A Pilot Investigation Generating an Alternative Therapeutic Strategy Combining Deproteinized Bovine Bone and Gelatin Sponge for a Novel Implant Material in Sinus Floor Elevation Operation.

BACKGROUND Implant placement in the posterior maxilla is typically complicated by a shortage of bone. Gelatin sponge could be combined with an appropriate material to enhance mechanical strength and maintain stability of an implant. This study aimed to evaluate the clinical application of bone grafting with bovine bone mixed with gelatin sponge. MATERIAL AND METHODS Fifty-four patients were divided into a control group (deproteinized bovine bone, n=26) and a test group (deproteinized bovine bone combined with gelatin sponge, n=28). Implants were placed in patients simultaneously after surgery (operation). Cone-beam computed tomography examination was carried out immediately and 6 months after surgery. Space with grafting materials was measured with Mimics software (version 16.0). RESULTS No remarkable differences were found for simultaneous placement, height of residual bone, delayed placement, width of residual bone, graft volume immediately after surgery (V1), graft volume 6 months after surgery (V2), or volumetric change rate between the test group and the control group (P>0.05). Graft volume V2 was remarkably decreased compared with V1 in the control and test groups (P=0.01). There were no significant differences for bone height immediately after surgery (H1) and bone height at 6 months after surgery (H2) between the 2 groups. Bone height H2 was markedly decreased compared with H1 (P<0.05). At 1 year after implantation, there was 1 implant loss in the control group and 2 in the test group. The implant survival rate in the control group was 97.62% and 95.24% in the test group. CONCLUSIONS Absorbable gelatin sponge combined with bovine bone particles was an effective and economical material for use in routine sinus floor elevation surgery.

Effects of the Screw-Access Hole Diameter on the Biomechanical Behaviors of 4 Types of Cement-Retained Implant Prosthodontic Systems and Their Surrounding Cortical Bones: A 3D Finite Element Analysis.

PURPOSE: To investigate the effect(s) of screw-access hole (SAH) in different diameters on the cement-retained implant prosthodontic systems and surrounding cortical bones. MATERIALS AND METHODS: Twenty finite element models were divided into 4 groups: 2 types of full-contour (FC) crowns (Y-TZP, gold alloy) and 2 types of porcelain-fused-to-metal crowns (based on Co-Cr, Au-Pd alloy). For each group, 5 crowns were simulated by varying the diameter of SAH (0, 1, 2, 3, and 4 mm). A vertical load of 200 N and an oblique load of 100 N (45°s) were applied. All models were analyzed with finite element analysis software. RESULTS: The stress on the occlusal surface of crowns was almost unchanged when the SAH was within 0 to 3 mm, whereas it showed an obvious increase when it reached 4 mm. The stress concentration was also suddenly changed from the loading area to the hole margin under vertical loading. As for the screw, a lower stress level was observed in vertical loading when an FC crown with an SAH within 0 to 1 mm was applied. The stress concentration was constantly located at the beginning of the first thread. Stresses of other components remained almost unchanged. CONCLUSIONS: From the aspect of biomechanics, an FC crown with a 1-mm access hole is recommended when a combined cement- and screw-retained crown was used in the posterior region.

Accuracy of dynamic navigation compared to static surgical guides and the freehand approach in implant placement: a prospective clinical study.

