Root Lengthening Research Articles

Renaissance of the tooth fairy!!!

Regenerative endodontic procedures have brought novelty in the arena of dentistry. Stem cell research has paved its way into conserving and utilizing the multipotent stem cells for tissue growth. One such procedure is revascularization which utilizes the apical stem cells for root lengthening and reinforcement in traumatized tooth with an open apex. The present clinical case report has shown that revascularization results in successful root lengthening and apical closure in lesser appointments than conventional specification procedure without weakening the dentinal walls.

감염된 미성숙 영구치에서 platelet-rich fibrin과 double antibiotic paste를 이용한 치수 재혈관화 : 증례 보고

Paradigm shift in management of infected immature permanent teeth has occurred. The new concept of the treatment includes minimal or no intracanal instrumentation, disinfection with triple antibiotic paste and sealing with mineral trioxide aggregate. This regenerative endodontic treatment promotes differentiation of periradicular stem cells that induce regeneration of vital tissue and continuation of root formation. Thorough disinfection and three-dimensional scaffold are important in this new concept of the treatment. Platelet-rich fibrin has been reported as 'new scaffold' instead of blood clot, which had been used in the past. Triple antibiotics can be used to disinfect the tooth but may lead to complications including discoloration. Three cases of infected immature permanent tooth caused by dens evaginatus fracture are presented. After removal of necrotic pulp and thorough intracanal irrigation, only platelet-rich fibrin was applied to the root canal in the first case. In the other cases, topical antibiotics was used for disinfection and platelet-rich fibrin for scaffold. In all the cases, the opening was sealed with mineral trioxide aggregate. All the cases showed proper healing of inrabony lesion and some lengthening of root. According to these cases, regenerating vital tissue of the infected immature permanent tooth can be achieved with disinfection and application of platelet-rich fibrin.

Revascularization of an immature tooth with a necrotic pulp using platelet‐rich fibrin: a case report

To discuss the clinical and radiological outcome of a revascularization procedure in an immature tooth with a necrotic pulp using platelet-rich fibrin (PRF), a second-generation platelet concentrate. A 7-year-old male reported with pain in the maxillary anterior region as a result of the injury to his immature right maxillary central incisor tooth. After preparation of the access cavity, the necrotic pulp was removed and the canal irrigated using 5.25% sodium hypochlorite solution. The canal was then dried and packed with triantibiotic paste for 3weeks. After removal of the antibiotic paste, a 5mL sample of whole venous blood was drawn from the patient's forearm to prepare PRF. The freshly prepared PRF was condensed in the canal until the cementoenamel junction. Three millimetres of white MTA was placed directly over the PRF clot. Three days later, the tooth was restored using a permanent restoration. At 7-, 12- and 15-month recall, the tooth was asymptomatic with no sensitivity to percussion or palpation. At 12- and 15-month follow-up, the tooth responded positively to cold and an electric pulp test, and similarly to adjacent lateral incisor and canine teeth. Radiographic examination demonstrated continued thickening of root canal walls, root lengthening and apical closure. Platelet-rich fibrin might serve as a potentially ideal scaffold in revascularization of immature permanent teeth with necrotic pulps as it is rich in growth factors, enhances cellular proliferation and differentiation, and acts as a matrix for tissue ingrowth.

Revascularization with and without Platelet-rich Plasma in Nonvital, Immature, Anterior Teeth: A Pilot Clinical Study

IntroductionThis study was conducted to evaluate and compare maturogenesis induced by revascularization with and without platelet-rich plasma (PRP). MethodsTwenty patients with nonvital, immature anterior teeth were randomly categorized into 2 groups. Subsequent to chemomechanical preparation, revascularization with and without PRP carried on a collagen sponge was induced in groups 1 and 2, respectively. The cases were followed up clinically and radiographically at 6- and 12-month intervals. ResultsClinically, all cases were asymptomatic with complete resolution of signs and symptoms. Radiographically, there was a marked difference in periapical healing, apical closure, and dentinal wall thickening in group 2 in comparison with group 1. However, root lengthening was comparable for both of the procedures. ConclusionsRevascularization is a conservative and an effective method for inducing maturogenesis in nonvital, immature teeth. Supplementations with PRP can potentially improve the desired biological outcome of this regenerative technique.

