Michal Halperin-Sternfeld

Diagnostic accuracy of cone beam computed tomography for dimensional linear measurements in the mandible.

PURPOSE To compare linear measurements made on cone beam computed tomography (CBCT) images to direct measurements in ex vivo porcine mandibles. MATERIALS AND METHODS Six cross-sectional planes were defined by gutta-percha-filled cavities in seven mandibles. The mandibles were scanned in a CBCT apparatus and later sectioned, using a band saw, through the gutta-percha markers. Next, four direct (DIR) linear measurements were performed for each section with a handheld digital caliper, using the gutta-percha markers as reference points. The corresponding radiographic (RAD) cross sections were then measured using dedicated software. A total of 168 sites were measured. Differences between RAD and DIR measurements [Δ (RAD - DIR)] were calculated for each pair individually. RESULTS Mean Δ (RAD - DIR) was -0.17 ± 0.53 mm (range, -1.42 to 1.09 mm). CBCT overestimated direct measurements at 36% of the sites; 8% of sites (95% confidence interval, 3.8% to 12.2%) showed errors between +0.5 and +1 mm, and 1.8% (95% confidence interval, -0.2% to 3.9%) showed errors greater than +1 mm. CONCLUSIONS Good correlation was found between CBCT and direct measurements. However, the significant percentage of sites with overestimation of at least 0.5 mm indicates a need for safety margins to be maintained when CBCT is used to plan surgical interventions such as dental implant therapy.

Variables affecting tooth survival and changes in probing depth: a long-term follow-up of periodontitis patients.

AIM To retrospectively assess tooth-survival rate and its association with patient and oral variables in periodontal office patients, followed up to 18 years. MATERIAL AND METHODS Patients in a private periodontal office whose files included initial examination (T0 ), reevaluation (TRe ) and ≥ 10 years after T0 (TF ) chartings, and received periodontal therapy and supportive periodontal therapy (SPT) after TRe were included. General health, plaque scores (PI), probing depth (PPD), bleeding on probing (BOP) at six points/tooth, tooth extractions, and SPT visits were extracted from patient files at T0 , TRe , and TF . Descriptive statistics and Cox regression analysis were performed. RESULTS Fifty patients (mean 26 ± 4 teeth/patient, 1301 teeth) fulfilled inclusion criteria. About 20 and 129 teeth respectively were extracted before/after TRe , 96 of them for periodontal causes. PPD>7 mm at TRe (HR = 17.7, 95%CI 8.6, 36.6), age above 60 years (HR = 3.3, 95%CI 1.5, 7.2), multi-rooted teeth (HR = 1.9, 95%CI 1.2, 3.1) and SPT<3 times/year (HR = 1.8, 95%CI 1.1, 2.9), were the best prognostic factors for tooth loss during follow-up. (p < 0.05, Cox regression analysis). A continuous, statistically significant reduction was observed in mean PPD among teeth that survived follow-up [4.3 ± 1.8 mm, 3.5 ± 1.4 mm, 3.2 ± 1.3 mm, at T0 , TRe , TF , respectively. (p < 0.001, Repeated-measures test)]. CONCLUSION Regular SPT was associated with low tooth-loss rates and continuous reductions in probing depth. PPD after initial therapy, age above 60, multi-rooted teeth and infrequent SPT were strong negative prognostic factors for long-term tooth survival among periodontal patients.

Arginine-Presenting Peptide Hydrogels Decorated with Hydroxyapatite as Biomimetic Scaffolds for Bone Regeneration

Hydrogels are promising candidates for biomimetic scaffolds of the extracellular matrix in tissue engineering applications. However, their use in bone tissue engineering is limited due to their low mechanical properties. In this study, we designed and synthesized multicomponent peptide-based hydrogels composed of fluorenyl-9-methoxycarbonyl diphenylalanine (FmocFF), which contributed to the rigidity and stability of the hydrogel, and Fmoc-arginine (FmocR), which mediated high affinity to hydroxyapatite (HAP) due to the arginine moiety. The new hydrogels composed of nanometric fibril networks were decorated with HAP and demonstrated high mechanical strength with a storage modulus of up to 29 kPa. In addition, the hydrogels supported cell adhesion and in vitro cell viability. These properties suggest using these multicomponent organic-inorganic hydrogels as functional biomaterials for improved bone regeneration.

