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PubMedDate not supplied

The mandibular speech envelope in subjects with and without incisal tooth wear.

PURPOSE: The purpose of this study was to describe a mandibular envelope of motion during speech for 2 subject groups. One subject group had experienced no tooth wear and the other had incisal tooth wear. The speech envelope was to be described with regard to its maximal dimensions in the vertical, anteroposterior, and lateral directions, and its most superior and anterior positions in relation to intercuspal position. MATERIALS AND METHODS: An electromagnetic method of jaw tracking was employed to record mandibular speech movements for 60 subjects whose teeth exhibited no tooth wear and 30 subjects with incisal dental attrition. The test speech exercise contained all of the word sounds that occur in the English language. The test was recorded 3 times, and mean values for parameters were reported. RESULTS: The speech envelope of the tooth wear group was significantly smaller (Student's t test, P < 0.01) in all 3 dimensions than that of the normal group. The tooth wear group speech envelope was also located closer to the intercuspal position in the vertical dimension (P < 0.01) and was not as anteriorly placed (P < 0.01). In the normal group, correlations were found between the vertical incisor overlap and the most superior speech position (r = 0.48, P < 0.0001), and between the horizontal incisor overlap and the most anterior mandibular speaking position (r = 0.63, P < 0.0001). CONCLUSION: The envelope of mandibular movement during speech differed in dimension and position between the 2 groups investigated.

Adult↗

PubMed2000

The genetics of human tooth agenesis: new discoveries for understanding dental anomalies.

The important role of genetics has been increasingly recognized in recent years with respect to the understanding of dental anomalies, such as tooth agenesis. The lack of any real insight into the cause of this condition has led us to use a human molecular genetics approach to identify the genes perturbing normal dental development. We are reporting a strategy that can be applied to investigate the underlying cause of human tooth agenesis. Starting with a single large family presenting a clearly recognizable and well-defined form of tooth agenesis, we have identified a defective gene that affects the formation of second premolars and third molars. With the use of "the family study" method, evidence is produced showing that other genetic defects also contribute to the wide range of phenotypic variability of tooth agenesis. Identification of genetic mutations in families with tooth agenesis or other dental anomalies will enable preclinical diagnosis and permit improved orthodontic treatment.

Anodontia↗

PubMed2001

Mutans streptococci--in families and on tooth sites. Studies on the distribution, acquisition and persistence using DNA fingerprinting.

Mutans streptococci (MS) are bacteria showing several cariogenic traits. This thesis is based on the concept that humans acquire MS directly or indirectly from each other. Previous research on the transmission of the bacteria in families has indicated that children acquire MS from their mothers. Just a few studies have included fathers. Diverging results have been presented about spouses acquiring MS from each other. The information on the distribution of MS types at a tooth surface level has been limited. The methods used for identification of MS types have been refined during the years making further studies in the field interesting. The present thesis deals primarily with the distribution of MS in families. Twenty-five Swedish families including a 3-year-old first-born child (I) and 11 corresponding Chinese families (II) were studied. The Swedish families were followed up 2-5 years later (III and IV). Study V deals with the colonization of MS on tooth sites in 13 young adults. MS were isolated from bacterial plaque samples obtained from the teeth of the subjects. Identification of MS types was carried out through DNA analysis methods, REA and RAPD respectively. MS were detected in 11 of the 25 Swedish children. The distribution of MS genotypes in these families indicated that the mothers and individuals outside the family were the sources of MS to the children (I). The distribution of MS genotypes in the Chinese families (II) pointed to the fact that the father played a more pronounced role as MS source compared to in the Swedish families. The intra-familial distribution of MS seemed to be different in the two groups of families with different cultural backgrounds. At the follow-up, genotypes of MS were found again among the MS positive children and their parents. This indicated that genotypes of MS persisted. Even though some alterations in the prevalence of MS genotypes were shown (III). Among the MS negative children some had acquired the bacteria, but most of them remained MS negative by the age of 5-8 years (IV). The father was in some few cases the MS source to the child in the Swedish families (III, IV). Few spouses acquired MS from each other. It is not clear to which extent the parents' salivary levels of MS, caregiver of the child, breast-feeding or antibiotic treatment influenced the acquisition of MS in the groups studied (I-IV). Finally it was shown that several different genotypes of MS colonized a particular tooth site simultaneously. Within each individual the same genotype occurred on two or more tooth sites. Genotypes persisted 4-7 months on their site. The colonization diverged inter-individually in terms of the number and the distribution of MS genotypes on the tooth sites (V).

