free fibula flap. Pre-operative planning, surgical technique and prosthetic restoration are discussed in detail.

Treatment of severe atrophy of the maxilla with the prefabricated free vascularized fibula flap

Treatment of severe maxillary atrophy despite complex major surgery often ends up with an unsatisfactory result. This paper presents the augmentation of the maxilla with a prefabricated free vascularized fibula flap in combination with ITI implants (Straumann AG, Waldenburg, Switzerland) in 4 patients. The technique of prefabrication for the reconstruction of maxillofacial defects is described based on the experience with 17 patients. The key points of this treatment are i) preoperative planning and fabrication of the drilling template; ii) prefabrication of the fibula with ITI implants and performing of a 'vestibuloplasty" using a skin graft; iii) technical construction and fabrication of the suprastructure and the denture; iv) reconstruction of the maxilla using the prefabricated fibula as free vascularized flap. The reconstructions with the fibula flaps were successful and the 18 ITI implants that have been inserted showed good osseointegration without loss of attachment in all 4 patients after a mean observation period of 12 months.