Intraspecific variation in M1 enamel development in modern humans: implications for human evolution

The timing and sequence of enamel development, as well as enamel thickness, was documented for individual cusps (protoconid, hypoconid,metaconid, entoconid) in 15 unworn permanent lower first molars (M1s) from a sample of modern human juveniles. These data were compared with previously published data for modern and fossil species reported in the literature. Crown formation in all teeth was initiated in the protoconid and completed in the hypoconid. These cusps had significantly longer formation times (2.91 and 2.96 yrs, respectively) than the metaconid and entoconid (2.52 and 2.38 yrs, respectively), as well as thicker enamel, and each represented between 92e95% of the total crown formation time. Rates of enamel secretion in all cusps increased significantly from 2.97 mm in the inner enamel to 4.47 mm in the outer enamel. Two cusps of one individual were studied in more detail and did not follow this typical trajectory. Rather, there was a sharp decrease in the middle of enamel formation and then a slow recovery of secretion rates from the mid to outer enamel. This anomalous trajectory of enamel formation is discussed in the context of other nondental tissue responses to illness. Neither secretion rates nor periodicity differed significantly when compared between the cusps of each molar. Differences in cusp formation times, initiation, and completion suggest a relationship between the rates of enamel formation and enamel thickness. This fits with expectations about the mechanics of the chewing cycle and general lower molar morphology. A comparison with similar data for some nonhuman primates and fossil hominoids suggests this relationship may hold true across several primate taxa. Other aspects of enamel growth differed between this human sample and certain fossil species. The lower molars formed slowly over a longer period of time, which may reflect the extended growth period of modern humans. The methodological approach adopted in this study is discussed in the context of that used in other studies

Collagenous bone matrix-induced endochondral ossification hemopoiesis.

Transplantation of collagenous matrix from the rat diaphyseal bone to subcutaneous sites resulted in new bone formation by an endochondral sequence. Functional bone marrow develops within the newly formed ossicle. On day 1, the implanted matrix was a discrete conglomerate with fibrin clot and polymorphonuclear leukocytes. By day 3, the leukocytes disappeared, and this event was followed by migration and close apposition of fibroblast cell surface to the collagenous matrix. This initial matrix-membrane interaction culminated in differentiation of fibroblasts to chondroblasts and osteoblasts. The calcification of the hypertrophied chondrocytes and new bone formation were correlated with increased alkaline phosphatase activity and 45Ca incorporation. The ingrowth of capillaries on day 9 resulted in chondrolysis and osteogenesis. Further remodelling of bony trabeculae by osteoclasts resulted in an ossicle of cancellous bone. This was followed by emergence of extravascular islands of hemocytoblasts and their differentiation into functional bone marrow with erythropoietic and granulopoietic elements and megakaryocytes in the ossicle. The onset and maintenance of erythropoiesis in the induced bone marrow were monitored by 59Fe incorporation into protein-bound heme. These findings imply a role for extracellular collagenous matrix in cell differentiation

Impact of Delayed Completion of Previously Initiated Therapy and Provider Type on Outcomes of Root Canal Treatment

Objective:if the provider type influences long-term outcomes in instances where NSRCT has been previously initiated. The primary purpose of this study was to determine if the period of time between previously initiated therapy and the completion of non-surgical root canal treatment (NSRCT) influences long-term outcomes. The secondary purpose of this study was to determineMaterials/Methods: Enrollment and claims data from Delta Dental of Wisconsin from2002-2014 was analyzed. Teeth that received NSRCT within 6 months after completionof pulpal debridement or pulpotomy procedures (identified by Codes of DentalProcedures and Nomenclature) and within a continuous insurance coverage period wereincluded. Teeth that did not receive definitive restorations within 180 days followingcompletion of NSRCT were excluded. Teeth were followed from the time of treatment tothe presence of a CDT code representing untoward events, which include retreatment,apicoectomy, or extraction. The impact of tooth location, age at time of NSRCTcompletion, and provider type on the outcome was also examined using Univariate andMultivariable Cox proportional hazards models. A total of 7,488 NSRCTs were includedin the analysis. Results:. Molar teeth were associated with a greater risk of an untoward event than anterior teeth with an adjusted hazard ratio of1.52 (p\u3c0.029). An increase in the risk of failure was observed in teeth from patients that were 55 and older with an adjusted hazard ratio 2.15 (p\u3c0.001). A significantly lower adjusted hazard ratio of 0.68 (p\u3c0.001) was observed when treatment was initiated by a general dentist and completed by an endodontist when compared to treatment that was both initiated and completed by a general dentist.Conclusion: Delayed completion of NSRCT after previously initiated therapy was not associated with unfavorable outcomes.No statistically significant difference was found among the varying time intervals between initiation and completion of NSRCT Improved outcomes were noted when previously