Dimensional changes of the maxillary sinus following tooth extraction in the posterior maxilla with and without socket preservation

BACKGROUND Sinus pneumatization is commonly observed following tooth extraction in the posterior maxilla, however, the role of this pneumatization in the overall changes in the vertical bone height is not clear. PURPOSE To compare dimensional changes in the alveolar ridge and corresponding maxillary sinus following tooth extraction, with or without socket preservation. MATERIALS AND METHODS 42 patients underwent tooth extraction (control group) and 21 patients underwent tooth extraction with socket preservation using DBBM (study group). Panoramic radiographs, prior to and approximately 1 year post extractions were superimposed and matched using a fixed reference unit. The following measurements were performed in the midline of the tooth site: distance of the bone crest to the sinus floor; distance of the sinus floor to the sinus roof and the sagittal circumference of the maxillary. RESULTS The mean change in the distance from the sinus floor to the sinus roof pre and post operatively was 0.30 mm (±0.10 SE) in the study group and 1.30 mm (±0.27 SE) in the control group (P = .0221). The mean change in the distance from the bone crest to the sinus floor was 0.32 mm (±0.09 SE) in the study group and 1.26 mm (±0.28 SE) in the control group (P = .0019), and the mean change in the sinus sagittal circumference was 37.34 mm (±6.10 SE) and 125.95 mm (±15.60 SE), respectively (P = .0001). CONCLUSIONS Ridge preservation using bovine derived xenograft might reduce sinus pneumatization along with minimizing crestal bone resorption.

The association between dental proximal restorations and periodontal disease: A retrospective 10-18 years longitudinal study.

OBJECTIVE Dental restorations may be plaque retentive. The aim of this study was to evaluate the long-term association between proximal restorations and the incidence and progression of periodontal disease in well-maintained patients. METHOD AND MATERIALS Probing pocket depths (PPD), bleeding on probing (BOP), and radiographic status of proximal restorations were retrospectively retrieved from files of patients attending a specialist periodontal office. Ill-fitting margins were recorded. The association between these parameters was evaluated at baseline examination (T0), after cause-related therapy (T1) and after ≥ 10 years from T0 (T2), during which supportive periodontal therapy (SPT) was administered, using descriptive statistics, ANOVA-Bonferroni, and chi-square analyses. RESULTS 1,301 teeth were examined. Mean PPD in unrestored surfaces was 3.7 ± 1.7 mm, 3.1 ± 1.3 mm, and 2.8 ± 1 mm at T0, T1, and T2, respectively. Deeper pockets were found in restored surfaces at those time points with PPD values of 4.4 ± 1.8 mm, 3.6 ± 1.4 mm, and 3.2 ± 1.1 mm, respectively (P < .001). Higher PPD values were found in restored surfaces exhibiting inadequate restorations when compared to restored surfaces with adequate restorations at all time points. These values were 4.9 ± 1.9 mm, 4.1 ± 1.5 mm, and 4 ± 1.7 mm vs 4.3 ± 1.8 mm, 3.6 ± 1.4 mm, and 3.1 ± 1.1 mm, respectively (P < .001). CONCLUSION The present study confirmed that restorations might be detrimental to periodontal health. A significant association between the presence of proximal restorations and the incidence of periodontal disease was observed. This association was more pronounced for inadequate restorations while becoming less significant over time in patients receiving routine SPT.