BACKGROUND: Computer-guided implant surgery has improved the quality of implant treatment by facilitating the placement of implants in a more accurate manner. This study aimed to assess the accuracy of implant placement in a clinical setting using three techniques: dynamic navigation, static surgical guides, and freehand placement. We also investigated potential factors influencing accuracy to provide a comprehensive evaluation of each technique's advantages and disadvantages. MATERIALS AND METHODS: Ninety-four implants in 65 patients were included in this prospective study. Patients were randomly assigned to one of three groups: dynamic navigation, static surgical guides, or freehand placement. Implants were placed using a prosthetically oriented digital implant planning approach, and postoperative CBCT scans were superimposed on preoperative plans to measure accuracy. Seven deviation values were calculated, including angular, platform, and apical deviations. Demographic and consistency analyses were performed, along with one-way ANOVA and post-hoc tests for deviation values. RESULTS: The mean global platform, global apical, and angular deviations were 0.99 mm (SD 0.52), 1.14 mm (SD 0.56), and 3.66° (SD 1.64°) for the dynamic navigation group; 0.92 mm (SD 0.36), 1.06 mm (SD 0.47), and 2.52° (SD 1.18°) for the surgical guide group; and 1.36 mm (SD 0.62), 1.73 mm (SD 0.66), and 5.82° (SD 2.79°) for the freehand group. Both the dynamic navigation and surgical guide groups exhibited statistically significant differences in all values except depth deviations compared to the freehand group (p < 0.05), whereas only the angular deviation showed a significant difference between the dynamic navigation and surgical guide groups (p = 0.002). CONCLUSION: Our findings highlight the superior accuracy and consistency of dynamic navigation and static surgical guides compared to freehand placement in implant surgery. Dynamic navigation offers precision and flexibility. However, it comes with cost and convenience considerations. Future research should focus on improving its practicality. TRIAL REGISTRATION: This study was retrospectively registered at the Thai Clinical Trials Register-Medical Research Foundation of Thailand (MRF) with the TCTR identification number TCTR20230804001 on 04/08/2023. It was also conducted in accordance with the Declaration of Helsinki and approved by the institutional ethics committee at the Xian Jiaotong University Hospital of Stomatology, Xian, China (xjkqII[2021] No: 043). Written informed consent was obtained from all participants.

Sinus floor elevation using osteotome technique without grafting materials: a 2-year retrospective study.

OBJECTIVE: The study aimed to assess the clinical results after osteotome technique to lift sinus floor, without graft materials in the residual bone height (RBH), below 8 mm. MATERIAL AND METHODS: Twenty-two patients aged from 19 to 70 years old in need of maxillary sinus floor augmentation were enrolled in this study. Preoperative and postoperative cone beam computerized tomography (CBCT) were taken to guide the surgery. Twenty-seven implants were inserted and followed clinically, another CBCT exam was taken at 6 months postoperatively. The diameter of the implants was 4.7 mm (SD 0.4 mm), the length was 10 mm (SD 1.0 mm). The average residual bone height was 6.7 mm (SD 1.2 mm). RESULTS: No implants were lost after the surgery and the 2 years follow-up. There was no obvious marginal bone loss during the 6 months follow-up verified by CBCT. The mean bone gain at the implant sites was 2.5 mm (SD 1.5 mm). CONCLUSION: The study verified the good and stable clinical result of the OSFE technique without using bone grafting materials when the RBH was only 4.1-8 mm.

Effect of co-precipitation plus spray-drying of nano-CaF2 on mechanical and fluoride properties of nanocomposite.

OBJECTIVE: Fluoride (F)-releasing restoratives typically are either weak mechanically or release only low levels of F ions. The objectives of this study were to: (1) develop a novel photo-cured nanocomposite with strong mechanical properties and high levels of sustained F ion release via a two-step "co-precipitation + spray-drying" technique to synthesize CaF2 nanoparticles (nCaF2); and (2) investigate the effect of spray-drying treatment after co-precipitation of nCaF2 on mechanical properties and F ion release of composite. METHODS: Two types of CaF2 particles were synthesized: A co-precipitation method yielded CaF2cp; "co-precipitation + spray-drying" yielded nCaF2cpsd. Composites were fabricated with fillers of: (1) 0% CaF2 + 70% glass; (2) 10% CaF2cp + 60% glass; (3) 15% CaF2cp + 55% glass; (4) 20% CaF2cp + 50% glass; (5) 10% nCaF2cpsd + 60% glass; (6) 15% nCaF2cpsd + 55% glass; and (7) 20% nCaF2cpsd + 50% glass. A commercial F-releasing nanocomposite served as control. RESULTS: The nCaF2cpsd had much smaller particle size (median = 32 nm) and narrower distribution (22-57 nm) than CaF2cp (median = 5.25 µm, 162 nm-67 µm). The composite containing nCaF2cpsd had greater flowability, flexural strength, elastic modulus and hardness than CaF2cp composite and commercial control composite. At 84-day immersion in water, the nanocomposites containing 20% nCaF2cpsd had 65 times higher cumulative F release, and 77 times greater long-term F-release rate, than commercial control. CONCLUSIONS: A novel two-step "co-precipitation + spray-drying" technique of synthesizing nCaF2 was developed. The photo-cured nanocomposite containing 20% nCaF2cpsd possessed strong mechanical properties and excellent long-term F-release ability, and hence is promising for dental restoration applications to inhibit secondary caries.

