Bone graft healing in reconstruction of maxillary atrophy

Alveolar bone remodeling in virtually planned, bone-grafted vs non-grafted guided flapless implant surgery in the anterior maxilla: a cross-sectional retrospective follow-up study

PURPOSE

In patients who underwent virtual planning and guided flapless implant surgery for teeth missing in the anterior maxilla, we compared buccal bone loss between those treated with and without autogenous bone augmentation.

METHODS

Of 22 patients with teeth missing because of trauma or aplasia, 10 (18 implant sites) were reconstructed with buccally placed bone graft harvested from the mandibular ramus, and 12 were non-reconstructed (16 sites). Baseline cone-beam computed tomography allowed for implant planning using the NobelClinician® software and was performed again at 1 year after functional loading. The marginal bone level was assessed radiographically at post-implant baseline and at follow-up.

RESULTS

At follow-up, buccal bone loss differed significantly between groups at the central level of the implant (p = 0.0005) but not at the coronal level (p = 0.329). The mean marginal bone level change was 0.6 mm, with no significant between-group difference (p = 0.876). The actual implant position often deviated in the vertical or sagittal plane by an average of 0.3-0.6 mm from the planned position.

CONCLUSION

Compared with non-reconstructed patients, reconstructed patients experienced significantly more buccal bone loss at the central level of implants. The groups did not differ at the coronal level or in marginal bone loss, possibly because of the more augmented bone at the central level among reconstructed patients. Differences between planned versus actual implant positions should be considered in situations of limited bone volume at the planned implant site.

Modified Le Fort I interpositional grafting of the severe atrophied maxilla - a retrospective study of 106 patients over 10 years

OBJECTIVES

The objective of this study was to evaluate a modified Le Fort I interpositional grafting followed by dental implants for the rehabilitation of edentulous atrophied maxillae (Cawood classes IV and V). The surgical modification was a bilateral sinus floor augmentation prior to the osteotomy. This generated a closed recipient bed which allowed the use of particulated bone grafts (xenogenic bone mineral) and a reduced amount of autologous iliac bone grafts.

MATERIALS AND METHODS

106 patients with maxillary interpositional bone grafts were included in this retrospective analysis between 2006 and 2020. The panoramic radiographs and lateral cephalograms were analysed to assess the gain and stability of the maxillary bone and the peri-implant bone loss. In addition, the observational period of up to 14 years implant survival and success was evaluated.

RESULTS

A stable vertical bone height with mean 0.63 ± 1.41mm resorption over 5 years after implant loading was observed. A mean of 0.20 ± 0.37mm marginal bone loss was noted after 5 years. The implant survival was 96.4% after 5 years and implant success can be rated 91.7% in a mean follow-up period of 93 months and 168 months maximal observation time. Perioperative complications included sinus membrane perforation (59.43%), wound healing disturbances (25.47%) and transient primary complications (13.78%). All receded apart from two subtotal graft losses (1.8%).

CONCLUSIONS

The modified Le Fort I osteotomy with interpositional bone grafts is a predictable procedure in terms of bone and implant stability. Patients with atrophic maxillae who are fit for surgery should be informed about risks and benefits of this treatment alternative.

Evaluation of the surgical and prosthetic success of All-on-4 restorations: a retrospective cohort study of provisional vs. definitive immediate restorations

Background

All-on-4 concept allows an immediate restoration, which is frequently a provisional restoration (PR), and will be replaced by a definitive restoration (DR) a few months later. However, this approach involves much higher treatment efforts and costs, compared to a DR immediately after implantation. PRs were mostly incorporated in the introductory phase of the All-on-4 concept in our respective clinics. Today, PRs are only used for referred patients and bimaxillary restorations. The aim of the study was to investigate whether PRs and DRs have comparable success rates.

Methods

A total of 126 patients with 136 All-on-4 restorations supported by 544 implants were included in this retrospective cohort study. The observation period was 1 year. In 42 cases, a PR was placed initially and replaced by a DR 3 months later. In 94 cases, a DR was placed immediately. Biological, technical, and severe (loss of an implant or PR/DR) complications associated with PRs and DRs were compared. The absence of a serious complication was considered a success.

Results

A total of 27 patients were affected by 33 complications, 19 biological (2 PR and 17 DR) and 14 technical (6 in PR and 8 in DR) in the first 3 months. Eight patients had ten severe complications (1 PR and 9 DR). Severe complications were all implant losses. Implant survival rate was 98.2% (99.4% PR and 97.6 DR), and restoration survival rate was 94.4% (97.6% PR and 92.6% DR). Six out of the ten implant losses occurred in the posterior maxillae of male patients. After 3 months, ten complications occurred in six patients within 1 year. One of these complications was an implant loss in the posterior maxillae of a male patient.