Platelet Rich Fibrin in the revitalization of tooth with necrotic pulp and open apex

Regeneration of pulp-dentin complex in an infected necrotic tooth with an open apex is possible if the canal is effectively disinfected. The purpose of this case report is to add a regenerative endodontic case to the existing literature about using Platelet Rich Fibrin (PRF). A nine year old boy who accidently broke his immature maxillary central incisor tooth, developed pulpal necrosis with apical periodontitis. After the access cavity preparation, the canal was effectively irrigated with 20 ml of 5.25% sodium hypochlorite solution and 10ml of 0.2% chlorhexidine solution and dried with paper points. Triple antibiotic paste was placed inside the canal and left for 21 days. 12 ml of whole blood was drawn from the patient's right antecubital vein and centrifuged for 10 minutes to obtain the Choukroun's PRF. After the removal of the triple antibiotic paste, the PRF was placed into the canal till the level of cementoenamel junction and 3mm of grey MTA was placed directly over the PRF clot. The setting of MTA was confirmed 3 days later and the tooth was double sealed with GIC and Composite restoration. After 1 year the clinical examination revealed negative responses to percussion and palpation tests. The tooth responded positively to cold and electric pulp tests. Radiographic examination revealed continued thickening of the dentinal walls, root lengthening, regression of the periapical lesion and apical closure. On the basis of the results obtained in our case report we conclude that revitalization of necrotic infected immature tooth is possible under conditions of total canal disinfection and PRF is an ideal biomaterial for pulp-dentin complex regeneration.

Lanthanum Element Induced Imbalance of Mineral Nutrients, HSP 70 Production and DNA-Protein Crosslink, Leading to Hormetic Response of Cell Cycle Progression in Root Tips ofVicia fabaL. Seedlings

The effects and mechanisms of rare earth elements on plant growth have not been extensively characterized. In the current study, Vicia faba L. seedlings were cultivated in lanthanum (La)-containing solutions for 10 days to investigate the possible effects and mechanisms of La on cell proliferation and root lengthening in roots. The results showed that increasing La levels resulted in abnormal calcium (Ca), Ferrum (Fe) or Potassium (K) contents in the roots. Flow cytometry analysis revealed G1/S and S/G2 arrests in response to La treatments in the root tips. Heat shock protein 70 (HSP 70) production showed a U-shaped dose response to increasing La levels. Consistent with its role in cell cycle regulation, HSP 70 fluctuated in parallel with the S-phase ratios and proliferation index. Furthermore, DNA-protein crosslinks (DPCs) enhanced at higher La concentrations, perhaps involved in blocking cell progression. Taken together, these data provide important insights into the hormetic effects and mechanisms of REE(s) on plant cell proliferation and growth.

Lanthanum Resulted in Unbalance of Nutrient Elements and Disturbance of Cell Proliferation Cycles in V. faba L. Seedlings

Effects of lanthanum (La) on mineral nutrients, cell cycles, and root lengthening have been little reported. The present work investigated these physiological responses in roots of Vicia faba seedlings cultivated in La3+-contained solutions for 15 days. The results showed that the increasing contents of La in the roots and leaves contributed to disbalances of contents of Ca, Fe, Cu, Zn, Mg, Mn, P, and K elements, and potential redistributions of some elements in the roots and leaves. These disbalances might be involved in the subsequent alteration of cell cycle phases in the root tips. Low-dose promotion and high-dose inhibition (Hormetic effects) were demonstrated as the dose responses of G0/G1-, S- or G2/M-phase ratios. The cell cycles were most probably arrested at G1/S interphase by La3+ in the root tips. The fact that the root lengths were not consistent with the changes of cell cycle phases suggested that the cell proliferation activities might be masked by other factors (e.g., cell expansion) under long-time exposure to La3+.

