Mediterranean diet component oleic acid increases protective lipid mediators and improves trabecular bone in a Porphyromonas gingivalis inoculation model.

AIM: Therapeutic modulation of bacterial-induced inflammatory host response is being investigated in gingival inflammation and periodontal disease pathology. Therefore, dietary intake of the monounsaturated fatty acid (FA) oleic acid (OA (C18:1)), which is the main component of Mediterranean-style diets, and saturated FA palmitic acid (PA (C16:0)), which is a component of Western-style diets, was investigated for their modifying potential in an oral inoculation model of Porphyromonas gingivalis. MATERIALS AND METHODS: Normal-weight C57BL/6-mice received OA- or PA-enriched diets (PA-ED, OA-ED, PA/OA-ED) or normal standard diet for 16 weeks and were inoculated with P. gingivalis/placebo (n = 12/group). Gingival inflammation, alveolar bone structure, circulating lipid mediators, and in vitro cellular response were determined. RESULTS: FA treatment of P. gingivalis-lipopolysaccharide-incubated gingival fibroblasts (GFbs) modified inflammatory activation, which only PA exacerbated with concomitant TNF-α stimulation. Mice exhibited no signs of acute inflammation in gingiva or serum and no inoculation- or nutrition-associated changes of the crestal alveolar bone. However, following P. gingivalis inoculation, OA-ED improved oral trabecular bone micro-architecture and enhanced circulating pro-resolving mediators resolvin D4 (RvD4) and 4-hydroxydocosahexaenoic acid (4-HDHA), whereas PA-ED did not. In vitro experiments demonstrated significantly improved differentiation in RvD4- and 4-HDHA-treated primary osteoblast cultures and reduced the expression of osteoclastogenic factors in GF. Further, P. gingivalis infection of OA-ED animals led to a serum composition that suppressed osteoclastic differentiation in vitro. CONCLUSIONS: Our results underline the preventive impact of Mediterranean-style OA-EDs by indicating their pro-resolving nature beyond anti-inflammatory properties.

Autoclaving-induced dimensional changes of three-dimensional printed surgical guides: An in vitro study.

OBJECTIVES: Surgical guides are frequently used for dental implant placement. The aim of this study was to evaluate the impact of the 3D printing process itself and subsequent steam autoclaving on the dimensional stability of five different resin/printer combinations (RPCs). MATERIALS AND METHODS: Fifty identical surgical guides (10 per group) were produced consisting of five RPCs. Half of the guides (5 per group) were steam autoclaved with cycle 1 (121°C, 1 bar, 20.5 min) and the other half with cycle 2 (134°C, 2 bar, 5.5 min). All guides were scanned with a structured-light (SL) 3D scanner before (T0) and after (T1) autoclaving. Linear measurements along the x-, y-, and z-axes were performed at landmarks on the original STL file and on SL scans at T0 and T1, respectively. Wilcoxon signed-rank test, Kruskal-Wallis test, and linear mixed-effects models were performed, depending on the analysis. RESULTS: Three-dimensional printing was associated with significant dimensional alterations for all RPCs. Steam autoclaving using cycle 1 was associated with significant shrinkage in x- (1 RPC), y- (2 RPCs), and z-direction (2 RPCs), while cycle 2 was also associated with shrinkage in x- (2 RPCs), y- (1 RPC), and z-direction (1 RPC). One resin did not present any dimensional changes independently of the cycle. CONCLUSIONS: The majority of the guides presented minor but significant shrinkage due to 3D printing itself and both steam autoclaving cycles, the extent varied between different RPCs. Whether these changes compromise implant placement accuracy remains to be investigated.

Micro-angiogenic patterns around orthodontic implants migrating in bone: A micro-CT study in the rat tail model.

AIM: Recent studies revealed that implants can migrate in bone when subjected to continuous loading. Since this process is suspected to be accompanied by bone remodelling, which requires blood vessel formation, the present work aimed at assessing the micro-angiogenic patterns around migrating implants. MATERIALS AND METHODS: In 16 rats, two customized implants were placed in a single tail vertebra and connected with contraction springs (forces: 0 N, 0.5 N, 1.0 N, 1.5 N). After 2 or 8 weeks of loading, the animals were scanned by micro-CT before and after vasculature perfusion with a silicone rubber. Vessels were segmented by subtraction of the two micro-CT scans. Vessel thickness (V.Th), vessel volume per total volume (VV/TV), and vascular spacing (V.Sp) were assessed in a peri-implant volume of interest (VOI) around each implant. RESULTS: At 2 weeks of loading, force magnitude was significantly associated with VV/TV and V.Th values (χ2  = 10.942, p < .001 and χ2  = 6.028, p = .010, respectively). No significant differences were observed after 8 weeks of loading. CONCLUSIONS: Within the limitations of an animal study, peri-implant vessel thickness and density were associated with force magnitude in the early loading phase, whereas effects diminished after 8 weeks of loading.