Conclusion

PRs and DRs showed comparable complication rates during the observation period. Only in male patients did implant losses occur more frequently in the posterior maxilla.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-021-00330-1.

Resorption of retromolar bone grafts after alveolar ridge augmentation-volumetric changes after 12 months assessed by CBCT analysis

In this pilot study, a volumetric analysis of retromolar onlay bone grafts over a period of 12 months was conducted, using repeated CBCT imaging combined with automated image registration.

Eleven patients being treated with 16 bone grafts taken from the retromolar area were examined by CBCT scanning prior to bone augmentation (T0), immediately after bone augmentation (T1) and after a healing time of 12 months after augmentation (T2). Graft volumes were measured at each time point after automated image registration of consecutive CBCT scans.

The mean volume of the augmented site was 372.2 ± 179.4 mm³. Resorption relative to the original augmented volume was 43.7% ± 19.0% after 12 months.

Three-dimensional graft resorption could be precisely depicted by the use of automated image registration for CBCT data over a period of 12 months and demonstrated extensive volumetric changes of bone grafts taken from the ascending ramus of the mandible.

Graft resorption and continuous bony remodeling of the grafted site before and after implant insertion have to be carefully considered by the clinician.

Long-term evaluation of three-dimensional volumetric changes of augmented severely atrophic maxilla by anterior iliac crest bone grafting

PURPOSE

The purpose of this study was to evaluate long-term three-dimensional graft resorption following reconstruction of the severely atrophic maxilla with anterior iliac crest bone grafting.

METHODS

Twenty-two patients (13 males), who underwent autogenous bone grafting and implant placement to their severely atrophic maxillary alveolar ridges were identified and included in the study. Pre- and postoperative cone-beam computed tomography (CBCT) scans of 40 recipient grafting sites were evaluated to calculate volumetric changes over time. CBCT scans were performed preoperatively (V0) and one week (V1), three months (V2), one year (V3), and three years (V4) following the augmentation operation.

RESULTS

The average graft resorption from V1 to V2, V1 to V3, and V1 to V4 was 31.42%, 33.96%, and 37.96%, respectively. Initial graft volume reduction within the first three months was statistically higher compared to other postoperative periods (P<0.013). The rate of resorption reduced slightly from the third month of the surgery (V2) (P>0.013). There was no statistical difference between resorption volume and gender, type of prosthesis, the presence of vestibuloplasty, or patient age (P>0.05).

CONCLUSION

The overall success rate of the iliac bone block grafts was found to be high. The volumetric resorption rates associated with the graft were favourable for the reconstruction of the maxilla and for permitting the placement of dental implants three months after augmentation. The highest graft resorption was found at the third postoperative month. Placement and loading of the implants reduced the resorption rate slightly over time.

[Recent research advances on alveolar ridge preservation after tooth extraction]

Resorption of alveolar bone that occurs following tooth extraction is irreversible, it may compromise the restoration of implants or conventional prostheses. Ridge preservation can minimize ridge resorption after tooth extraction. In this article, healing features of socket after tooth extraction, factors influencing ridge remodeling, and the use of bioma-terials were reviewed.

Bone grafting for alveolar ridge reconstruction. Review of 166 cases

Objective:

to investigate the predictive factors of failure in bone grafts for alveolar ridge augmentation and implant surgery.

Methods:

we reviewed the charts of 166 patients operated between 1995 and 2014. A total of 248 grafting procedures were performed. We submitted the data to the binomial test at 5% significance.

Results:

grafts to gain width of the alveolar ridge (65.32%) were more frequent than sinus lifting (p<0.0001) and the number of grafts to the posterior maxilla (48.8%) was greater than in other regions (p<0.01); 6.04% of the grafts were lost. The losses in anterior (p<0.0309) and posterior (p<0.0132) maxilla were higher than in the mandible. There were 269 ​​implants installed in the grafted areas, of which only 4.83% were lost. The number of implants lost (4.51%) in areas of onlay grafts was not statistically higher than those placed after sinus lifting (2.63%, p<0.2424). Losses were greater in the anterior (53.85%) and posterior (38.46%) maxilla than in the mandible (p<0.031). Regarding patients' age, 76.92% of the lost grafts (p<0.006) and 80% of the lost implants (p<0.001) were installed in patients over 40 years.

