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PubMed2002

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.

Age Factors↗
PubMed2001

Transcriptional responses in the hemiparasitic plant Triphysaria versicolor to host plant signals.

Parasitic plants in the Scrophulariaceae use chemicals released by host plant roots to signal developmental processes critical for heterotrophy. Haustoria, parasitic plant structures that attach to and invade host roots, develop on roots of the hemiparasitic plant Triphysaria versicolor within a few hours of exposure to either maize (Zea mays) root exudate or purified haustoria-inducing factors. We prepared a normalized, subtractive cDNA library enriched for transcripts differentially abundant in T. versicolor root tips treated with the allelopathic quinone 2,6-dimethoxybenzoquinone (DMBQ). Northern analyses estimated that about 10% of the cDNAs represent transcripts strongly up-regulated in roots exposed to DMBQ. Northern and reverse northern analyses demonstrated that most DMBQ-responsive messages were similarly up-regulated in T. versicolor roots exposed to maize root exudates. From the cDNA sequences we assembled a unigene set of 137 distinct transcripts and assigned functions by homology comparisons. Many of the proteins encoded by the transcripts are predicted to function in quinone detoxification, whereas others are more likely associated with haustorium development. The identification of genes transcriptionally regulated by haustorium-inducing factors provides a framework for dissecting genetic pathways recruited by parasitic plants during the transition to heterotrophic growth.

Benzoquinones↗
PubMed1999

Interactive effects of selenium and mercury on the restoration potential of leaves of the medicinal plant, Portulaca oleracea Linn.

Leaves of Portulaca oleracea have the potential of regeneration, when grown in a distilled water medium. The two heavy metals, Se and Hg individually and in combination affected both shoot and root development. They completely arrested shoot development at all concentrations. However, they produced concentration-dependent changes in the development of roots, which ranged from their complete inhibition to variation in their initiation time, number and length. Leaf decay was initiated on day 46 in control leaves. Concentration-dependent changes were also observed in the time of initiation and magnitude of decay of leaves. The data indicates that Hg was more toxic than Se. The protective effect of Se against Hg toxicity was evident only at very low concentrations. With further increases in the concentration of both Se and Hg, the protective effect decreased and simultaneously the toxicity increased. Following the decay of leaves, a pink colour development was observed only on leaves exposed to Se. Microbial analysis of leaves showed the presence of Acinetobacter only in Se-exposed leaves. Acinetobacter was therefore considered as probably involved in the formation of elemental Se, which produced a pink colour.

Acinetobacter↗
PubMed2005

Apexogenesis of a symptomatic mandibular first permanent molar with calcium hydroxide pulpotomy.

Vital pulp therapy of immature, symptomatic permanent posterior teeth presents a challenge in pediatric endodontics. A case report is presented in which cervical pulpotomy with calcium hydroxide was performed on a cariously exposed mandibular first permanent molar. The patient was seen every 3 months for a total of 18 months for a clinical and radiographic follow up. During the follow-up period, root development, as evidenced by root lengthening, was observed. Apical closure was evident at the end of 19 months. As the root canals showed a tendency toward calcification, root canal treatment was carried out, followed by restoration of the tooth with a stainless-steel crown. The success of this single-visit apexogenesis procedure supports the contention that young pulp possesses remarkable reparative capacity, as well as resistance to bacterial infection due to greater vascularity, and that apexogenesis with calcium hydroxide apical closure pulpotomy can be attempted for continued root development of symptomatic, vital, permanent teeth.

Calcium Hydroxide↗
PubMed1991

Apexification with the use of calcium hydroxide: a clinical study.

The purpose of this study was to examine the type of root-end closure achieved with the apexification technique, in relation to age, sex and stage of root development. Data from 34 cases, in which apexification was performed, were analyzed. In all cases chemically pure powder Ca (OH)2 with anaesthetic solution was used. The age of 12 patients was between 27-40 years (1 male and 11 females) and of the other 22 was between 8-20 years (14 males and 8 females). Continuation of root development was achieved in 6 cases, continuation and bridge formation was revealed in three cases, bridge formation was seen in 21 cases and finally in 4 cases no root-end closure was noticed. From the above results it was evident that the bridge formation was the most common form of root-end closure. Statistical analysis revealed a strong correlation between the type of root-end closure and the stage of root development prior to apexification in relation to: a) sex and b) age. Thus the bridge formation was the most common type (87.5%) in the group of females. Also in the same sex group concerning the stage 4 of root development bridge formation was again the type of root-end closure (92.85%). Finally, it was found that in age group B (27-45-years-old), with stage 4 of root development, the bridge formation was the most common type of root-end closure (90%).

