Feasibility and needs for simultaneous or staged bone augmentation to place prosthetically guided dental implants after extraction or exfoliation of first molars due to severe periodontitis

Recent Advances in Scaffolds for Guided Bone Regeneration

The rehabilitation of alveolar bone defects of moderate to severe size is often challenging. Currently, the therapeutic approaches used include, among others, the guided bone regeneration technique combined with various bone grafts. Although these techniques are widely applied, several limitations and complications have been reported such as morbidity, suboptimal graft/membrane resorption rate, low structural integrity, and dimensional stability. Thus, the development of biomimetic scaffolds with tailor-made characteristics that can modulate cell and tissue interaction may be a promising tool. This article presents a critical consideration in scaffold's design and development while also providing information on various fabrication methods of these nanosystems. Their utilization as delivery systems will also be mentioned.

Efficacy of Alveolar Ridge Preservation in Periodontally Compromised Molar Extraction Sites: A Systematic Review and Meta-Analysis

AIM

To investigate the efficacy of alveolar ridge preservation (ARP) in periodontally compromised molar extraction sites.

METHODS

An electronic search was performed on 10th November 2023 across five databases, seeking randomised/non-randomised controlled trials (RCTs/NCTs) that included a minimum follow-up duration of four months. The RoB2 and Robins-I tools assessed the risk of bias for the included studies. Data on alveolar ridge dimensional and volumetric changes, keratinized mucosal width, and need for additional bone augmentation for implant placement were collected. Subsequently, a meta-analysis was carried out to derive the pooled estimates.

RESULTS

Six studies were incorporated in the present review, and a total of 135 molar extraction sockets in 130 subjects were included in the meta-analysis. ARP was undertaken in 68 sites, and 67 sites healed spontaneously. The follow-up time ranged from 4 to 6 months. The meta-analysis of both RCTs and NCTs showed significant differences in mid-buccal ridge width changes at 1 mm level below ridge crest with a mean difference (MD) of 3.80 (95% CI: 1.67-5.94), mid-buccal ridge height changes (MD: 2.18; 95% CI: 1.25-3.12) and volumetric changes (MD: 263.59; 95% CI: 138.44-388.74) in favour of ARP, while the certainty of evidence is graded low to very low. Moreover, ARP appeared to reduce the need for additional sinus and bone augmentation procedures at implant placement with low certainty of evidence.

CONCLUSIONS

Within the limitations of this study, alveolar ridge preservation in periodontally compromised extraction sites may, to some extent, preserve the ridge vertically and horizontally with reference to spontaneous healing. However, it could not eliminate the need for additional augmentation for implant placement. Further, longitudinal studies with large sample sizes and refined protocols are needed.

Resorbable GBR Scaffolds in Oral and Maxillofacial Tissue Engineering: Design, Fabrication, and Applications

Guided bone regeneration (GBR) is a promising technique in bone tissue engineering that aims to replace lost or injured bone using resorbable scaffolds. The promotion of osteoblast adhesion, migration, and proliferation is greatly aided by GBR materials, and surface changes are critical in imitating the natural bone structure to improve cellular responses. Moreover, the interactions between bioresponsive scaffolds, growth factors (GFs), immune cells, and stromal progenitor cells are essential in promoting bone regeneration. This literature review comprehensively discusses various aspects of resorbable scaffolds in bone tissue engineering, encompassing scaffold design, materials, fabrication techniques, and advanced manufacturing methods, including three-dimensional printing. In addition, this review explores surface modifications to replicate native bone structures and their impact on cellular responses. Moreover, the mechanisms of bone regeneration are described, providing information on how immune cells, GFs, and bioresponsive scaffolds orchestrate tissue healing. Practical applications in clinical settings are presented to underscore the importance of these principles in promoting tissue integration, healing, and regeneration. Furthermore, this literature review delves into emerging areas of metamaterials and artificial intelligence applications in tissue engineering and regenerative medicine. These interdisciplinary approaches hold immense promise for furthering bone tissue engineering and improving therapeutic outcomes, leading to enhanced patient well-being. The potential of combining material science, advanced manufacturing, and cellular biology is showcased as a pathway to advance bone tissue engineering, addressing a variety of clinical needs and challenges. By providing this comprehensive narrative, a detailed, up-to-date account of resorbable scaffolds' role in bone tissue engineering and their transformative potential is offered.

Assessment of soft and hard tissue characteristics of ridge preservation at molar extraction sites with severe periodontitis: a randomized controlled trial

Background

Changes in alveolar bone dimension after tooth extraction may affect placement of the subsequent implant, resulting in ridge deficiency that can adversely impact long-term implant stability or aesthetics. Alveolar ridge preservation (ARP) was effective in reducing the amount of ridge resorption following tooth extraction. There is sparse evidence regarding the benefit of ARP at periodontally compromised molar extraction sockets. This study will be a randomized trial to assess the soft tissue contour, radiographical, and histological changes of ARP at molar extraction sites in order to compare severe periodontitis cases with natural healing results and determine the most beneficial and least traumatic clinical treatment for such patients.