Conclusion:

failure rate was higher both for grafts and dental implants in the maxilla and in patients over 40 years of age.

Objetivo:

investigar os fatores preditivos de falhas em enxertos ósseos para aumento do rebordo alveolar e cirurgia de implantes.

Métodos:

os prontuários de 166 pacientes, operados entre 1995 e 2014, foram revistos. Um total de 248 enxertos foi realizado. Os dados foram submetidos ao teste binomial a 5% de significância.

Resultados:

os enxertos para ganho em espessura do rebordo alveolar (65,32%) foram mais frequentes do que levantamentos de seio maxilar (p<0,0001) e o número de enxertos para a região posterior da maxila (48,8%) foi maior do que em outras regiões (p<0,01). Foram perdidos 6,04% dos enxertos. As perdas em maxila anterior (p<0,0132) e posterior (p<0,0309) foram maiores do que na mandíbula. Foram instalados 269 implantes nas áreas enxertadas e apenas 4,83% perdidos. O número de implantes perdidos (4,51%) em áreas de enxertos em bloco não foi estatisticamente maior do que na área de seios maxilares enxertados (2,63%) (p<0,2424). As perdas foram maiores na região anterior (53,85%) e posterior (38,46%) da maxila em relação a mandíbula (p<0,031) e, 76,92% dos enxertos (p<0,006) e 80% dos implantes perdidos (p<0,001), foram instalados em pacientes com mais de 40 anos de idade.

Conclusão:

maior taxa de falhas foi observada para enxertos e implantes dentários realizados em maxila e em pacientes com mais de 40 anos de idade.

Block iliac bone grafting enhances osseous healing of alveolar reconstruction in older cleft patients: A radiological and histological evaluation

Background

Older alveolar cleft patients (&12 years old) often have wide bone defect as well as teeth loss, resulting in poor osseous healing with conventional alveolar bone grafting (ABG). In this study, we investigated a surgical technique of block iliac bone grafting for the alveolar cleft reconstruction and evaluated the clinical and radiological outcomes of these cleft patients.

Material and Methods

Fifteen patients were included in this study. All cases received preoperative cone bean computed tomography (CBCT) scans for the alveolar cleft evaluation. Osseous outcomes of block iliac bone grafting were assessed at 1 week, 3- and 6-month postoperatively. Volume changes and bone resorption rates were calculated using the measurement modules of Simplant software. Bone samples from one patient undergoing dental implantation were assessed by micro-CT and histological examination. The morbidities of donor-site were analyzed by clinical examination and questionnaire survey.

Results

The average age of the case series was 18.53±2.50 years. The intraoral incision of thirteen cases healed well. However, two cases had oronasal fistula and graft exposure at 1-week postoperatively. The results of follow-up CBCT scans showed significant resistance to radiation on both sides of the bone graft, suggesting a good osseous healing and new bone formation. The mean residual bone volume was 1.68±0.26 cm3, 1.29±0.23 cm3 and 1.15±0.23 cm3 at 1-week, 3- and 6-month postoperatively. Correspondingly, the mean bone resorption rates in 3- and 6-month postoperative were 21.78±6.88% and 30.66±8.97%, respectively. From micro-CT and HE examinations, the block bone samples exhibited a cancellous structure in which mature bone trabecula and functional blood vessels appeared. The average scores of donor-site morbidities were drastically decreased at 3- and 6-month postoperatively compared with those at 1-week postoperatively.

Conclusions

Our results demonstrated that block iliac bone grafting could achieve satisfying osseous outcomes in older alveolar cleft patients, and this technique provided favorable bony condition for further treatments, especially dental implantation.

Key words:Alveolar bone grafting, Block bone grafting, Osseous healing, CBCT.

Healing at the Interface Between Autologous Block Bone Grafts and Recipient Sites Using n-Butyl-2-Cyanoacrylate Adhesive as Fixation: Histomorphometric Study in Rabbits

The aim of the present split-mouth (split-plot) study was to describe the sequential healing in the interface between autologous bone grafts and recipient parent bone, fixed using an n-butyl-2-cyanoacrylate adhesive with or without an additional titanium fixation screw. Bone grafts were collected from the calvaria and fixed to the lateral aspect of the mandible in 24 rabbits. The cortical layers of the recipient sites were perforated, and the grafts were randomly fixed using an n-butyl-2-cyanocrylate adhesive, either alone or in conjunction with a 1.5 mm × 6.0 mm titanium fixation screw. The animals were sacrificed after 3, 7, 20, and 40 days, and histomorphometric evaluations of the interface between graft and parent bone were performed. Only 2 of 6 grafts in each group were partially incorporated to the parent bone after 40 days of healing. The remaining grafts were separated from the parent bone by adhesive and connective tissue. It was concluded that the use of n-butyl-2-cyanoacrylate as fixation of an autologous bone graft to the lateral aspect of the mandible was able to maintain the fixation over time but did not incorporate the graft to the recipient sites. Use of fixation screws did not improve the healing.