Adult↗

PubMed2002

[Tooth extraction in irradiated areas].

Tooth avulsion after head and neck radiotherapy has always been and is still a risk gesture when the avulsion is situated on the irradiation sites. The post-operating effects can become complicated with a delay in healing which can eventually induce an osteoradionecrosis. Dental treatment before the begining of radiotherapy aiming at the elimination of any suspicious tooth, and the generalisation of fluorotherapy aiming at limiting the decayed degeneration, did not make the avulsion indication disappear. At present tooth avulsion is still possible in case of tooth infection or broken tooth.

Collagen Type II↗

PubMed1998

Postmenopausal estrogen replacement and tooth retention.

Loss of underlying supportive alveolar bone is a major cause of tooth loss. Alveolar bone loss appears to be related to the status of the extracranial skeleton, and therapies that preserve skeletal bone may be expected to benefit tooth retention. An association between postmenopausal hormone replacement therapy (HRT) and tooth retention was found in a cohort of 488 elderly women, 72 to 95 years old, who participated in the Framingham Heart Study between 1948 and 1995. There was an association between duration of HRT and tooth retention for total number of teeth remaining and the individual types of teeth (incisors, canines, and premolars, but not molars) retained. The odds of being edentulous were reduced by 6% for each 1-year increase in duration of HRT use. The data suggest that postmenopausal HRT protects against tooth loss and reduces the risk of edentulism.

Age Factors↗

PubMed2002

Influence of environmental factors on tooth displacement.

An analysis of static occlusion including occlusal force and occlusal contact area in intercuspal position may be helpful but a dynamic analysis of occlusion should be regarded as more important for analyzing the stomatognathic system. Anthropological research has shown that the Japanese and the Mongolian populations share morphological and genetic similarities, although their dietary lives are not the same. The purpose of this study was to evaluate the relationship between environmental factors such as dietary life and stomatognathic function with a dynamic analysis of physiological tooth displacement. Ten clinically healthy subjects were recruited (mean age 24.8 +/- 1.0 years). The subjects were divided into two groups 1) Mongolian group: five Mongolians grown with a more or less natural texture diet and 2) Japanese group: five Japanese grown with a relatively soft diet. The displacement of the upper left first molar was measured during function using a three-dimensional tooth displacement transducer Type M-3. The tooth displacement in the Japanese group occurred mostly in an apicopalatal direction, but intruded basically parallel to the tooth axis in the Mongolian group. The stress-strain curve revealed that elastic socket deformation and viscous elements were more pronounced in the Japanese group. It was concluded that environmental factors such as dietary life could influence tooth displacement during function.

Adult↗

PubMed2002

Laboratory evaluations of elmex inter X toothbrushes for interproximal access efficacy and posterior tooth surface cleaning.