Periodontal Bone-Ligament-Cementum Regeneration via Scaffolds and Stem Cells.

Periodontitis is a prevalent infectious disease worldwide, causing the damage of periodontal support tissues, which can eventually lead to tooth loss. The goal of periodontal treatment is to control the infections and reconstruct the structure and function of periodontal tissues including cementum, periodontal ligament (PDL) fibers, and bone. The regeneration of these three types of tissues, including the re-formation of the oriented PDL fibers to be attached firmly to the new cementum and alveolar bone, remains a major challenge. This article represents the first systematic review on the cutting-edge researches on the regeneration of all three types of periodontal tissues and the simultaneous regeneration of the entire bone-PDL-cementum complex, via stem cells, bio-printing, gene therapy, and layered bio-mimetic technologies. This article primarily includes bone regeneration; PDL regeneration; cementum regeneration; endogenous cell-homing and host-mobilized stem cells; 3D bio-printing and generation of the oriented PDL fibers; gene therapy-based approaches for periodontal regeneration; regenerating the bone-PDL-cementum complex via layered materials and cells. These novel developments in stem cell technology and bioactive and bio-mimetic scaffolds are highly promising to substantially enhance the periodontal regeneration including both hard and soft tissues, with applicability to other therapies in the oral and maxillofacial region.

Self-healing adhesive with antibacterial activity in water-aging for 12 months.

OBJECTIVE: Secondary caries and micro-cracks are the main limiting factors for dentin bond durability. The objectives of this study were to develop a self-healing adhesive containing dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and investigate the effects of water-aging for 12 months on self-healing, dentin bonding, and antibacterial properties for the first time. METHODS: Microcapsules were synthesized with poly (urea-formaldehyde) (PUF) shells containing triethylene glycol dimethacrylate (TEGDMA) and N,N-dihydroxyethyl-p-toluidine (DHEPT). The adhesive contained 7.5% microcapsules, 10% DMAHDM, and 20% NACP (all mass). Specimens were water-aged at 37 °C for 1 day to 12 months. Dentin bond strength was measured using extracted human teeth. A single-edge-V-notched-beam (SEVNB) method was used to measure fracture toughness KIC and self-healing efficiency. A dental plaque microcosm biofilm model was used with human saliva as inoculum. RESULTS: The microcapsules + DMAHDM + NACP group showed no decline in dentin bond strength after water-aging for 12 months, which was significantly higher than that of other groups without DMAHDM (p < 0.05). A self-healing efficiency of 67% recovery in KIC was obtained even after 12 months of water immersion, indicating that the self-healing ability was not lost in water-aging (p > 0.1). The bacteria-killing ability of this adhesive did not decline from 1 day to 12 months (p > 0.1), with biofilm CFU reduction by 3-4 orders of magnitude after the resin was water-aged for 12 months, compared to control resin. SIGNIFICANCE: This novel adhesive with triple merits of self-healing, antibacterial and remineralization functions showed an excellent long-term durability in water-aging for 12 months. This multifunctional adhesive has the potential for dental applications to heal cracks, inhibit bacteria, provide ions for remineralization, and increase the restoration longevity.

Calcium phosphate cement scaffold with stem cell co-culture and prevascularization for dental and craniofacial bone tissue engineering.