Adolescent↗
PubMed2003

Maturogenesis: is it a new concept?

The treatment of an undeveloped (immature) tooth with a carious exposure has been reported extensively in the literature. The main objective of treatment is to provide vital pulp therapy to allow continued development of root dentin in the hope that the root will attain full maturity. A case report is presented that illustrates root development (maturogenesis), not just closure of the apex (apexogenesis). A direct pulp cap was performed after a carious pulp exposure using calcium hydroxide with iodoform paste. The crown was restored with a glass ionomer/composite resin cement.

Calcium Hydroxide↗
PubMed1980

Relationship between the eruption of mandibular first permanent molar and growth changes of adjacent structures.

The relationship between the eruption of mandibular first permanent molar and growth changes of the adjacent structures was statistically investigated on 16 children during the active eruption of the tooth. Semiannual records of 45-degree oblique cephoalgrams and dental casts were used as materials. The factor analysis with orthogonal rotation was applied and the pattern of associations was revealed by the following six factors: Factor 1. Proximity factor. With larger mesiodistal tooth diameter, the tooth tends to be more mesially positioned. Factor 2. Eruption factor. The tooth erupts rapidly, nearing the distal surface of mandibular second deciduous molar more quickly and simultaneously widening the space posterior to the dental arch more rapidly. Factor 3. Root development factor. As the root develops faster, the interdental space tends to close more rapidly. Factor 4. Eruption rate factor. As the tooth nears the occlusal plane, the rate of eruptive movement decreases. Factor 5. Tooth uprighting factor. With more amount of space posterior to the dental arch, the subsequent uprighting of the long axis of the tooth can be expected. Factor 6. Tooth inclination factor. Inclination of the long axis of the tooth crown is relatively independent from the variables examined.

Cephalometry↗
PubMed1995

A pathway for lateral root formation in Arabidopsis thaliana.

In plants, the hormone indole-3-acetic acid (IAA) can initiate the developmental program for lateral root formation. We have isolated mutants that have permitted the dissection of this program into initiation and maturation of lateral roots. The alf1-1 mutation causes hyperproliferation of lateral roots, alf4-1 prevents initiation of lateral roots, and alf3-1 is defective in the maturation of lateral roots. The alf3-1 mutant can be rescued by IAA, whereas the alf4-1 mutant is not rescued. Our data suggest a model in which IAA is required for at least two steps in lateral root development: (1) to initiate cell division in the pericycle, and (2) to promote cell division and maintain cell viability in the developing lateral root.

Arabidopsis↗
PubMed2006

Root fracture of immature permanent incisors--a case report.

This 7-year-old girl experienced pain in her upper central incisors following a fall to the ground. Radiographic examination revealed immature upper central incisors with mid-root oblique and horizontal root fractures. Splinting was performed. When at 3 months, an electric pulp test was positive for both injured teeth, and after 5 months, the fracture lines had disappeared on the radiographs, the splint removed. After 2 years, clinical examination showed normal tooth color and position, with a positive response to the pulp test. Radiographs demonstrated continuous root development, although root canal narrowing was noted at the healed fracture sites.

Child↗
PubMed1996

Effect of in vivo iron supplementation on oxygen radical production by soybean roots.