Bone remodelling patterns around orthodontic mini-implants migrating in bone: an experimental study in rat vertebrae.

BACKGROUND: Orthodontic implant migration has been clinically observed in presence of continuous loading forces. Recent studies indicate that osteocytes play a crucial role in this phenomenon. OBJECTIVES: Aim of this study was to investigate local osteocytic gene expression, protein expression, and bone micro-structure in peri-implant regions of pressure and tension. MATERIAL AND METHODS: The present work reports a complementary analysis to a previous micro-computed tomography study. Two customized mini-implants were placed in one caudal rat vertebra and connected by a nickel-titanium contraction spring generating different forces (i.e. 0, 0.5, 1.0, and 1.5 N). Either at 2 or 8 weeks, the vertebrae were harvested and utilized for 1. osteocytic gene expression using laser capture micro-dissection on frozen sections coupled with qPCR, 2. haematoxylin-eosin staining for qualitative and quantitative analyses, 3. immunofluorescence staining and analysis, and 4. bone-to-implant contact on undecalcified samples. RESULTS: At the two time points for all the performed analyses no significant differences were observed with respect to the applied force magnitudes and cell harvesting localization. However, descriptive histological analysis revealed remarkable bone remodelling at 2 weeks of loading. At 8 weeks the implants were osseointegrated and, especially in 1.0 and 1.5 N groups, newly formed bone presented a characteristic load bearing architecture with trabecula oriented in the direction of the loading. CONCLUSIONS: The present study confirmed that stress-induced bone remodelling is the biological mechanism of orthodontic implant migration. Bone apposition was found at 'tension' and 'pressure' sites thus limiting implant migration over time.

Eligibility of a novel BW + technology and comparison of sensitivity and specificity of different imaging methods for radiological caries detection.

OBJECTIVES: Bitewing radiography is considered to be of high diagnostic value in caries detection, but owing to projections, lesions may remain undetected. The novel bitewing plus (BW +) technology enables scrolling through radiographs in different directions and angles. The present study aimed at comparing BW + with other 2D and 3D imaging methods in terms of sensitivity, specificity, and user reliability. MATERIALS AND METHODS: Five human cadavers were used in this study. In three cadavers, natural teeth were transplanted post-mortem. BW + , two-dimensional (digital sensors, imaging plates, 2D and 3D bitewing radiographs) and 3D methods (high and low dose CBCT) were taken. Carious lesions were evaluated on 96 teeth at three positions (mesial, distal, and occlusal) and scored according to their level of demineralization by ten observers, resulting in 35,799 possible lesions across all observers and settings. For reference, µCT scans of all teeth were performed. RESULTS: Overall, radiographic evaluations showed a high rate of false-negative diagnoses, with around 70% of lesions remaining undetected, especially enamel lesions. BW + showed the highest sensitivity for dentinal caries and had comparatively high specificity overall. CONCLUSIONS: Within the limits of the study, BW + showed great potential for added diagnostic value, especially for dentinal caries. However, the tradeoff of diagnostic benefit and radiation exposure must be considered according to each patient's age and risk.

Microstructural volumetric analysis of vertical alveolar ridge augmentation using autogenous tooth roots.

BACKGROUND: To volumetrically assess the bone microstructure following vertical alveolar ridge augmentation using differently conditioned autogenous tooth roots (TR) and second-stage implant placement. MATERIALS AND METHODS: The upper premolars were bilaterally extracted in n = 4 beagle dogs and randomly assigned to either autoclavation (TR-A) or no additional treatment (TR-C). Subsequently, TR were used as block grafts for vertical alveolar ridge augmentation in both lower quadrants. At 12 weeks, titanium implants were inserted and left to heal 3 weeks. Microcomputed tomography was used to quantify bone volume per tissue volume (BV/TV), trabecular thickness (Tb.Th), and trabecular spacing (Tb.Sp) at vestibular (v) and oral (o) aspects along the implant and in the augmented upper half of the implant, respectively. RESULTS: Median BV/TV [TR-C: 51.33% (v) and 70.42% (o) vs TR-A: 44.05% (v) and 64.46% (o)], Tb.th [TR-C: 0.22 mm (v) and 0.27 mm (o) vs TR-A: 0.23 mm (v) and 0.29 mm (o)] and Tb.Sp [TR-C: 0.26 mm (v) and 0.13 mm (o) vs TR-A: 0.29 µm (v) and 0.15 mm (o)] values were comparable in both groups. CONCLUSION: Both TR-C and TR-A grafts were associated with a comparable bone microstructure within the grafted area.