OBJECTIVE: Calcium phosphate cements (CPCs) mimic nanostructured bone minerals and are promising for dental, craniofacial and orthopedic applications. Vascularization plays a critical role in bone regeneration. This article represents the first review on cutting-edge research on prevascularization of CPC scaffolds to enhance bone regeneration. METHODS: This article first presented the prevascularization of CPC scaffolds. Then the co-culture of two cell types in CPC scaffolds was discussed. Subsequently, to further enhance the prevascularization efficacy, tri-culture of three different cell types in CPC scaffolds was presented. RESULTS: (1) Arg-Gly-Asp (RGD) incorporation in CPC bone cement scaffold greatly enhanced cell affinity and bone prevascularization; (2) By introducing endothelial cells into the culture of osteogenic cells (co-culture of two different cell types, or bi-culture) in CPC scaffold, the bone defect area underwent much better angiogenic and osteogenic processes when compared to mono-culture; (3) Tri-culture with an additional cell type of perivascular cells (such as pericytes) resulted in a substantially enhanced prevascularization of CPC scaffolds in vitro and more new bone and blood vessels in vivo, compared to bi-culture. Furthermore, biological cell crosstalk and capillary-like structure formation made critical contributions to the bi-culture system. In addition, the pericytes in the tri-culture system substantially promoted stability and maturation of the primary vascular network. SIGNIFICANCE: The novel approach of CPC scaffolds with stem cell bi-culture and tri-culture is of great significance in the regeneration of dental, craniofacial and orthopedic defects in clinical practice.

Bonding durability, antibacterial activity and biofilm pH of novel adhesive containing antibacterial monomer and nanoparticles of amorphous calcium phosphate.

OBJECTIVES: The dentin bonding often fails over time, leading to secondary caries and restoration failure. The objectives of this study were to develop an adhesive with dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP), and investigate the effects of storage in artificial saliva for six months on the bonding durability, antibacterial activity, ion release and biofilm pH properties for the first time. METHODS: DMAHDM was added at 5% (by mass) to Scotchbond Primer and Adhesive (SBMP). NACP was added at 10%, 20%, and 30% to SBMP adhesive. Dentin bonding durability, antibacterial activity against Streptococcus mutans biofilms, and calcium (Ca) and phosphate (P) ion liberation properties were investigated after 1 day and 6months of storage in artificial saliva. RESULTS: Dentin bond strength (n = 50) had 25% loss after 6 months of aging for SBMP control. However, SBMP + DMAHDM+10NACP and SBMP + DMAHDM+20NACP showed no loss in bond strength after storage in artificial saliva for 6 months. The DMAHDM + NACP incorporation method dramatically reduced the biofilm metabolic activity and acid production, and decreased the biofilm CFU by four orders of magnitude, compared to SBMP control, even after 6 months of aging (p < 0.05). DMAHDM + NACP had long-lasting Ca and P ion releases, and raised the biofilm pH to 6.8, while the control group had a cariogenic biofilm pH of 4.5. CONCLUSIONS: Incorporating DMAHDM + NACP in bonding agent yielded potent and long-lasting antibacterial activity and ions liberation ability, and much higher long-term dentin bond strength after 6-month of aging. The new bonding agent is promising to inhibit caries at the restoration margins and increase the resin-dentin bonding longevity. CLINICAL SIGNIFICANCE: The novel bioactive adhesive is promising to protect tooth structures from biofilm acids and secondary caries. NACP and DMAHDM have great potential for applications to a wide range of dental materials to reduce plaque and achieve therapeutic effects.

[Methods of removing failed implants].

Implant restoration has become one of the most regular methods of restoring dentition defect or edentulous. Implant placement and osseointegration are partly unreserved (fracture, implant is not in the correct three-dimensional position and cannot be repaired, peri-implantitis-affected nonmobile implants) need to be removed. This article reviews the different methods of removing implants and discusses the limitations of each method, as well as the complications that may occur during the procedure.

Novel magnetic nanoparticle-containing adhesive with greater dentin bond strength and antibacterial and remineralizing capabilities.