Laboratory methods have been developed to evaluate the ability of toothbrush bristles to remove artificial plaque deposits at interproximal sites (Interproximal Access Efficacy; IAE) and on distal tooth surfaces (Posterior Tooth Surface Cleaning; PTSC). In the testing performed for this study, six toothbrushes were evaluated. These were: elmex inter X Sensitive; elmex inter X Sensitive Short Head; elmex inter X medium; elmex inter X Medium Short Head; Oral-B Cross Action 40 medium; and the ADA reference standard toothbrush. Six toothbrushes of each design were tested four times under wet brushing conditions in all assays. In the IAE studies, toothbrushing was conducted using a vertical or horizontal brushing motion, simulated anterior or posterior teeth, and a brushing weight of 250 g. The bristles were placed at a 90 degree angle to the tooth surface, and brushing was performed for 15 seconds at two strokes per second with 50 mm strokes. IAE was recorded as the maximum width of simulated plaque deposit removed. For the PTSC evaluations, a horizontal brushing motion was used on posterior tooth shapes, with a 250 g brushing pressure for ten seconds. PTSC was determined as the maximum measurement of artificial plaque deposit removed from the mid-facial area to the maximum post-distal area of the most posterior simulated tooth shape. All data were assessed with ANOVA and the post hoc Tukey test. In the individual IAE tests, with vertical or horizontal brushing on anterior and posterior simulated teeth, and on overall IAE mean values, the four elmex inter X toothbrushes were significantly higher (p < 0.01-0.001) than the ADA reference standard and the Oral-B Cross Action 40 toothbrushes. The mean PTSC values for all toothbrushes were significantly higher (p < 0.01-0.001) compared to the ADA Reference Standard toothbrush mean PTSC. All elmex inter X brushes were statistically significantly higher (p < 0.01-0.001) compared to the Oral-B Cross Action 40 product. The elmex inter X Medium had a significantly higher (p < 0.05-0.001) PTSC compared to the PTSC mean values of the other elmex inter X products tested.

Analysis of Variance↗

PubMed2002

The influence of cervical lesion on the stress state and strength of tooth with occlusal restoration: a numerical model study.

This paper is concerned with bio-engineering problems in dentistry. The analysis of stress in a lower premolar with a deep non-carious cervical lesion and restored occlusal Class I cavity under occlusal load of 100 N was shown. Finite element method was used for the analysis of a two-dimensional model of a human tooth. In order to facilitate the evaluation of the loads, four cross-sections in characteristical points of the model were made. The model was generated and the calculations were done on IBM Pentium III personal computer. The principal and equivalent stresses were calculated and used in qualitative and quantative evaluation of tooth tissue and tooth restoration strength. The results are shown in figures and charts. The analysis of the cross-sections distant to the cervical area has proved that the presence or absence of cervical lesion has no significant influence on the values and stress distribution. Only in the region of sharp-shaped notch in the bottom of defect (4-4) high stresses in the tooth tissues occur. The values of stress did not exceed the compressive and tensile strength in any case under investigation. The study has shown that the presence of cervical angular lesion does not affect the mechanical strength of a tooth with a properly restored occlusal cavity. Clinically, the situation is safe from the biomechanical point of view.

Biomechanical Phenomena↗

PubMed2003

Evaluation of success rates of immediate and delayed implants after tooth extraction.

OBJECTIVE: To evaluate the success rates of immediate and delayed placement of implants with respect to the causes of tooth extraction and implant positions. METHODS: A total of 310 dental implants (immediate implants:delayed implants = 76:234) were inserted into 80 patients. The types, sizes and positions of the implants and the causes of tooth extraction were recorded. We then investigated the relationship of implant loss with the causes of tooth extraction and placement methods. RESULTS: A higher failure rate was found for the implants in the posterior region of the maxilla, and when periodontitis was cited as a reason for tooth extraction. The overall success rates were 93.4% and 95.7% in the immediate and delayed implant placement groups, respectively, after a 2-year follow-up. No obvious relationship of success rate was observed with the implant placement method, cause of tooth extraction, and implants' position. CONCLUSION: The immediate placement of implants into fresh extraction sockets could offer advantages over the delayed implant placement. It seems to be a safe and predictable method for patients.

Adolescent↗

PubMedDate not supplied

Does tooth wear status predict ongoing sleep bruxism in 30-year-old Japanese subjects?