The association between Ponticulus Posticus and Dental Agenesis: a retrospective study

OBJECTIVE: Neural tube defects may increase the risk of an abnormal development of skull, vertebral column and teeth formation, including dental agenesis in non syndromic patients. The association between the presence of a congenital Dental Agenesis (DA) and the Atlantooccipital Ligament (AOL) calcification, known as "Ponticulus Posticus" (PP), as possible links can be investigated. DESIGN: After a systematic review of the scientific literature on this topic, two independent examiners assessed the AOL calcification in lateral cephalograms of 350 non syndromic patients(7-21 years old). The results were compared with a control group (non syndromic patients, without congenital missing teeth). RESULTS: The 16.3% of the population studied by cephalometric analysis revealed a prevalence rate of PP (both complete and partial) with a slight male predominance is seen, not statistically significant (χ square test = 0.09; p= 0.76). In both sexes complete PP is more observed. In the patients affected by DA the frequency of PP is the 66.6% (both complete than partial). The χ square test with Yates correction showed a significative difference(χ= 66.20; p value= 0.00) between PP in patients with DA compared to not affected by DA. CONCLUSIONS: PP is not an uncommon anomaly. Since orofacial pain like migraine and other symptoms are often associated to PP, during routine radiographic examination, if detected, it should be documented in patients' health record and with symptoms, further investigation should be sought for. These findings encourage to think there's an association between DA in non syndromic patients and neuro-crestal cells defects

Usporedba dentalne i skeletne dobi kod hrvatskih ispitanika

This study investigated the relationships between the stages of calcification of teeth and cervical vertebral maturation. The sample consisted of 295 subjects (129 male and 166 female), mean age 13.36±2.65 (range 7-18) years. Dental age was evaluated from panoramic radiographs according to the method of Demirjian. Cervical vertebral maturation was determined on lateral cephalometric radiographs using cervical vertebrae maturation stages (CVS). For assessing the relationship between cervical vertebral and dental maturation, percentage distributions of the stages of calcification for each studied tooth were calculated. Only in the first CVS stage, boys and girls were of the same age. In all other stages (CVS 2- CVS 6) girls were by 0.98 (range 0.23-1.86) younger than boys. Gender differences in the mineralization pattern were also observed. It was found that dental maturation was finished earlier in female subjects. The highest correlation coefficient between dental and skeletal maturity was found for second premolars. Mineralization pattern of second premolars could be considered as a guideline for prediction of the pubertal growth spurt. Dental maturation stages might be clinically useful as a reliable indicator of facial growth.Cilj ovoga istraživanja bio je odrediti odnos između stupnjeva mineralizacije zuba i stupnjeva skeletne zrelosti. Uzorak se sastojao od 295 ispitanika (129 muških i 166 ženskih). Srednja dob za uzorak je bila 13.36±2.65 (raspon 7-18) godina. Dentalna zrelost je određena metodom ortopantomograma prema Demirjianu. Skeletna zrelost vratne kralježnice određena je na laterolateralnim snimkama glave pomoću stupnjeva maturacije vratne kralježnice (cervical vertebrae maturation stages, CVS). Za određivanje odnosa između stupnjeva maturacije vratne kralježnice i zuba izračunata je postotna distribucija stupnjeva mineralizacije za svaki zub. Samo u prvom stupnju CVS dječaci i djevojčice su bili iste kronološke dobi. U svim ostalim stupnjevima (CVS 2-CVS 6) djevojčice su bile 0,98 (raspon 0,23-1,86) mlađe od dječaka. Pronađene su spolne razlike u dobu mineralizacije, naime, mineralizacija zuba završava ranije kod ženskih ispitanika. Najveći stupanj korelacije između dentalne i skeletne dobi pronađen je kod drugih premolara. Vrijeme mineralizacije drugih premolara moglo bi pomoći u predviđanju maksimalnog zamaha pubertalnog rasta. Stupnjevi dentalne zrelosti mogli bi biti pokazatelj kraniofacijalnog rasta

Establishing a diagnostic tool for assessing optimal treatment timing in Indian children with developing malocclusions