OBJECTIVES: A nanoparticle-doped adhesive that can be controlled with magnetic forces was recently developed to deliver drugs to the pulp and improve adhesive penetration into dentin. However, it did not have bactericidal and remineralization abilities. The objectives of this study were to: (1) develop a magnetic nanoparticle-containing adhesive with dimethylaminohexadecyl methacrylate (DMAHDM), amorphous calcium phosphate nanoparticles (NACP) and magnetic nanoparticles (MNP); and (2) investigate the effects on dentin bond strength, calcium (Ca) and phosphate (P) ion release and anti-biofilm properties. METHODS: MNP, DMAHDM and NACP were mixed into Scotchbond SBMP at 2%, 5% and 20% by mass, respectively. Two types of magnetic nanoparticles were used: acrylate-functionalized iron nanoparticles (AINPs); and iron oxide nanoparticles (IONPs). Each type was added into the resin at 1% by mass. Dentin bonding was performed with a magnetic force application for 3min, provided by a commercial cube-shaped magnet. Dentin shear bond strengths were measured. Streptococcus mutans biofilms were grown on resins, and metabolic activity, lactic acid and colony-forming units (CFU) were determined. Ca and P ion concentrations in, and pH of biofilm culture medium were measured. RESULTS: Magnetic nanoparticle-containing adhesive using magnetic force increased the dentin shear bond strength by 59% over SBMP Control (p<0.05). Adding DMAHDM and NACP did not adversely affect the dentin bond strength (p>0.05). The adhesive with MNP+DMAHDM+NACP reduced the S. mutans biofilm CFU by 4 logs. For the adhesive with NACP, the biofilm medium became a Ca and P ion reservoir. The biofilm culture medium of the magnetic nanoparticle-containing adhesive with NACP had a safe pH of 6.9, while the biofilm medium of commercial adhesive had a cariogenic pH of 4.5. SIGNIFICANCE: Magnetic nanoparticle-containing adhesive with DMAHDM and NACP under a magnetic force yielded much greater dentin bond strength than commercial control. The novel adhesive reduced biofilm CFU by 4 logs and increased the biofilm pH from a cariogenic pH 4.5-6.9, and therefore is promising to enhance the resin-tooth bond, strengthen tooth structures, and suppress secondary caries at the restoration margins.

Novel bioactive root canal sealer to inhibit endodontic multispecies biofilms with remineralizing calcium phosphate ions.

OBJECTIVE: The objectives of this study were to: (1) develop a bioactive endodontic sealer via dimethylaminohexadecyl methacrylate (DMAHDM), 2-methacryloyloxyethyl phosphorylcholine (MPC) and nanoparticles of amorphous calcium phosphate (NACP) for the first time; and (2) evaluate inhibition of early-stage and mature multispecies endodontic biofilm, bond strength to root canal dentine, and calcium (Ca) and phosphate (P) ion release. METHODS: A series of bioactive endodontic sealers were formulated with DMAHDM, MPC, and NACP. Root dentine bond strength was measured via a push-out test. Three endodontic strains, Enterococcus faecalis, Actinomyces naeslundii, and Fusobacterium nucleatum, were grown on endodontic sealer disks to form multispecies biofilms. Biofilms were grown for 3 days (early) and 14 days (mature). Colony-forming units (CFU), live/dead assay, metabolic activity and polysaccharide were determined. Ca and P ion release from endodontic sealer was measured. RESULTS: Incorporating DMAHDM, MPC and NACP did not decrease the push-out bond strength (p>0.1). Adding DMAHDM and MPC reduced endodontic biofilm CFU by 3 log. DMAHDM or MPC each greatly decreased the biofilm CFU (p<0.05). Endodontic sealer with DMAHDM+MPC had much greater killing efficacy than DMAHDM or MPC alone (p<0.05). Endodontic sealer with DMAHDM+MPC had slightly lower, but not significantly lower, Ca and P ion release compared to that without DMAHDM+MPC (p>0.1). CONCLUSIONS: A novel bioactive endodontic sealer was developed with potent inhibition of multispecies endodontic biofilms, reducing biofilm CFU by 3 log, while containing NACP for remineralization and possessing good bond strength to root canal dentine walls. CLINICAL SIGNIFICANCE: The new bioactive endodontic sealer is promising for endodontic applications to eradicate endodontic biofilms and strengthen root structures. The combination of DMAHDM, MPC and NACP may be applicable to other preventive and restoration resins.