PURPOSE: This study investigated whether tooth wear status can predict bruxism level. MATERIALS AND METHODS: Sixteen Japanese subjects (eight bruxers and eight age- and gender-matched controls; mean age 30 years) participated in this study. From dental casts of these subjects, the tooth wear was scored by Murphy's method. Bruxism level in these subjects was also recorded for 5 consecutive nights in the subject's home environment using a force-based bruxism detecting system. The relationship between the tooth wear score and bruxism data was evaluated statistically. RESULTS: Correlation analysis between the Murphy's scores of maxillary and mandibular dental arch and bruxism event duration score revealed no significant relationship between tooth wear and current bruxism. CONCLUSION: Tooth wear status is not predictive of ongoing bruxism level as measured by the force-based bruxism detection system in 30-year-old Japanese subjects.

Adult↗

PubMedDate not supplied

A short-term clinical evaluation of immediately restored maxillary TiOblast single-tooth implants.

PURPOSE: The purpose of this study was to evaluate the short-term clinical outcome of single-tooth implants placed in the maxilla and immediately restored using cementless friction-fit temporary crowns. MATERIALS AND METHODS: Twenty-five patients consecutively referred to a private specialist practice for the replacement of failing or missing maxillary teeth were treated by means of immediate temporization of their single-tooth implants. Where teeth were still present, implants were placed immediately following extraction. Provisional crowns were fabricated on a special friction-fit coping by means of autopolymerizing acrylic resin. Definitive crowns were placed a mean of 4.5 months after surgery. Implant survival was recorded along with the level of the marginal bone relative to a fixed reference point 1 year after placement. Any adverse soft tissue changes were also noted. RESULTS: A total of 28 Astra Tech ST dental implants were placed. The overall survival rate at the end of the study was 96.4% for implants which were in function for periods ranging from 15.7 to 27 months. One patient, a smoker, lost 1 implant within 1 month of surgery. Mean marginal bone loss was 0.40 mm (range 0 to 1.53 mm) 1 year after placement of the implants. Many implants (37.5%) had no observed bone loss. No implants or crowns have been lost during the functional loading period. One implant was associated with an unfavorable recession of soft tissues; however, most maintained an esthetic gingival architecture. Eleven of 28 provisional restorations needed treatment; 6 required replacement during the temporization period, and 5 required cementation because of looseness. The ease of removal of the crowns allowed regular access for irrigation with chlorhexidine and thus maintenance of soft tissue health. DISCUSSION: The need to provide provisional restorations for single-tooth gaps often presents challenges. An immediate temporary partial denture or adhesive prosthesis may be unacceptable or impractical. The current study describes a simple method for the immediate temporization of single-tooth implants. The results did not indicate any negative influence on osseointegration or short-term survival once the implants were functionally loaded. CONCLUSION: Immediate temporization of maxillary single-tooth implants can be both safe and predictable, and it appears that the procedure can yield favorable soft tissue esthetics.

Acrylic Resins↗

PubMed2004

The natural tooth pontic; simplified.

This paper's objective is to describe a simple, economical and fast method to replace a single tooth. Utilizing an indirectly fabricated composite resin framework reinforced with polyethylene fiber and the existing tooth as pontic. This tooth can be the natural tooth or the restorative crown. In addition, this particular design allows for exact repositioning of the coronal part of the extracted tooth in its original intra-oral 3-dimensional position. This chairside technique does not require laboratory involvement.

Denture Design↗

PubMed2004

Factors affecting postmortem tooth loss.

Unassociated human bones are a particular problem during the exhumation of mass graves and a factor that limits anthropological and paleopathological analyses from archaeological contexts. Extensive anthropological literature has focused on the complex taphonomic factors that influences bone assemblages, but little attention has been paid to postmortem tooth loss and factors affecting this process. The following study focuses upon the influence of different factors on postmortem tooth loss. Three samples were investigated in the study: a medieval church cemetery containing 110 individual skeletal remains, and two samples from a series of mass graves made within the same time period in 1999, containing 402 bodies. The frequency of postmortem tooth loss was analyzed relative to postmortem interval for each sample, excavation methods, age distribution, and presence of bone loss associated with periodontal disease. Our results indicate that the degree of alveolar bone loss significantly affected both antemortem and postmortem tooth loss and that the frequency of postmortem tooth loss has the strongest correlation to time since death. These findings suggest that additional care should be taken when exhuming remains from older contexts.

