The effect of surface roughening on the success of orthodontic mini-implants: A systematic review and meta-analysis.

INTRODUCTION: Orthodontic mini-implants are a widely accepted treatment modality in orthodontics; however, the failure rate is moderately high. Surface roughening is the golden standard in conventional oral implantology, and this may prove beneficial for orthodontic mini-implants as well. The objective of this systematic review is to assess the effect of surface roughening on the success rate of orthodontic mini-implants in both adolescent and adult patients undergoing orthodontic treatment. METHODS: Randomized studies comparing the success of surface-roughened and smooth, machined-surface orthodontic mini-implants were included. A literature search was conducted for 6 electronic databases (Pubmed/Medline, Embase, Cochrane, CINAHL, Web of Science, and Scopus), Clinical trial registry (https://www. CLINICALTRIALS: gov), and grey literature (Google Scholar). A manual search of the reference lists of included studies was performed. Two authors independently performed the screening, data extraction, risk of bias, and quality assessments. The risk of bias was assessed with the Cochrane risk-of-bias 2.0 Tool. Data were synthesized using a random effect model meta-analysis presented as a forest plot. The certainty in the body of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation tool. RESULTS: A total of 4226 unique records were screened, and 6 of these were included in the quantitative analysis. Four additional articles were selected for a secondary outcome. A total of 364 orthodontic mini-implants were included in the primary outcome analysis. There was no statistically significant effect of surface roughening on the success of orthodontic mini-implants (odds ratio = 0.63 favoring roughened orthodontic mini-implants; 95% confidence interval, 0.35-1.14). The secondary outcome (ie, the overall failure rate of roughened orthodontic mini-implants) was 6% based on studies with high heterogeneity. Limitations of this study were the risk of bias, study imprecision, and possible publication bias, leading to a very low certainty in the body of evidence. CONCLUSIONS: There is very low-quality evidence that there is no statistically significant effect of surface roughening on the success of orthodontic mini-implants in humans. The overall failure rate of surface-roughened orthodontic mini-implants was 6%. FUNDING: No funding was received for this review. REGISTRATION: This study was preregistered in the Prospective Register of Systematic Reviews (CRD42022371830).

Innovative implant design for continuous implant stability: A mechanical and histological experimental study in the iliac crest of goats.

OBJECTIVES: this in vivo study reports on mechanical torque data as well as the biological evaluation up to 6 weeks after placement of implants with a unique wide knife thread design in a goat iliac crest model. We hypothesized that implants with this thread design would show substantial primary stability at a continuous level toward secondary stability. METHODS: 64 MegaGen Anyridge® implants were used with diameters 3.5 mm, 4.0 mm, 5.0 mm and 6.0 mm (n = 8). Implants were placed monocortically in the iliac crest of 16 healthy female Saanen goats, both on the right (for torque measurements) and left side (for histology/-morphometry). Torque-in at implant installation and torque-out at 2 and 6 weeks of implantation was measured, as well as bone-to-implant contact (BIC) and bone-area between the screw threads (BA). RESULTS: Histology showed intimate bone-to-implant contact with a maturating trabecular structure between 2 and 6 weeks. Torque values showed a dependency on implant diameter. For all implant diameters, torque-in values were similar to torque-out values at 2 weeks. At 6 weeks however, all torque-out values were significantly increased. BIC and BA percentages showed similar values for all diameters at both 2 and 6 weeks. CONCLUSIONS: These results prove the absence of a lag-phase in implant stability for MegaGen Anyridge® implants in the goat iliac crest model. The increased torque-out values at 6 weeks without increasing BIC and BA percentages correlate with the observed maturation of bone-to-implant contact quality over time. CLINICAL SIGNIFICANCE: It is a challenge to optimize implants with continuous primary stability and rapid transition into secondary stability to minimize the duration of the lag-phase. The results of this study prove the absence of a lag-phase in implant stability for MegaGen Anyridge® implants. Consequently, the data from this work are important for the treatment of individual patients 'translating' these findings into clinical implant procedures.

Long-term biological performance of injectable and degradable calcium phosphate cement.