Objective: To interrelate chronological age, cervical vertebrae maturational stage and dental calcification stages and to establish latter as first level diagnostic tool to estimate timing of pubertal growth spurt. Materials and Methods: Sample derived from pretreatment panaromic and lateral cephalometric radiographs of patients 8-14 years old. Study sample divided into three groups depending upon Angle’s molar relation: Group I, Group II, Group III. According to chronological age, into: Group A: 8-11 years Group B:11-14 years, further separating males and female subjects in each group. Demirjian et al method was used to assess dental maturity and for skeletal maturity the New Improved Version of Cervical Vertebrae Maturation Method by Baccetti, Franchi and Mc Namara. Statistical analysis was performed using SPSS software package. Chi Square test and Spearman rank-order correlation coefficients measured the association between skeletal maturity indicators and dental calcification stages and statistical significance tested. Results&Conclusions: In females, permanent mandibular second molar Stage E signified circumpubertal phase corresponding with skeletal age CVMS II and for males, it was permanent mandibular first premolar stage E. Early orthodontic interventions for Angle’s Class I and Class II malocclusions should be performed at the circumpubertal period represented by CVMS II in Indian children and for Angle’s Class III malocclusion, facemask therapy beneficial in the prepubertal phase. Females showed higher significant correlation among skeletal and dental calcification stages compared to males

Age determination and age related factors in the teeth of Western North Atlantic bottlenose dolphins.

Teeth were taken from 120 bottlenose dolphins, Tursiops truncatus, which had stranded on the mid-Atlantic coast of the United States. The number of annual growth layer groups (GLGs) for each animal was used to construct a growth curve. The growth rate of coastal North Atlantic Ocean Tursiops is similar to other cetaceans in having a high initial rate of growth, with no differences in growth between females and males. In females, the first dentinal GLG is thickest and is followed by GLGs which become progressively narrower. In males, the second GLG is thicker than the first; GLGs beyond number two become progressively smaller but at a slower rate than in females. In males and females, the translucent layer makes up proportionally larger parts of the GLG as the animal ages, but in males the percent translucent layer remains constant at about 50% while in females it continues to increase up to about 70% of the GLG. These two factors, GLGs width and translucent layer width, indicate that the sex and age of the animal influence the deposition of GLGs. Incremental layers are also present, averaging 12 per GLG, and seem similar to incremental layers described in other marine mammals. A plot of the relationship of percent growth of the last GLG to time of death suggests that the deposition of GLGs is relatively constant, at least during the first half of the year, and that North Atlantic Ocean Tursiops give birth in the fall as well as in the spring. (PDF contains 31 pages.

SNX10 gene mutation leading to osteopetrosis with dysfunctional osteoclasts

Acknowledgements We sincerely thank the patients and family members who participated in this study. We would also like to thank Stefan Esher, Umeå University, for help with genealogy, and Anna Westerlund for excellent technical assistance. This work was supported by grants from the FOU, at the Umeå university hospital, and the Medical Faculty at Umeå University. The work at University of Gothenburg was supported by grants from The Swedish Research Council, the Swedish Rheumatism Association, the Royal 80-Year Fund of King Gustav V, ALF/LUA research grant from Sahlgrenska University Hospital in Gothenburg and the Lundberg Foundation. The work at the University of Gothenburg and the University of Aberdeen was supported by Euroclast, a Marie Curie FP7-People-2013-ITN: # 607446.Peer reviewedPublisher PD

Radiocarbon analysis of modern skeletal remains to determine year of birth and death: a case study

To aid in the development of a biological profile for human remains found in Collyhurst, Manchester, England we undertook 14C analysis of tooth enamel, tooth collagen and bone collagen on behalf of Greater Manchester Police. On the basis of the analyses of the teeth, we concluded that the person was born between 1950 and 1954 while on the basis of our analyses of cortical and trabecular bone we estimated the year of death to be between 1969 and 1974. This would make the maximum age range around 15 to 24 years. Analyses of the dentition and other skeletal parameters can eliminate the younger part of the range so an age of around 18 to 24 years at death would seem most likely. The δ13C and δ15N values for the bone collagen were higher than would be expected for someone subsisting on a purely terrestrial diet, implying some consumption of marine resources which could lead to reduced 14C activities. Taking any potential marine effect into account could reduce this age range to around 18 to 21 years

Marine Flora and Fauna of the Northeastern United States: Erect Bryozoa

Forty-nine species of erect Bryozoa from a broad range of Cyclostome, Ctenostome, and Cheilostome families are described and illustrated, and an artificial dichotomous key is provided for their identification. In general, the marine bryozoan faunas of the northeastern coasts of the United States are poorly known; species records are sparse and voucher collections few, and it is certain that many more species occur in this region than are presently known. The species described here occur in intertidal, coastal or offshore habitats; some are well known and have been recorded on numerous previous occasions, others have been only rarely reported, while a few are known to occur commonly in the north of the region but have yet to be recorded south of Cape Cod. Some of the species described have not been recorded at all on northeastern coasts of the United States, but are widely distributed in North Atlantic continental shelf habitats and perhaps occur in similar parts of the outer shelf of this region. This fauna is thus provisional, but is intended to stimulate further work on the Bryozoa. (PDF file contains 52 pages.