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At least 1,387 records · Page 77Linked to original sources
PubMed2003

Palaeopathological and variant conditions of the Homo heidelbergensis type specimen (Mauer, Germany).

Although early Homo specimens are now known from a number of African, Asian and European Middle Pleistocene sites, the taxon Homo heidelbergensis was initially introduced for the Mauer jaw recovered in 1907. Fossil hominids from the earlier Middle Pleistocene of Europe are very rare and the Mauer mandible is generally accepted as one of the most ancient, with an age of approximately 700 kyr. A new preparation of the mandible was conducted in 1996 and gave rise to the detailed palaeopathological examination which is presented here. Based on comparative analyses, the extreme breadth of the mandibular ramus and its flat intercondylar incision, in conjunction with the flattening and broadening of the coronoid process tip, results either from an idiosyncratic pattern of the course and insertion of the temporalis muscle on the coronoid process or from the temporalis possessing an accessory head. The incidence of periodontal pocketing, together with a vertical reduction of the alveolar margin to approximately 3.00 mm, and a slight protuberance formed in vicinity of the right M(2)can safely be interpreted as pathognomonic indications of periodontal disease. The short distance between the enamel-dentine junction of the teeth and the horizontal alveolar margins could either be an inherited variant or may result from incipient osteoporosis. In addition, an arthrotic condition with slight osteophytic peripheral exostoses and an arthrolit (i.e. an articular calculus or "joint mouse") on the left condylus articularisand a depression in the medial part of the left mandibular condyle extending into the inferior part of the ramus are present. These features are indicative of a trauma-induced osteochondrosis dissecans. The diagnosis therefore suggests that the observed depression results from a well-healed fracture. This traumatic event illustrates the demanding living conditions endured by humans during the European Middle Pleistocene. The variations and pathological conditions observed in Mauer do not question the mandible's role as type specimen for the taxon Homo heidelbergensis.

Alveolar Process↗
PubMedDate not supplied

Effects of one versus two applications of an unfilled, all-in-one adhesive on dentine bonding.

OBJECTIVES: This study examined the null hypothesis that there is no difference between the effect of a one versus two-layer applications of Prompt L-Pop (3M ESPE, Seefeld, Germany) to sound, abraded human coronal dentine. METHODS: In group I, the mixed adhesive was applied for 15s, and light-cured for 10s. In group II, after light-curing the first layer, the adhesive was re-applied and light-cured. Specimens bonded with a hybrid composite were sectioned into beams for microtensile bond strength evaluation. Additional teeth from each group were bonded similarly using a lining composite for transmission electron microscopy examination of the resin-dentine interfaces, and nanoleakage evaluation using ammoniacal silver nitrate. RESULTS: A significant difference (p<0.001) was detected between microtensile bond strengths in the two groups. Stained, demineralized sections revealed 3-5 microm thick hybrid layers in both groups. An electron-lucent layer between 7 and 20 microm thick was present between the adhesive and the overlying composite. This layer was absent from the interfaces after removal with ethanol before composite placement. The use of a single application in group I resulted in the direct contact of the electron-lucent layer with the dentine surface and tubular orifices. In unstained, undemineralized sections used to evaluate nanoleakage, silver deposits were found mostly in the hybrid layer in group II, but throughout the entire adhesive layer in group I. CONCLUSION: Bonding of this unfilled all-in-one adhesive to dentine may be improved by application of a second adhesive layer after light-curing the first layer. This ensures that the exposed dentine surface and dentinal tubules are coated with adhesive that is adequately polymerized.

Composite Resins↗
PubMed1995

Craniofacial morphology, occlusal traits, and bite force in persons with advanced occlusal tooth wear.