Both total iron content and the in vitro rate of iron reduction were higher in roots grown in the presence of exogenously added iron (up to 500 microM) than in roots grown in absence of supplemented iron. In vivo generation of reactive O2 species by intact roots was assessed employing 2',7'-dichlorofluorescein diacetate oxidation to a fluorescent product. Roots developed in the presence of 500 microM Fe-EDTA, showed significantly increased fluorescence (64%), as compared to roots developed in absence of added iron, suggesting that iron supplementation led to oxidative stress in vivo. At the subcellular level, iron content and Fe-EDTA reduction rate were significantly increased in microsomes isolated from roots developed in the presence of exogenously added iron, as compared to microsomes from roots grown in the absence of iron. Microsomes from Fe supplemented plants exhibited a 51% increase in 2',7'-dichlorofluorescein diacetate oxidation rate, a 55% increase in superoxide anion generation, and a four-fold increase in hydroxyl radical production as compared to controls. Iron supplementation did not affect the activity of antioxidant enzymes or the content of total thiols, however alpha-tocopherol content was significantly decreased in the homogenates and the microsomes isolated from roots supplemented with iron, as compared with values in roots developed in absence of iron. These data suggest that in vivo iron supplementation increased oxygen radical generation.

Antioxidants↗
PubMed1999

Finite element analysis of anterior tooth root stresses developed during endodontic treatment.

Vertical tooth root fractures are diagnostically challenging, frustrating, and an increasingly common cause of failure of tooth restoration. These vertical root fractures have been associated with many causes, including the endodontic process itself. To investigate these endodontic causes, various phases of crown replacement for an anterior tooth were modeled using nonlinear, plane strain finite element (FE) analysis. Stresses developed during obturation, post positioning, crown placement, and masticatory and occlusal loading of the restored tooth were estimated using this analysis method. The minimum (compressive) principal stress was greatest during obturation of cones 1 and 2, and during mastication of the restored tooth. Although these stresses were significant (-150 to -280 MPa), they did not exceed the compressive strength of dentin. The maximum (tensile) principal stresses, 160 to 300 MPa, were also observed during obturation of cones 1 and 2. These peak stresses exceed the dentin tensile strength.

Crowns↗
PubMed2001

Auxin transport promotes Arabidopsis lateral root initiation.

Lateral root development in Arabidopsis provides a model for the study of hormonal signals that regulate postembryonic organogenesis in higher plants. Lateral roots originate from pairs of pericycle cells, in several cell files positioned opposite the xylem pole, that initiate a series of asymmetric, transverse divisions. The auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) arrests lateral root development by blocking the first transverse division(s). We investigated the basis of NPA action by using a cell-specific reporter to demonstrate that xylem pole pericycle cells retain their identity in the presence of the auxin transport inhibitor. However, NPA causes indoleacetic acid (IAA) to accumulate in the root apex while reducing levels in basal tissues critical for lateral root initiation. This pattern of IAA redistribution is consistent with NPA blocking basipetal IAA movement from the root tip. Characterization of lateral root development in the shoot meristemless1 mutant demonstrates that root basipetal and leaf acropetal auxin transport activities are required during the initiation and emergence phases, respectively, of lateral root development.

Arabidopsis↗
PubMed2002

Dental development of permanent lateral incisor in complete unilateral cleft lip and palate.

OBJECTIVE: The objective of this retrospective study was to verify whether the root development of the permanent lateral incisor on the cleft side was delayed, compared with its contralateral tooth in subjects with complete unilateral cleft lip and palate. SETTING: Craniofacial Anomalies Rehabilitation Hospital (HRAC)-University of São Paulo-Bauru, Brazil. PATIENTS: A sample of 98 panoramic radiographs of HRAC patients with complete unilateral cleft lip and palate was selected, regardless of sex and race. MAIN OUTCOME MEASURE: Panoramic radiographs were analyzed and the root development stage of the cleft-side permanent lateral incisor was compared with its contralateral tooth. RESULTS: Overall, the permanent cleft-side lateral incisor was significantly delayed in root development in relation to the non-left side contralateral tooth (p <.05). However, no significant differences were observed between boys and girls. CONCLUSIONS: Root development of the permanent cleft-side lateral incisor was delayed, compared with its contralateral tooth. The cleft itself may play an important role in this delay because the results from boys and girls were very similar.

Child↗
PubMed2005

Dental development of the permanent lateral incisor in patients with incomplete and complete unilateral cleft lip.

