Hypersementose og endodontiske implikasjoner

Hypersementose er forbundet med lokale og systemiske faktorer, men etiologien er ikke godt kartlagt. Vanskeligheter med å bedømme røntgenologisk tykkelse på sementlaget ved hypersementose, vil direkte kunne påvirke beslutning om renselengde og apikalavstand. Endodontisk behandling av hele kanalens lengde blir dermed utfordret. Tenner med hypersementose viser seg å ha varierende grad av forsnevringer i kanalsystemet, apikale resorpsjoner, samt irregulariteter og kompliserte forgreninger i apikalområdet. Rotsementen er også utsatt for bakteriell vekst på grunn av et omfattende nettverk av lakuner, og tenner med hypersementose kan derfor være mer resistente mot endodontisk behandling. Det er lite tilgjengelig informasjon om forekomst av endodontisk sykdom og behandlingsresultat på tenner med hypersementose. Denne artikkelen gir en oversikt over temaet hypersementose, og belyser endodontiske problemstillinger knyttet til dette.publishedVersio

Mekanisk rens med et resikrokerende endodontisk filsystem. En laboratoriestudie

Målsettingen med denne studien var å finne ut hvor godt et standardisert resiprokerende filsystem instrumenterer i den apikale delen av rotkanalen i forskjellige tanngrupper. Tretti ekstraherte incisiver, premolarer og molarer ble benyttet. Hver tann ble først instrumentert med WaveOne Gold® og deretter ble det skåret en skive med snittflater tilsvarende 1 og 2 mm fra apeks. Prosent instrumentert areal av totalt kanalareal og instrumentert kanalvegg av total kanalomkrets ble vurdert på 1 og 2 mm-nivå. I tillegg ble filstørrelse som ville gitt en sirkulær kanal beregnet. Instrumentering med filsystemet vil ofte etterlate uinstrumenterte områder i rotkanalen, og i liten grad gi en sirkulær standardisert preparering i den apikale delen av kanalene.publishedVersio

Systemic Chemical Desensitization of Peptidergic Sensory Neurons with Resiniferatoxin Inhibits Experimental Periodontitis

Background and objective: The immune system is an important player in the pathophysiology of periodontitis. The brain controls immune responses via neural and hormonal pathways, and brain-neuro-endocrine dysregulation may be a central determinant for pathogenesis. Our current knowledge also emphasizes the central role of sensory nerves. In line with this, we wanted to investigate how desensitization of peptidergic sensory neurons influences the progression of ligatureinduced periodontitis, and, furthermore, how selected cytokine and stress hormone responses to Gram-negative bacterial lipopolysaccharide (LPS) stimulation are affected. Material and methods: Resiniferatoxin (RTX; 50 μg/kg) or vehicle was injected subcutaneously on days 1, 2, and 3 in stress high responding and periodontitis-susceptible Fischer 344 rats. Periodontitis was induced 2 days thereafter. Progression of the disease was assessed after the ligatures had been in place for 20 days. Two h before decapitation all rats received LPS (150 μg/kg i.p.) to induce a robust immune and stress response. Results: Desensitization with RTX significantly reduced bone loss as measured by digital X-rays. LPS provoked a significantly higher increase in serum levels of the pro-inflammatory cytokine tumour necrosis factor (TNF)-, but lower serum levels of the anti-inflammatory cytokine interleukin (IL)-10 and the stress hormone corticosterone. Conclusions: In this model RTX-induced chemical desensitization of sensory peptidergic neurons attenuated ligatureinduced periodontitis and promoted a shift towards stronger pro-inflammatory cytokine and weaker stress hormone responses to LPS. The results may partly be explained by the attenuated transmission of immuno-inflammatory signals to the brain. In turn, this may weaken the anti-inflammatory brain-derived pathways

Conditioned media from hypoxic-cultured human dental pulp cells promotes bone healing during distraction osteogenesis