The association between shallow vestibular depth and peri‐implant parameters: a retrospective 6 years longitudinal study

AIM The aim of this study was to retrospectively evaluate the association between shallow vestibular depth (VD) and peri-implant parameters. MATERIAL AND METHODS Peri-implant parameters were evaluated in 61 periodontal patients under regular supportive periodontal therapy. Clinical parameters included gingival index (GI), plaque index (PI), bleeding on probing (BOP), peri-implant pocket depths (PPD), mucosal recession (MR), relative attachment level (RAL), width and thickness of keratinized mucosa (KMW, KMT) and VD. Radiographic bone level (RBL) was measured on peri-apical radiographs. RESULTS Sites with shallow VD (≤ 4 mm) were associated with higher MR (0.91 mm versus 0.47 mm, p ≤ 0.009), higher RAL (4.23 mm versus 3.59 mm, p ≤ 0.0001) and higher RBL (2.18 mm versus 1.7 mm, p = 0.05) when compared with adequate vestibular depth sites (VD > 4 mm). Moreover, sites with shallow VD presented lower KMW compared with sites with adequate VD (1.24 mm versus 2.38 mm, respectively, p ≤ 0.0001). Slightly greater BOP, and GI were recorded for the shallow VD compared with adequate sites. According to multivariate analysis, factors that could predict RAL included: VD, GI, age, supporting periodontal therapy, implant type and design. CONCLUSIONS Based on this study, inadequate vestibular depth around dental implants may be associated with increased peri-implant bone loss and mucosal recession. Further prospective and intervention studies will be required to fully understand this phenomenon.

Improving the Mechanical Rigidity of Hyaluronic Acid by Integration of a Supramolecular Peptide Matrix

Hyaluronic acid (HA), a major component of the extracellular matrix, is an attractive material for various medical applications. Yet, its low mechanical rigidity and fast in vivo degradation hinder its utilization. Here, we demonstrate the reinforcement of HA by its integration with a low-molecular-weight peptide hydrogelator to produce a composite hydrogel. The formulation of HA with the fluorenylmethoxycarbonyl diphenylalanine (FmocFF) peptide, one of the most studied self-assembling hydrogel-forming building blocks, showing notable mechanical properties, resulted in the formation of stable, homogeneous hydrogels. Electron microscopy analysis demonstrated a uniform distribution of the two matrices in the composite forms. The composite hydrogels showed improved mechanical properties and stability to enzymatic degradation while maintaining their biocompatibility. Moreover, the storage modulus of the FmocFF/HA composite hydrogels reached up to 25 kPa. The composite hydrogels allowed sustained release of curcumin, a hydrophobic polyphenol showing antioxidant, anti-inflammatory, and antitumor activities. Importantly, the rate of curcumin release was modulated as a function of the concentration of the FmocFF peptide within the hydrogel matrix. This work provides a new approach for conferring mechanical rigidity and stability to HA without the need of cross-linking, thus potentially facilitating its utilization in different clinical applications, such as sustained drug release.

Advantages of Self-assembled Supramolecular Polymers Toward Biological Applications

Supramolecular self-assembly provides a means of achieving “bottom-up” fabrication of nanoscale materials. Their mechanical properties and functionality arise from the assembly of relatively simple molecular building blocks. These materials have selective affinity to different interfaces, high capacity for interfacial adsorption, nanostructure, and spontaneous formation of unique nano-self-assemblies which exhibit remarkable simplicity and biocompatibility. Due to these attractive features, supramolecular nanostructures, particularly peptide-based, have recently been explored as effective nanomaterials in applications ranging from controlled release and drug delivery, nano-fabrication, skin care, biomineralization, sensing, antimicrobial materials, and tissue engineering. This range of applications is facilitated by the diverse primary sequences of the short peptides, which can be either biomimetic or de novo designed. Thus, their self-assembling mechanistic processes and nanostructures also vary enormously. This chapter highlights recent advances in studying self-assembled peptide systems, focusing on the formation of different nanostructures and their applications in diverse fields.