OBJECTIVE: This study aimed to evaluate a possible delay in root development of the permanent lateral incisor on the cleft side compared with its contralateral tooth in patients with incomplete and complete unilateral cleft lip. DESIGN: Retrospective. SETTING: Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo (HRAC/USP), Bauru, São Paulo, Brazil. PATIENTS: A sample of 95 panoramic radiographs of patients with incomplete and complete unilateral cleft was obtained from the files of HRAC/USP. The patients were both boys and girls of various races, aged 5 to 11 years, and did not have any syndrome or associated congenital malformation. The sample was divided into three groups according to the severity of the cleft lip. MAIN OUTCOME MEASURE: Radiographs were analyzed to compare root development stage of the lateral incisor on the cleft side with the noncleft side according to the classification of Nolla. RESULTS: The mean delay in root development of the permanent lateral incisor on the cleft side ranged from 0.5 to 1.6 scores for all three groups investigated. CONCLUSIONS: Root development of the permanent lateral incisor on the cleft side was delayed compared with the noncleft side.

Anodontia↗
PubMed2002

[Root system development ability of several alfalfa cultivars in the hilly and valley regions of Loess Plateau].

A field study was conducted in the hilly and valley regions of Loess Plateau in Gansu Province to analyze the root system development ability of several alfalfa (Medicago sativa) cultivars. Eight introduced cultivars and one local cultivar were arranged in the same site. The secondary roots of alfalfa cultivars grew mainly from the taproot underground 10-20 cm depth, and there were no secondary roots below 50 cm depth. The total amount of secondary roots of Sandili and Ameristand 201 was the biggest, and that of Longdong alfalfa was the lowest. The volume and biomass of different cultivars were decreased from 0-10 cm depth to below 50 cm depth, except those of Sandili and Ameristand 201 at 20-30 cm depth was bigger than at 10-20 cm depth. The biomass of Ameristand 201 was 170.54 g and bigger than that of others, and that of Longdong alfalfa, which was 22.4% of Ameristand 201, was the lowest. According to cluster analysis on 9 alfalfa cultivars, Sandili, Ameristand 201 and Amerigraze 401 were suitable for planting on the hills and valleys of Loess Plateau due to their root system development ability.

Biomass↗
PubMed1994

Clover development during spaceflight: a model system.

The development of legume root nodules was studied as a model system for the examination of gravitational effects on plant root development. In order to examine whether rhizobial association with clover roots can be achieved in microgravity, experiments were performed aboard the KC-135 parabolic aircraft and aboard the sounding rocket mission Consort 3. Binding of rhizobia to roots and the initial stages of root nodule development successfully occurred in microgravity. Seedling germination experiments were performed in the sliding block device, the Materials Dispersion Apparatus, aboard STS-37. When significant hydration of the seeds was achieved, normal rates of germination and seedling development were observed.

Cell Differentiation↗
PubMed2003

AXR3 and SHY2 interact to regulate root hair development.

Signal transduction of the plant hormone auxin centres on the regulation of the abundance of members of the Aux/IAA family of transcriptional regulators, of which there are 29 in Arabidopsis. Auxin can influence Aux/IAA abundance by promoting the transcription of Aux/IAA genes and by reducing the half-life of Aux/IAA proteins. Stabilising mutations, which render Aux/IAA proteins resistant to auxin-mediated degradation, confer a wide range of phenotypes consistent with disruptions in auxin response. Interestingly, similar mutations in different family members can confer opposite phenotypic effects. To understand the molecular basis for this functional specificity in the Aux/IAA family, we have studied a pair of Aux/IAAs, which have contrasting roles in root hair development. We have found that stabilising mutations in AXR3/IAA17 blocks root hair initiation and elongation, whereas similar mutations in SHY2/IAA3 result in early initiation of root hair development and prolonged hair elongation, giving longer root hairs. The phenotypes resulting from double mutant combinations, the transient induction of expression of the proteins, and the pattern of transcription of the cognate genes suggest that root hair initiation is controlled by the relative abundance of SHY2 and AXR3 in a cell. These results suggest a general model for auxin signalling in which the modulation of the relative abundance of different Aux/IAA proteins can determine which down-stream responses are induced.

Arabidopsis↗