Distraction osteogenesis (DO) is a surgical procedure used to correct various skeletal disorders. Improving the technique by reducing the healing time would be of clinical relevance. The aim of this study was to determine the angiogenic and regenerative potential of conditioned media (CMs) collected from human dental pulp cells (hDPCs) grown under different culture conditions. CM collected from cells under hypoxia was used to improve bone healing and the DO procedure in vivo. The angiogenic potentials of CMs collected from hDPCs grown under normoxic (−Nor) and hypoxic (−Hyp) conditions were evaluated by quantitative PCR (VEGF-A, angiopoietin-1, angiopoietin-2, interleukin-6 (IL-6) and CXCL12), ELISA assays (VEGF-A, Ang-2), tube-formation and wound-healing assays, using human umbilical vein endothelial cells. The results demonstrated that hypoxic CM had significantly higher angiogenic potential than normoxic CM. Human fetal osteoblasts (hFOBs) were exposed to CM, followed by alizarin red staining, to assess the osteogenic potential. It was found that CM did not enhance the mineralization capacity of hFOBs. DO was performed in the tibiae of 30 mice, followed by a local injection of 20 µl CM (CM–Nor and CM–Hyp groups) or serum-free DMEM (control group) into the distraction zone every second day. The mice were sacrificed at days 13 and 27. The CM–Hyp treatment revealed a higher X-ray density than the control group (p < 0.05). Our study suggests that the angiogenic effect promoted by hypoxic culture conditions is dependent on VEGF-A and Ang-2 released from hDPCs. Furthermore, CM–Hyp treatment may thus improve the DO procedure, accelerating bone healing. © 2015 The Authors. Journal of Tissue Engineering and Regenerative Medicine published by John Wiley & Sons, Ltd.publishedVersio

Osteogenic stimulatory conditions enhance growth and maturation of endothelial cell microvascular networks in culture with mesenchymal stem cells

To optimize culture conditions for in vitro prevascularization of tissue-engineered bone constructs, the development of organotypic blood vessels under osteogenic stimulatory conditions (OM) was investigated. Coculture of endothelial cells and mesenchymal stem cells was used to assess proangiogenic effects of mesenchymal stem cells on endothelial cells. Four different culture conditions were evaluated for their effect on development of microvascular endothelial cell networks. Mineralization, deposition of extracellular matrix, and perivascular gene expression were studied in OM. After 3 days, endothelial cells established elongated capillary-like networks, and upregulated expression of vascular markers was seen. After 15 days, all parameters evaluated were significantly increased for cultures in OM. Mature networks developed in OM presented lumens enveloped by basement membrane-like collagen IV, with obvious mineralization and upregulated perivascular gene expression from mesenchymal stem cells. Our results suggest osteogenic stimulatory conditions to be appropriate for in vitro development of vascularized bone implants for tissue engineering

Mesenchymal stem cells induce endothelial cell quiescence and promote capillary formation

Introduction: Rapid establishment of functional blood vessels is a prerequisite for successful tissue engineering. During vascular development, endothelial cells (ECs) and perivascular cells assemble into a complex regulating proliferation of ECs, vessel diameter and production of extracellular matrix proteins. The aim of this study was to evaluate the ability of mesenchymal stem cells (MSCs) to establish an endothelial-perivascular complex in tissue-engineered constructs comprising ECs and MSCs. Methods: Primary human ECs and MSCs were seeded onto poly(L-lactide-co-1,5-dioxepan-2-one) (poly(LLA-co-DXO)) scaffolds and grown in dynamic culture before subcutaneous implantation in immunocompromised mice for 1 and 3 weeks. Cellular activity, angiogenic stimulation and vascular assembly in cell/scaffold constructs seeded with ECs or ECs/MSCs in a 5:1 ratio was monitored with real-time RT-PCR, ELISA and immunohistochemical microscopy analysis. Results: A quiescent phenotype of ECs was generated, by adding MSCs to the culture system. Decreased proliferation of ECs, in addition to up-regulation of selected markers for vascular maturation was demonstrated. Baseline expression of VEGFa was higher for MSCs compared with EC (P <0.001), with subsequent up-regulated VEGFa-expression for EC/MSC constructs before (P <0.05) and after implantation (P <0.01). Furthermore, an inflammatory response with CD11b + cells was generated from implantation of human cells. At the end of the 3 week experimental period, a higher vascular density was shown for both cellular constructs compared with empty control scaffolds (P <0.01), with the highest density of capillaries being generated in constructs comprising both ECs and MSCs. Conclusions: Induction of a quiescent phenotype of ECs associated with vascular maturation can be achieved by co-seeding with MSCs. Hence, MSCs can be appropriate perivascular cells for tissue-engineered constructs