Effects of Acetylsalicylic Acid on Germination, Growth and Chlorophyll Amounts of Cucumber (Cucumis sativus L.) Seeds

Germination activities, various growth parameters (primary root length, hypocotyl length, primary leaf length, plant length and increase in fresh weight) and chlorophyll (a+b) amounts of cucumber seeds exposed to 0, 10(-5), 10(-4), 10(-3) and 0.5x 10(-2) M aqueous solutions of acetylsalicylic acid (ASA) for 48 h were established. While 0.5x 10(-2) M ASA significantly prevented germination activity of the seeds, other concentrations did not produce any effect, either positive or negative. Meanwhile, 0.5x 10(-2) M ASA inhibited radicle growth of the germinated seeds, while 10(-5) M ASA increased radicle growth. Other concentrations of ASA did not affect radicle growth. The following findings were obtained from the one-week seedlings exposed to ASA for 48 h: 0.5x10(-2) M ASA prevented growth (lengthening) of root, hypocotyl, leaf and plant and increased chlorophyll (a+b) amount with an increase in fresh weight. Contrary to 0.5x 10(-2) M ASA application, these features of the seedlings (except for the leaf length) were encouraged by 10(-5) M ASA. 10(-3)) M ASA only prevented root growth and reduced chlorophyll (a+b) amount. Other concentrations of ASA did not bring about any positive or negative effect on the features studied.

Effects of cadmium on meristem activity and nucleus ploidy in roots of Pisum sativum L. cv. Frisson seedlings

The effects of cadmium (Cd) administration on primary root growth, mitotic activity of apical meristems, mitotic aberrations and percentage of nucleus ploidy classes of differentiated roots were examined in Pisum sativum L. cv. Frisson. Cadmium caused a reduction of root length related to concentration, with an almost complete block of growth in plants treated with 250 μM Cd, from 24 h of treatment. Root lengthening is generally related to apical meristem activity, however, in the examined pea plants, mitotic activity was suppressed by 2.5 and 25 μM Cd treatment, while the highest Cd concentration, 250 μM, caused the occurrence of mitotic figures consisting almost exclusively of prophases. The lack of relation between root lengthening and mitotic activity was explained by the meristematic activity in the first period of treatment and by a different cell elongation. Lower (0.25, 0.5 and 1 μM), non-blocking Cd concentrations induced a number of mitotic aberrations, mainly consisting of sticky metaphases and anaphase bridges, whose frequency increased with Cd concentration. Besides, Cd induced variations of the percentages of nucleus populations in the differentiated roots, increasing the percentage of 4C nuclei and decreasing that of 2C. The mechanisms involved in the nuclear response to Cd, and the possible relations between Cd alteration of meristem cell activity and nuclear ploidy of differentiated cells are discussed.

Caryopsis dormancy, germination and seedling emergence in sand, of Leymus racemosus (Poaceae), a perennial sand-dune grass inhabiting the Junggar Basin of Xinjiang, China

Leymus racemosus (Lam.) Tzvel. (Poaceae), wild rye, is an endangered, but economically important, perennial grass. It is mainly distributed in the moving or semistabilised sand in deserts of the Junggar Basin in Xinjiang, China. Freshly harvested caryopses are in non-deep physiological dormancy, causing slow and low germination. Six weeks of cold stratification at 5�C is required for the highest germination percentage to be reached at 25–30�C. Scarifying the fruit coat, or artificial removal of different proportions of the endosperm, also increases caryopsis germination. The greater the proportion of the endosperm that was removed, the higher the percentage of germination reached. However, the dry weight of the seedlings and the rate of root and shoot lengthening were significantly influenced by the proportion of the endosperm that remained on the caryopses.The influences of caryopsis size, or of the proportion of remaining endosperm, on germination and seedling emergence from different depths in sand were studied. The percentage of germination was negatively influenced by burial depth, but not by caryopsis size or the proportion of the endosperm that remained. Seedling emergence was negatively related to both burial depth and caryopsis or endosperm sizes. Seedlings from the smallest seeds or from caryopses with 75% endosperm removed did not emerge from 4 cm, and no seedlings from any of the treatments emerged from a depth of 8 cm.