Methods

This research is designed as a two-group parallel randomized controlled trial. The total number of tooth extraction sites will be 70 after calculation with power analysis. Teeth will be randomly assigned to two groups with the test group conducting ridge preservation and the control group healing naturally. Periodontal examination, cone beam-computed tomography (CBCT) data, and stereolithographic (STL) files obtained by intraoral scanning will be collected through the follow-up period, and bone biopsy samples would be obtained during implant surgery. The primary outcomes are the vertical and horizontal change of alveolar ridge measured on CBCT images, soft tissue contour changes evaluated by superimposing the digital impressions, alterations of mucosa thickness (as measured by superimposing the CBCT data and STL files), histological features of implant sites and periodontal parameter changes. The secondary outcomes are patient-reported post-operative reaction and conditions of simultaneous bone graft or sinus lifting procedures during implantation.

Discussion

This study will provide information about hard and soft tissue dimension changes and histomorphology evaluation following ARP and natural healing in periodontally compromised molar sites, which may contribute to complement the missing information of ARP at periodontally compromised molar extraction sockets.

Trial registration

Chinese Clinical Trial Register (ChiCTR) ChiCTR2200056335. Registered on February 4, 2022, Version 1.0.

Increased local concentrations of growth factors from leucocyte- and platelet-rich fibrin do not translate into improved alveolar ridge preservation: an intraindividual mechanistic randomized controlled trial

AIMS

Leucocyte- and platelet-rich fibrin (L-PRF) has been tested for enhancing alveolar ridge preservation (ARP), but little is known about the local release profile of growth factors (GF) and the clinical equipoise related to its efficacy remains. This study compared the patterns of GF release, early soft tissue healing and alveolar ridge resorption following unassisted healing and L-PRF application in non-molar extraction sockets.

MATERIALS AND METHODS

Atraumatic tooth extraction of two hopeless teeth per patient was followed by unassisted healing or L-PRF placement to fill the socket in 18 systemically healthy, nonsmoking subjects. This intraindividual trial was powered to assess changes in horizontal alveolar ridge dimensions 1 mm below the crest of alveolar bone. GF concentrations in wound fluid were assessed with a multiplex assay at 6, 24, 72 and 168 hours. Early healing was evaluated with the wound-healing index and changes in soft tissue volumes on serial digital scans. Hard tissue changes were measured on superimposed CBCT images after 5 months of healing.

RESULTS

L-PRF resulted in higher GF concentrations in WF as compared to the control, but no differences in release patterns or time of peak were observed. No intergroup differences in early healing parameters were observed. Alveolar bone resorption was observed in both groups. No significant intergroup differences were observed in hard tissue healing 1, 3 or 5 mm apical to the original bone crest, or in ability to digitally plan a prosthetically guided implant with or without bone augmentation.

CONCLUSIONS

L-PRF increased the GF concentrations in wound fluid of extraction sockets without shifting the pattern observed in unassisted healing, while the increased delivery did not translate into clinical benefits in early wound healing or ARP. The current findings question the assumption that increased local concentrations of GF by L-PRF translate into improved clinical outcomes. Additional definitive studies are needed to establish the benefits of L-PRF in ARP. (clinicaltrials.gov NCT03985033).

[Radiography study on osteotome sinus floor elevation with placed implant simultaneously with no graft augmentation]

OBJECTIVE

To investigate the change of endo-sinus bone height and bone volume in osteotome sinus floor elevation (OSFE) without bone graft but placing implants simultaneously by using cone beam computed tomography (CBCT) and three dimensional analysis, and to find the impacting factors on endo-sinus bone augmentation.

METHODS

OSFE was performed in 38 edentulous patients with missing teeth at posterior maxillary region, and 44 implants were placed and referred for OSFE using no graft materials. CBCT was performed pre-surgery and 9－68 months post-surgery when the patients encountered another implant surgery. The gained bone height at mesial, distal, buccal and palatal sites around the implant in sinus were measured, volumetric measurements of the endo-sinus gained bone volume (ESGBV) in the elevated region were calculated by Mimics software. Univariate analysis and multiple linear regression were performed to investigate the impacting factors on the gained bone height and ESGBV. Marginal bone loss was recorded according to the periapical radiography after implant restoration.

RESULTS

The mean residual bone height (RBH) pre-surgery was (3.41±1.23) mm, the mean protruded length (PL) into sinus of implant post-surgery was (3.41±1.28) mm, the mean endo-sinus gained bone height was (2.44±1.23) mm at distal sites, (2.88±1.20) mm at mesial sites, (2.83±1.22) mm at buccal sites and (2.96±1.16) mm at palatal sites, the mean endo-sinus gained bone height at distal sites was significantly lower than the other three sites (P < 0.05). The average endo-sinus gained bone height was (2.78±1.13) mm. The mean ESGBV was (122.15± 73.27) mm³. Univariate analysis showed the more RBH, the less bone height gained in sinus, which existed at buccal, lingual, mesial and distal sites (P < 0.001), and the more RBH, the smaller ESGBV gained (P=0.012). The ESGBV was significantly higher in the subjects whose bone generation period was more than 24 months than those whose bone generation period less than 24 months (P=0.034). The more PL, the more bone height and ESGBV gained (P=0.008). Multivariate analysis showed after adjusting factors of gender, age, smoking, width of sinus floor, thickness of sinus membrane pre-surgery, diameter and length of the implant, PL and bone generation period was positively correlated with mean endo-sinus gained bone height and ESGBV, while RBH negatively correlated with mean endo-sinus gained bone height. During the follow-up, the mean marginal bone loss was 0 (0－1.41) mm and all the implants loaded successfully.

CONCLUSION

OSFE without bone graft but with placed implant simultaneously can increase endo-sinus gained bone height and ESGBV. RBH, PL and bone generation period are the significant factors impacting endo-sinus bone augmentation.