Comparison of bone regenerative capacity of donor-matched human adipose–derived and bone marrow mesenchymal stem cells

Adipose-derived stem cells (ASC) have been used as an alternative to bone marrow mesenchymal stem cells (BMSC) for bone tissue engineering. However, the efficacy of ASC in bone regeneration in comparison with BMSC remains debatable, since inconsistent results have been reported. Comparing ASC with BMSC obtained from different individuals might contribute to this inconsistency in results. Therefore, this study aimed to compare the bone regenerative capacity of donor-matched human ASC and BMSC seeded onto poly(L-lactide-co-ε-caprolactone) scaffolds using calvarial bone defects in nude rats. First, donor-matched ASC and BMSC were seeded onto the co-polymer scaffolds to evaluate their in vitro osteogenic differentiation. Seeded scaffolds and scaffolds without cells (control) were then implanted in calvarial defects in nude rats. The expression of osteogenesis-related genes was examined after 4 weeks. Cellular activity was investigated after 4 and 12 weeks. Bone formation was evaluated radiographically and histologically after 4, 12, and 24 weeks. In vitro, ASC and BMSC demonstrated mineralization. However, BMSC showed higher alkaline phosphatase activity than ASC. In vivo, human osteogenesis–related genes Runx2 and collagen type I were expressed in defects with scaffold/cells. Defects with scaffold/BMSC had higher cellular activity than defects with scaffold/ASC. Moreover, bone formation in defects with scaffold/BMSC was greater than in defects with scaffold/ASC, especially at the early time-point. These results suggest that although ASC have the potential to regenerate bone, the rate of bone regeneration with ASC may be slower than with BMSC. Accordingly, BMSC are more suitable for bone regenerative applications.publishedVersio

Hypersementose og endodontiske implikasjoner

Hypersementose er forbundet med lokale og systemiske faktorer, men etiologien er ikke godt kartlagt. Vanskeligheter med å bedømme røntgenologisk tykkelse på sementlaget ved hypersementose, vil direkte kunne påvirke beslutning om renselengde og apikalavstand. Endodontisk behandling av hele kanalens lengde blir dermed utfordret. Tenner med hypersementose viser seg å ha varierende grad av forsnevringer i kanalsystemet, apikale resorpsjoner, samt irregulariteter og kompliserte forgreninger i apikalområdet. Rotsementen er også utsatt for bakteriell vekst på grunn av et omfattende nettverk av lakuner, og tenner med hypersementose kan derfor være mer resistente mot endodontisk behandling. Det er lite tilgjengelig informasjon om forekomst av endodontisk sykdom og behandlingsresultat på tenner med hypersementose. Denne artikkelen gir en oversikt over temaet hypersementose, og belyser endodontiske problemstillinger knyttet til dette