Enhancing degradation of poorly degrading injectable calcium phosphate (CaP) cements (CPCs) can be achieved by adding poly(lactic-co-glycolic acid) (PLGA) microparticles, generating porosity after polymer degradation. CPC-PLGA has proven to be biodegradable, although its long-term biological performance is still unknown. Optimization of injectability could be achieved via addition of carboxymethyl cellulose (CMC). Here, we evaluated the long-term in vivo performance of CPC-PLGA with or without the lubricant CMC in comparison to the devitalized bovine bone mineral (DBBM) predicate device Bio-Oss®. Rabbit femoral bone defects were injected with a CPC-formulation or filled with Bio-Oss® granules. Samples were retrieved at 6 and 26 weeks. Material degradation for Bio-Oss® was marginal, starting with 57% material remnants at implantation, 49% at 6 weeks, and 35% at 26 weeks, respectively. In contrast, CPC-PLGA and CPC-PLGA-CMC showed significant material degradation, starting with 100% material remnants at implantation, 56 and 78% at 6 weeks, and 8 and 21% at 26 weeks. Bone formation showed to be rapid for Bio-Oss®, with 24% at 6 weeks, and a similar value (27%) at 26 weeks. Both CPC-PLGA and CPC-PLGA-CMC showed a continuous temporal increase in bone formation, with 13 and 6% at 6 weeks, and 44 and 32% at 26 weeks. This study showed that CPC-PLGA induces favorable bone responses with >90% degradation and >40% new bone formation after an implantation period of 26 weeks.

Tantalum oxide and barium sulfate as radiopacifiers in injectable calcium phosphate-poly(lactic-co-glycolic acid) cements for monitoring in vivo degradation.

Monitoring the degradation of calcium phosphate-based bone substitute materials in vivo by means of noninvasive techniques (e.g., radiography) is often a problem due to the chemical resemblance of those substitutes with the mineral phase of bone. In the view of that, the present study aimed at enhancing the radiopacity of calcium phosphate cement enriched with poly(lactic-co-glycolic acid) (CPC-PLGA) microspheres, by adding tantalum oxide (Ta2O5) or the more traditional radiopacifier barium sulfate (BaSO4). The radiopacifying capacity of these radiopacifiers was first evaluated in vitro by microcomputed tomography (µCT). Thereafter, both radiopacifiers were tested in vivo using a distal femoral condyle model in rabbits, with subsequent ex vivo µCT analysis in parallel with histomorphometry. Addition of either one of the radiopacifiers proved to enhance radiopacity of CPC-PLGA in vitro. The in vivo experiment showed that both radiopacifiers did not induce alterations in biological performance compared to plain CPC-PLGA, hence both radiopacifiers can be considered safe and biocompatible. The histomorphometrical assessment of cement degradation and bone formation showed similar values for the three experimental groups. Interestingly, µCT analysis showed that monitoring cement degradation becomes feasible upon incorporation of either type of radiopacifier, albeit that BaSO4 showed more accuracy compared to Ta2O5.

The in vivo performance of CaP/PLGA composites with varied PLGA microsphere sizes and inorganic compositions.

Enrichment of calcium phosphate (CaP) bone substitutes with poly(lactic-co-glycolic acid) (PLGA) microspheres to create porosity overcomes the problem of poor CaP degradation. The degradation of CaP-PLGA composites can be customized by changing the physical and chemical properties of PLGA and/or CaP. However, the effect of the size of dense (solid rather than hollow) PLGA microspheres in CaP has not previously been described. The present study aimed at determining the effect of different dense (i.e. solid) PLGA microsphere sizes (small (S) ~20µm vs. large (L) ~130µm) and of CaP composition (CaP with either anhydrous dicalcium phosphate (DCP) or calcium sulphate dihydrate (CSD)) on CaP scaffold biodegradability and subsequent bone in-growth. To this end mandibular defects in minipigs were filled with pre-set CaP-PLGA implants, with autologous bone being used as a control. After 4weeks the autologous bone group outperformed all CaP-PLGA groups in terms of the amount of bone present at the defect site. On the other hand, at 12weeks substantial bone formation was observed for all CaP-PLGA groups (ranging from 47±25% to 62±15%), showing equal amounts of bone compared with the autologous bone group (82±9%), except for CaP with DCP and large PLGA microspheres (47±25%). It was concluded that in the current study design the difference in PLGA microsphere size and CaP composition led to similar results with respect to scaffold degradation and subsequent bone in-growth. Further, after 12weeks all CaP-PLGA composites proved to be effective for bone substitution.