ROOT SYSTEMS CHARACTERISTICS OF MAIZE (Zea mays L.) AND POTATO (Solanum tuberosum L.) SEEDLINGS AND ITS RELATIONSHIP WITH THE PHOSPHATE FERTILIZER APPLICATION METHODS

During the days following germination, when the seed’s reserves run out and root growth is slow, stress may occur due to a deficit of phosphorus (P), which has repercussions in later development of the plant and its yield. Plant species differ in their ability to absorb P, and this depends on the amount of available P in the soil and the capacity of the root system to acquire it. The objective of this study was to compare, under controlled conditions, the absorption of P, the morphological (length, surface area, and density) and physiological (intensity of P absorption) root characteristics of maize seedlings (cv. Batan-92) and potato (cv. FL795) when phosphate fertilizer is applied locally. The soil used in the experiment was a sandy loam-textured Andisol. The treatments were P localized at 2, 5, and 8 cm to one side of the seed (L), below the seed at 2, 5, and 8 cm deep (Pr), incorporated (I), and a control without P. The amounts of P were 81 and 54 mg.kg-1, in function of the forms of application. The maize was harvested at 17 and 30 days after germination, and potato was harvested 34 days after germination. The growth behavior of the maize and potato roots treated with P localized in the different forms was not the same. Potato developed an average ratio of radical density in the fraction fertilized with P, compared to the rest of the soil, 2.2 times higher than maize, i.e. potato depends more on P applied as a fertilizer than maize. The accumulation of P and the production of dry matter in maize and potato were in function of the root characteristics and the availability of P in the soil. The total mean root density in maize was 2.7 times higher than in potato. To compensate the lower root density and rate of root lengthening, potato required more available P in the soil than maize and developed a greater intensity of absorption of this element [100 nmol.cm-1 (34 days) vs. 24 nmol.cm-1 (30 days), respectively].

Changes in root length during orthodontic treatment: advantages for immature teeth.

The purpose of the study was to investigate root lengthening during orthodontic treatment in relation to the age of the patient, the developmental stage of the root, and the anticipated growth. Specifically, the potential benefit of treating young teeth was addressed. The sample consisted of 80 patients with Angle Class II division 1 malocclusions, treated with extraction of at least two maxillary first premolars, and edgewise technique with 0.018-inch slot brackets. Additionally, a cross-sectional control group of 66 untreated individuals matched to gender, and pre- and post-treatment age of the experimental group was included. Crown and root lengths of the maxillary incisors were measured on peri-apical radiographs before and after treatment, and corrected for image distortion. The stage of root development before treatment was recorded. Root elongation during treatment was found for 50 out of the 280 examined teeth. Age at treatment start was significantly higher among the patients showing root shortening of the lateral incisors during treatment than among those showing root elongation (P < 0.05). The stage of root development was significantly related to the direction of root length change, i.e. shortening or elongation. Roots elongated during treatment did not differ in length from untreated teeth of similarly aged individuals. There was no significant difference in the extent of root lengthening between the roots elongated during treatment and the normal root lengthening in age-matched untreated individuals. Post-treatment root length was significantly related to pre-treatment age. Roots that were incompletely developed before treatment reached a significantly greater length than those that were fully developed at the start of treatment. The results of this study show a definite advantage for younger teeth with regard to post-treatment root length. This finding may influence treatment planning strategy.

Extraoral root lengthening with titanium screws

The aim of the present study was to experimentally evaluate marginal and periapical healing in extracted and subsequently replanted teeth following extraoral cementing of apically exposed titanium root screws in the root canal. In 5 out of 6 replanted teeth, the periodontal tissues had healed with a normal periodontal membrane or healed surface resorptions indicating that only minor trauma had been inflicted during the extraoral procedure. In 3 out of 6 teeth, total or partial osseointegration of the titanium screws was seen, while a connective tissue capsule had formed around the remaining 3 screws. It was concluded that both of the healing results described in the present study, osseointegration and connective capsule formation, may be regarded as acceptable as long as inflammation is prevented, although it remains to be shown which one represents the end-point.