Lateral ridge augmentation with Bio-Oss alone or Bio-Oss mixed with particulate autogenous bone graft: a systematic review

The objective of this systematic review was to test the hypothesis of no difference in implant treatment outcomes when using Bio-Oss alone or Bio-Oss mixed with particulate autogenous bone grafts for lateral ridge augmentation. A search of the MEDLINE, Cochrane Library, and Embase databases in combination with a hand-search of relevant journals was conducted. Human studies published in English from 1 January 1990 to 1 May 2016 were included. The search provided 337 titles and six studies fulfilled the inclusion criteria. Considerable variation prevented a meta-analysis from being performed. The two treatment modalities have never been compared within the same study. Non-comparative studies demonstrated a 3-year implant survival of 96% with 50% Bio-Oss mixed with 50% autogenous bone graft. Moreover, Bio-Oss alone or Bio-Oss mixed with autogenous bone graft seems to increase the amount of newly formed bone as well as the width of the alveolar process. Within the limitations of this systematic review, lateral ridge augmentation with Bio-Oss alone or in combination with autogenous bone graft seems to induce newly formed bone and increase the width of the alveolar process, with high short-term implant survival. However, long-term studies comparing the two treatment modalities are needed before final conclusions can be drawn.

Reconstruction of the severely atrophic edentulous maxillae with calvarial bone grafts

OBJECTIVES

Treatment of the severely atrophic maxilla with dental implants is challenging due to the insufficient horizontal and vertical bone volume and centripetal resorption pattern of the maxilla. Bone-augmentation procedures are often necessary prior to implant placement. The objective of this study was to assess the suitability of using calvarial bone grafts to enable implant placement in severely atrophic maxillae.

MATERIAL AND METHODS

Seventeen patients with severe atrophic edentulous maxillae were reconstructed with autogenous calvarial bone grafts. After a 4-month healing period, the patients received a total of 134 dental implants, which were left to heal in submerged positions for 3 months before prosthetic rehabilitation was performed. Patients were followed clinically and radiographically for an average observation period of 53.94 months.

RESULTS

At the intraoral recipient sites, two infections developed, causing partial loss of the respective bone grafts. Implant placement, however, was possible at all sites. No donor-site complications occurred. Two of 134 implants were lost in two patients prior to prosthetic loading. The implant survival rate was 98.51%. The implant success rate was 87.6%, and a mean marginal bone loss of 0.62 mm (SD 0.77 mm) was documented.

CONCLUSIONS

Patients with severe bone atrophy of the edentulous maxilla can be successfully reconstructed with calvarial bone grafts and dental implants and show a stable clinical and radiographic situation after a mean observation period of 53 months.

Prospective tomographic evaluation of autogenous bone resorption harvested from mandibular ramus in atrophic maxilla

Autogenous bone is considered the criterion standard for grafting procedures of severely resorbed alveolar ridges. However, the rate of autogenous graft resorption remains controversial. The aim of this study was to evaluate the mandibular graft resorption with cone beam computed tomography after 10 and 180 days of augmentation procedures in the atrophic maxilla. Twenty-two patients received 36 autogenous bone grafts harvested from the mandibular ramus. Tomographical evaluations were carried out after 10 (T1) and 180 (T2) days of augmentation procedures to obtain bone grafts area measurements. After 10 days postoperatively (T1), the mean area of bone graft was 81.38 mm (range, 46.33-113.73 mm), whereas, after 180 days postoperatively (T2), the mean area of bone graft was 66.13 mm (range, 33.51-101.93 mm). The mean percentage variation of graft resorption between T1 and T2 was 18.38%. Autogenous bone blocks harvested from the mandibular ramus presented a reduction of 18.38% in the measurement areas after the augmentation procedures in the atrophic maxilla. Therefore, the use of autogenous bone blocks remains as a viable and predictable procedure for the rehabilitation of the atrophic maxillae. Thus, other studies must be carried out to improve the knowledge on the bone graft resorption, which may serve as a basis for the development of more effective strategies for the rehabilitation of patients with an atrophic maxilla.