Adolescent↗

PubMed2004

Amorphous calcium phosphates for tooth mineralization.

The destruction of tooth structure through caries and erosive processes is due to two types of acidic challenges that affect the tooth in different ways. Acidic attack by cariogenic bacteria initially produces subsurface lesions that weaken the enamel and, if left unchecked, can progress through the enamel and dentin and eventually into the pulpal cavity. Erosive attack by acidic foods and beverages removes mineral from the surface of enamel and initially causes dulling and loss of tooth luster; if left unchecked, it can progress to a more severe loss of enamel thickness and contour. This article focuses on the potential means of improving the cosmetic appearance of teeth by depositing mineral into surface defects. Several approaches use the unique properties of amorphous calcium phosphate (ACP) compounds, which have the highest rates of formation and dissolution among all the calcium phosphates. ACP has been shown to rapidly hydrolyze to form apatite, similar to carbonated apatite, the tooth mineral. Products containing ACP or ingredients that form ACP can include toothpastes, mouth rinses, artificial saliva, chewing gums, topically applied coatings, and other vehicles for topical use. When applied, they readily precipitate ACPs on and into tooth-surface defects. These products hopefully will provide users with new tools to restore and enhance the smoothness and luster of their teeth.

Calcium Phosphates↗

PubMed2005

Tooth width and arch dimensions in normal and malocclusion samples: an odontometric study.

The purpose of this study was to establish tooth width and arch dimensions in normal and malocclusion samples and to compare tooth width and arch dimensions between males and females in normal and malocclusion samples. A total of 120 pairs of orthodontic study casts were included in the study. An electronic digital caliper was used for the measurements. Descriptive statistics and the t-test were used for the statistical analysis of the data. Tooth width and arch dimensions were established in normal and malocclusion in the present study. Significant differences were found in tooth width between normal and malocclusion samples. However, no significant difference was observed in arch dimensions. Furthermore, there was statistical significant difference in tooth width between males and females where the males showed higher mean values. The same was true when arch dimensions were compared. The results of the current investigation are of great value to the anthropologist as well as to the orthodontist in understanding dimensional arch criteria and orthodontic arch wire selection. Furthermore, it helps the prosthodontist in the selection of the correct shape and size of stock impression trays and of suitable molds of artificial teeth for fixed and removable prostheses.

Adolescent↗

PubMedDate not supplied

Oral clearance of an acidic drink in patients with erosive tooth wear compared with that in control subjects.

PURPOSE: The aim of this study was to compare the clearance of an acidic drink in patients with tooth wear caused by regurgitation erosion to that in patients without tooth wear. MATERIALS AND METHODS: Oral clearance was measured using antimony electrodes at 4 soft tissue sites around the mouth in the patients with erosion caused by regurgitation and compared to a matched control group. The data were analyzed for pH at the resting state, the time below 5.5, and the lowest recorded pH. In addition, the resting hydration levels and viscosity of fluid from the minor salivary glands, the pH of resting saliva, and the flow rate and buffering capacity of stimulated saliva were compared between the 2 groups of patients. RESULTS: The pH recorded at the tip of the tongue reached a lower level in the controls than in those in the erosive tooth wear group (P < .05) and the time that the pH remained below 5.5 was longer in the controls than those with tooth wear (P < .05). The flow rate from the minor salivary glands (P < .05) and the viscosity of resting saliva appeared to differ between the two groups (P < .001). CONCLUSION: Oral clearance at the tip of the tongue, measured as a function of the lowest pH reached and the time below 5.5, was quicker in those with erosive tooth wear than the controls. It is suggested that this may be a result of a feedback mechanism from constant exposure of the oral environment to low pH.