The aim of this study was to investigate the dentofacial structure, the occlusal traits, and the bite force in subjects with advanced occlusal wear. The material comprised 54 adults, 30 men (mean = 40 years, range 16 to 61) and 24 women (mean = 28 years, range 18 to 47), most of whom had a full or near-full complement of natural teeth, and the presence of occlusal wear. Craniofacial structure was studied on lateral cephalograms. Occlusal traits were examined on study casts, these serving also for an evaluation of occlusal wear to be carried out by using an ordinal scale. Bite forces were recorded at differing force levels (maximum biting, "biting as when chewing" and "light biting") and occlusal positions. Although maximum bite force and endurance time did not differ significantly between men and women, the level of bite force was high compared with other samples. The craniofacial structure of the sample was characterized by a deviation in the vertical direction, a small angle between the mandibular-palatal planes and a small gonial angle, as compared with Swedish adult norms. No significant differences were found in anteroposterior relationships between persons with advanced wear and normal standards. The results support the hypothesis that functional hyperactivity of the masticatory system imposed increased stress on the bony structures of the craniofacial complex with possible influences on its structure.

Adolescent↗
PubMed1997

Three-dimensional measurement of enamel loss caused by bonding and debonding of orthodontic brackets.

A mechanical computerized three-dimensional scanner with a resolution of 1 micron was used to assess loss of enamel caused by orthodontic bonding and debonding. A total of 2646 measurements was performed on six human premolars. The results showed an average loss of enamel of 7.4 microns. The range was between 1 and 52 microns, which may account for discrepancies with earlier studies that measured only a few points per tooth surface.

Acid Etching, Dental↗
PubMed1997

A longitudinal study of tooth wear in orthodontically treated patients.

The primary objective of this study was to determine whether there is a relationship between incisal/occlusal tooth wear during the mixed dentition and subsequent wear of the adult dentition. Pretreatment orthodontic records taken during the mixed dentition (T1), as well as follow-up records taken an average of 20 years later (T2), were available for 223 orthodontically treated patients. Incisal/occlusal tooth wear was measured on a tooth-by-tooth basis from T1 and T2 stone casts with a four-category scoring system. Multiple regression analysis (R2 = 0.33) indicated that wear could be predicted at a given age during adulthood from wear observed on the deciduous mandibular canines and molars at T1 (p < 0.0001). This predictive relationship was modified by the age at which the T1 wear was observed (p = 0.029) and possibly by the sex of the patient (p = 0.10). These results indicate that adult tooth wear is not independent of the tooth wear that occurred as a child. Bruxism is suggested as a possible common etiologic mechanism that may account for the relationship between childhood and adult tooth wear.

Adolescent↗
PubMed1996

Spatial resolution in radiometric analysis of enamel loss. A pilot study.

This pilot study was undertaken to determine whether spatial resolution affects radiometric analyses aimed at detecting progressive enamel loss. Four teeth were weighed, attached to a positioning device, and evaluated with radiography. A 1 mm strip of enamel was removed from each tooth, and the teeth were weighted again and reexamined by radiography. This process was repeated five times until 1/2 mm of dentin was removed. The radiographs were digitized twice with 59 and 200 microns pixels at 8 bits, providing two series of images with the optical densities converted into 256 gray levels. Each series of images was adjusted for contrast variation. Regions of interest were drawn on the crowns, and cumulative percent histograms (CPHs) were calculated. Within a series of CPHs enamel reduction resulted in shifts in the CPHs that were directly proportional to the amount of enamel removed. CPH shifts associated with the smaller 59 microns pixels accounted for 68% of the variation in weights caused by enamel reduction, whereas the shifts associated with the larger 200 microns pixels accounted for 50%. The results indicate that pixel size does affect radiometric determinations of enamel reduction.

Dental Caries↗
PubMed1999

Sleep disorders and the dental patient: an overview.

This article is intended to briefly describe common sleep disorders of interest to the dental profession and to render general management guidelines. Topics include sleep-related bruxism, xerostomia, hypersalivation, gastroesophageal reflux, apnea, and the effect of orofacial pain on sleep quality. The term sleep-related is used instead of the term nocturnal because some of the activities described can occur with daytime sleep.

Bruxism↗