Hammaspulpan biologiaa

Tiivistelmä Karieksen aiheuttamat komplikaatiot, hampaan voimakas kuluminen tai muu ulkoinen ärsytys voivat johtaa hammasytimen eli pulpan oireiseen tai oireettomaan inflammaatioon, jota seuraa pulpakudoksen osittainen tai etenevä hajoaminen ja kuolio. Sairaan pulpan asianmukaisella hoidolla pyritään säilyttämään hampaan vitaliteetti joko täydellisesti tai osittain, ja tällaista hoitoa voidaan siten pitää ”ehkäisevänä endodontiana”. Dentiini-pulpakompleksin fysiologian ja patologian ymmärtäminen on oikean diagnoosin ja näin ollen oikean hoidon edellytys. Tässä katsauksessa kuvataan terveen pulpan perusrakenne ja fysiologia. Lisäksi käydään läpi tulehdusreaktioiden käynnistymisen ja etenemisen periaatteita pulpakavumissa ja juurikanavissa, jotka ovat tulehdusprosessin kannalta joustamaton ympäristö. Tämän ohella käsitellään kivun ja hypersensitiivisyyden mekanismeja sekä keinoja, joilla dentiini-pulpakompleksi voi reagoida toistuvaan tai persistoivaan, kipua aiheuttavaan ärsytykseen. Pulpan tulehduksen hoitomuodot voivat vaihdella karieksen ekskavoinnista ja kaviteetin sulkemisesta sekä osittaisesta tai täydellisestä pulpotomiasta aina endodonttiseen hoitoon, ja niitä pohditaan tarkemmin tämän teeman muissa artikkeleissa, jotka käsittelevät diagnostiikkaa, vitaalin pulpan hoitoa ja kiireellistä hoitoa.Abstract Pulp Biology Pulpal complications of caries, extensive wear or other external irritations may result in symptomatic or asymptomatic inflammation, followed by partial or progressing pulp tissue degradation and necrosis. Appropriate treatment of diseased pulp may aim to preserve the vitality of the pulp, either completely or partially, and can thus be regarded as “preventive endodontics”. Understanding of the physiology and pathology of dentin-pulp complex is a prerequisite for the proper diagnosis and is thus the correct choice of treatment. This review describes the basic structure and physiology of a healthy dental pulp and the principles of the initiation and progression of inflammatory reactions in the low-compliance environment of the pulp chamber and root canals. The mechanisms of the pain and hypersensitivity, as well as the means that the dentin-pulp complex may react to a repeated or persistent pain-producing irritation, are also discussed. The chosen treatment modalities may vary from caries excavation and cavity sealing, partial or complete pulpotomy to an endodontic treatment, and will be discussed in detail in other articles in this issue dealing with the diagnostics, vital pulp therapies and emergency treatments

Influence of bone marrow stromal cell secreted molecules on pulpal and periodontal healing in replanted immature rat molars

Aim. To investigate the effect of paracrine factors secreted from human bone marrow stromal cell (BMSC-CM) on pulpal and periodontal healing following immediate replantation of maxillary rat first molars. Material and Methods. Fifty maxillary rat first molars were elevated and replanted after 2 min. The left teeth were replanted without treatment, whereas BMSC-CM was injected into the right socket prior to replantation. Twelve un-operated teeth served as reference teeth. The expression of vascular endothelial growth factor A, alkaline phosphatase, Runt-related transcription factor 2 and osteoclast stimulating factor 1 was studied by real-time reverse transcription polymerase chain reaction at day 3 and 14. The dentin thickness together with Laminin- and PGP 9.5-immunoreactivity were studied after 3, 14 and 90 days. Results. Real-Time qRT-PCR data showed up-regulated expression of ALP mRNA in the socket specimens of conditioned medium treated replanted teeth after 3 days. No morphological differences were found for the expression of Laminin and PGP 9.5 between control and conditioned medium treated replanted teeth. At day 14, external cervical and surface root resorption was found in one BMSC-CM and one control tooth. At 90 days, all control replanted teeth had external cervical and surface root resorptions, whereas only one sample was seen among the conditioned medium treated teeth. At day 90, more extensive dentine formation with narrowing of the pulpal space was observed in the control compared with conditioned medium treated teeth. Conclusions. The present findings showed that BMSC-CM treatment reduced the number of replanted teeth with external root resorption and resulted in a significant reduction in new dentin formation