Maxillary sinus floor augmentation with injectable calcium phosphate cements: a pre-clinical study in sheep.

OBJECTIVES: The aim of this pre-clinical study was to evaluate the biological performance of two injectable calcium phosphate cement (CPC) composite materials containing poly(D,L-lactic-co-glycolic)acid (PLGA) microspheres with different properties in a maxillary sinus floor elevation model in sheep. MATERIALS AND METHODS: PLGA microspheres were made of either low molecular weight (~17 kDa) acid-terminated PLGA (PLGA(L-AT) ) or high molecular weight (~44 kDa) end-capped PLGA (PLGA(H-EC) ) and incorporated in CPC. Eight female Swifter sheep underwent a bilateral maxillary sinus floor elevation procedure via an extra-oral approach. All animals received both materials, alternately injected in the left and right sinus (split-mouth model) and a time point of 12 weeks was used. Analysis of biological performance was based on histology, histomorphometry, and evaluation of sequential fluorochrome labeling. RESULTS: Both types of CPC-PLGA composites showed biocompatibility and direct bone-cement contact. CPC-PLGA(L-AT) showed a significantly higher degradation distance compared to CPC-PLGA(H-EC) (1949 ± 1295 µm vs. 459 ± 267 µm; P = 0.0107). Further, CPC-PLGA(L-AT) showed significantly more bone in the region of interest (26.4 ± 10.5% vs. 8.6 ± 3.9% for PLGA(H-EC) ; P = 0.0009) and significantly less remaining CPC material (61.2 ± 17.7% vs. 81.9 ± 10.9% for PLGA(H-EC) ; P = 0.0192). CONCLUSIONS: Both CPC-PLGA(L-AT) and CPC-PLGA(H-EC) demonstrated to be safe materials for sinus floor elevation procedures in a large animal model, presenting biocompatibility and direct bone contact. In view of material performance, CPC-PLGA(L-AT) showed significantly faster degradation and a significantly higher amount of newly formed bone compared to CPC-PLGA(H-EC) .

Tantalumpentoxide as a radiopacifier in injectable calcium phosphate cements for bone substitution.

The chemical resemblance of calcium phosphate (CaP) cements and the mineral phase of bone is a problem in distinguishing CaP cement from bone tissue by means of common, noninvasive techniques (e.g., X-ray imaging and microcomputed tomography [µCT]). In this study, the feasibility of using tantalumpentoxide (Ta(2)O(5)) powder as radiopacifier in CaP cements was analyzed. A distal femoral condyle model in male adult Wistar rats was used. After 6 weeks of implantation time, the results were analyzed by means of µCT and histology. Unambiguous distinction of CaP cement from native bone tissue and volumetric measurements of the materials appeared to be possible by means of µCT scanning. Furthermore, there was no evidence of either inflammation or fibrous tissue around the implant materials or at the bone-material interface. In conclusion, the addition of Ta(2)O(5) as a radiopacifying additive to CaP cements allows discrimination between bone substitute and surrounding bone tissue. Consequently, Ta(2)O(5) represents an effective and biocompatible additive in CaP cements for in vivo monitoring purposes.

Late (> 5 years) regional lymph node metastasis of oral squamous cell carcinoma (SCC), proven by p53 mutation analysis.

BACKGROUND: A late (> 5 years) neck nodal metastasis of oral cancer, poses a problem to the clinician: is it a late metastasis or a metastasis of a (unknown) second primary tumour? METHODS: A 50-year-old male was seen with a contralateral lymph node metastasis, 5 1/2 years after treatment of a pT2N1M0 carcinoma in the floor of the mouth. Both the late metastasis and the original tumour specimen were analysed for p53 mutations. RESULTS: Both specimens showed an identical p53 mutation, thereby confirming the lymph node to be a late metastasis. CONCLUSIONS: A lymph node metastasis can occur more than 5 years after treatment of an oral squamous cell carcinoma. p53 mutation analysis is of help to discriminate it from a second primary tumour.