A radiographic study of posterior apical root resorption in orthodontic patients

The purpose of this study was to determine the extent of apical root resorption, after fixed appliance therapy, in the posterior part of the dentition, and to evaluate if predisposing factors can be pointed out retrospectively. Tooth length in the posterior part of the dentition was measured on pretreatment and posttreatment orthopantomograms of 153 patients who were treated with standard edgewise appliances. Pretreatment and posttreatment tooth lengths were determined, and an attempt was made to explain the differences by sex, age, stage of root formation at onset of orthodontic treatment, extraction versus nonextraction therapy and treatment duration. Patients were divided into two groups according to their root formation. Group A consisted of patients with incompleted root formation at onset of orthodontic treatment except for the first molars. Group B consisted of patients where root formation was completed with the exception of second and third molars. Posttreatment tooth lengths of groups A and B were compared with pretreatment tooth lengths of group B with a paired t test, and correlations with the variables were calculated with multiple regression analysis only in group B. Posttreatment group A showed no significant differences with the mean root lengths of pretreatment group B. Differences between the mean pretreatment and posttreatment root lengths in group B were significant. Posterior teeth showed root shortening during active orthodontic treatment independent of sex, age, extraction versus nonextraction therapy, and duration of active treatment. Teeth with incompleted root formation at onset of orthodontic treatment showed root lengthening during active treatment, yet did not reach their "normal" tooth length.

Apexogenesis

The permanent teeth erupt while undergoing tooth formation and root lengthening. These immature teeth are more vulnerable to pulp exposure. Faced with the necessity for root canal treatment, and taking into account the unlikely possibility of successful obturation of an immature canal system, it is recommended that these developing teeth be treated by a biological approach. When the vital pulp of a tooth is exposed and the pulp is not irreversibly inflamed and apical development and closure is incomplete apexogenesis procedures are recommended. Vital pulp therapy techniques are described.

THE EFFECT OF CYTOKININS ON GROWTH and PIGMENT ACCUMULATION OF RADISH SEEDLINGS (RAPHANUS SATIVUS L.) GROWN IN THE DARK and AT DIFFERENT LIGHT QUANTA FLUENCE RATES*

Abstract— The dependency of cytokinin effects upon irradiance was studied with radish seedlings (Raphanus sativus L. cv. Saxa Treib). Kinetin (6‐furfurylamino‐purine) or BAP (6‐benzylamino‐purine) were applied via the roots of plants growing either in continuous darkness or under high (90 Wm‐2) or low intensity white light (10Wm‐2). Apart from the different development of plants at low and high fluence rates, the following cytokinin effects were found:(1) Both cytokinins acted in a similar manner on growth characteristics and pigment accumulation at high and low light conditions, BAP being in many cases more effective than kinetin.(2) When compared with the control, the cytokinins suppressed hypocotyl and root lengthening in the dark and light‐grown plants. In darkness they led to increased cotyledon areas, whereas in the light the leaf expansion was suppressed.(3) In the etiolated and low light grown plants, the anthocyanin content of the hypocotyls was enhanced due to the action of cytokinins, whereas under high light the anthocyanin accumulation was decreased.(4) In the cotyledons of etiolated plants, more phototransformable protochlorophyll(ide) and more carotenoids were formed when cytokinins were present. In green leaves the carotenoid content was diminished due to the action of cytokinins, particularly in plants grown in strong light. The chlorophyll a/b ratio was increased in the cytokinin‐treated plants in most cases.The results suggest a light dependency of the cytokinin effects. It is believed that the response of a plant towards exogenously applied cytokinins is similar to that with high intensity light.

Développement hivernal de semis de Douglas

The authors studied the winter behavior of Douglas-fir seedlings and the influence of a complete fertilization. Under normal climatological conditions, the seedlings showed a winter development increased by the addition of fertilizers.Among the several variations of aerial and underground parts of the vegetal, the growth of the root system is very important since a lengthening of the tap root and an increase in both the number of lateral roots, and total weight were observed.