Acids↗

PubMed2005

[Gene expression of transcription regulator LMO 4 in tooth morphogenesis].

OBJECTIVE: To investigate the expression of transcription regulator LMO4 mRNA in the developing mouse molar and compare the expression pattern of LMO4 with that of Shh signaling molecule. METHODS: Wild-type embryos used in this study (E11.5-P1.5) were generated by mating Kun-Ming mice. The expression pattern of LMO4 during organ development was carried on by whole-mount in situ hybridization. The expression patterns of LMO4 and Shh mRNA during molar development were analysed by section in situ hybridization. Immunohistochemical staining of PCNA was carried on by SP method. RESULTS: LMO4 mRNA was widespread at early embryonic stages (E11.5) with positive hybridization signal in the mandibular reason, limb bud, brain, epidermis and somites revealed by whole-mount in situ hybridization. Section in situ hybridization showed that LMO4 was expressed in the tooth bud, the two tips of the enamel organ and the cervical loop from E13.5 to E16.5. While Shh was localized in the enamel knot on E14.5. On E18.5-P1.5, LMO4 transcripts were distributed in the ameloblast and the stratum intermedium. On E13.5-E16.5, the tooth bud cells and the cervical loop cells were PCNA positive. These were the same regions that showed LMO4 mRNA expression. CONCLUSIONS: LMO4 was confined to the dental epithelium and had spatial temporal expression patterns during tooth morphogenesis. The expression patterns of LMO4 and Shh were similar. In early tooth development, LMO4 might regulate cell proliferation. In late tooth development, it might participate in the ameloblast differentiation.

Adaptor Proteins, Signal Transducing↗

PubMedDate not supplied

Assessing the tooth-restoration interface wear resistance of two cementation techniques: effect of a surface sealant.

This study compared (1) the tooth-restoration interface width of conventional and "resin coating" cementation techniques, (2) the toothbrushing wear resistance of the two interfaces and (3) this study evaluated the influence of a restoration surface sealing on toothbrush wear resistance on both cementation technique interfaces. Mid-coronal buccal surfaces of 40 bovine teeth were ground to obtain a flat enamel surface. For each specimen, a 3 mm x 4 mm x 3 mm dimension rectangular cavity was prepared. The teeth were divided into four groups. Two groups (RC) received a "resin coating" (ED Primer + Tetric Flow) prior to cementation. The remaining two groups (NC) served as non-coated groups. All teeth were restored with composite inlays (Z250) fabricated by the indirect method and were cemented with dual cure resin cement (Panavia F). After finishing the margins, one group from each of the cementation techniques (RC+S and NC+S) had the tooth-restoration interface protected with a restoration surface sealant (Biscover). The specimens were subjected to 100,000 brushing abrasion cycles. The tooth-restoration width was obtained using a Hommel Tester T 1000-basic profilometer and Turbo Datawin NT 1.34 Software (microm). The interface wear (vertical loss/microm and area/microm2) was calculated with Image Tool 3.0 Software. Data were analyzed with Student t-test, one-way analysis of variance and Tukey test (alpha=0.05). Mean interface width for the NC group was 67 microm and 72 microm for the RC group. The student t-test showed no significant differences between groups (p=0.53). ANOVA showed significant differences (p<0.01) in vertical loss among groups (NC: 49.30 microm; NC+S: 7.90 microm; RC: 27.15 microm; RC+S: 4.74 microm). Also, ANOVA showed significant differences (p<0.01) in worn areas among groups (NC: 2,008 microm2; NC+S: 128 microm2; RC: 1,580 microm2 and RC+S: 88 microm2). No differences were found in tooth-restoration interface width and worn area between conventional and "resin coating" techniques. "Resin coating" interface presented reduced vertical loss. Restoration surface sealing provided reduced wear in tooth-restoration interface for both techniques.

Acrylates↗