Novel self-healing dental luting cements with microcapsules for indirect restorations.

OBJECTIVES: Dental luting cements are widely used to bond indirect restorations to teeth. Microcracks often lead to cement failures. The objectives of this study were to develop the first self-healing luting cement, and investigate dentin bond strength, mechanical properties, crack-healing, and self-healing durability in water-aging for 6 months. METHODS: Microcapsules of poly(urea-formaldehyde) (PUF) shells with triethylene glycol dimethacrylate (TEGDMA) as healing liquid were synthesized. Cement contained bisphenol A glycidyl dimethacrylate, TEGDMA, 4-methacryloyloxyethyl trimellitic and glass fillers. Microcapsules were added at 0%, 2.5%, 5%, 7.5%, 8.5%, 9.5% and 10%. Dentin shear bond strength was measured using extracted human teeth. Flexural strength and elastic modulus were measured. Single edge V-notched beams were used to measure fracture toughness (KIC) and self-healing. Specimens were water-aged at 37°C for 6 months and then tested for self-healing durability. RESULTS: Adding 7.5% microcapsules into cement achieved effective self-healing, without adverse effects on dentin bond strength and virgin mechanical properties (p>0.1). Excellent self-healing of 68%-77% recovery was obtained. Six months of water-aging did not decrease the self-healing efficiency, compared to 1 d (p>0.1), indicating that the self-healing property did not degrade in water-aging. CONCLUSIONS: A self-healing dental luting cement was developed for the first time. It contained fine microcapsules and exhibited an excellent self-healing efficiency, even after being immersed in water for 6 months. CLINICAL SIGNIFICANCE: The self-healing cement is promising for cementing crowns and bridges and other adhesive cement applications, to heal cracks and increase restoration longevity.

Effect of calcium phosphate nanocomposite on in vitro remineralization of human dentin lesions.

OBJECTIVE: Secondary caries is a primary reason for dental restoration failures. The objective of this study was to investigate the remineralization of human dentin lesions in vitro via restorations using nanocomposites containing nanoparticles of amorphous calcium phosphate (NACP) or NACP and tetracalcium phosphate (TTCP) for the first time. METHODS: NACP was synthesized by a spray-drying technique and incorporated into a resin consisting of ethoxylated bisphenol A dimethacrylate (EBPADMA) and pyromellitic glycerol dimethacrylate (PMGDM). After restoring the dentin lesions with nanocomposites as well as a non-releasing commercial composite control, the specimens were treated with cyclic demineralization (pH 4, 1h per day) and remineralization (pH 7, 23h per day) for 4 or 8 weeks. Calcium (Ca) and phosphate (P) ion releases from composites were measured. Dentin lesion remineralization was measured at 4 and 8 weeks by transverse microradiography (TMR). RESULTS: Lowering the pH increased ion release of NACP and NACP-TTCP composites. At 56 days, the released Ca concentration in mmol/L (mean±SD; n=3) was (13.39±0.72) at pH 4, much higher than (1.19±0.06) at pH 7 (p<0.05). At 56 days, P ion concentration was (5.59±0.28) at pH 4, much higher than (0.26±0.01) at pH 7 (p<0.05). Quantitative microradiography showed typical subsurface dentin lesions prior to the cyclic demineralization/remineralization treatment, and dentin remineralization via NACP and NACP-TTCP composites after 4 and 8 weeks of treatment. At 8 weeks, NACP nanocomposite achieved dentin lesion remineralization (mean±SD; n=15) of (48.2±11.0)%, much higher than (5.0±7.2)% for dentin in commercial composite group after the same cyclic demineralization/remineralization regimen (p<0.05). SIGNIFICANCE: Novel NACP-based nanocomposites were demonstrated to achieve dentin lesion remineralization for the first time. These results, coupled with acid-neutralization and good mechanical properties shown previously, indicate that the NACP-based nanocomposites are promising for restorations to inhibit caries and protect tooth structures.