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PubMed2003

Incisor trauma and early treatment for Class II Division 1 malocclusion.

This study investigated incisor trauma in children with overjets greater than or equal to 7 mm who were enrolled in a clinical trial of 2-phase early orthodontic treatment for Class II malocclusion. In phase 1, children were randomly assigned to treatment in the mixed dentition with either modified bionator or combination headgear or to a group in which treatment was delayed until the permanent dentition. All children received comprehensive treatment during phase 2 if necessary. At the start of the trial, 29.1% of the patients had already had some incisor trauma. This was not significantly related to dental developmental age. During the trial, there was an increase in trauma in all 3 groups, but the magnitude of this increase was not significantly greater in the group for which treatment was delayed until the permanent dentition. This might suggest that orthodontic intervention aimed at reducing trauma should begin very soon after the eruption of the maxillary incisors. However, the injuries tended to be minor, and the expected cost of treatment related to incisor trauma was small compared with the expected additional cost of a 2-phase orthodontic intervention.

Activator Appliances↗
PubMed2001

The influence of maxillary central incisor position in complete dentures on /s/ sound production.

STATEMENT OF PROBLEM: The insertion of prosthodontic restorations often leads to speech defects, most of which are transient but nevertheless a source of concern to the patient. For the dental practitioner, there are few guidelines on designing a prosthetic restoration with maximum phonetic success. PURPOSE: This study investigated the effect of different maxillary central incisor positions on phonetic patterns. MATERIAL AND METHODS: The inclination angle of central incisor blocks in duplicate complete maxillary dentures was changed in a range of -30 degrees to +30 degrees from the original position (0 degrees). Test words and sentences were acoustically analyzed. Spectral parameters such as first peak, noise band (defined by upper and lower limits of the most intensively blackened frequency area), Fast Fourier Transformation power spectrum, energy spectrum, and time were investigated. Influences of oral stereognosis, hearing, and age as cofactors on /s/ articulation were also taken into account. RESULTS: The change of incisor block angle in both directions usually caused a poorer execution of the /s/ sound. The labial angulation seemed to have a greater effect than the palatal angulation. The most significant changes were those in the noise band and energy spectrum. CONCLUSION: Immediate phonetic adaptation of prosthetic restorations in the maxillary incisor region can be achieved only if the original position of the natural teeth is transferred to the denture. Although these misarticulations are, in most cases, likely to disappear within a few weeks, they may persist and even lead to psychosocial problems. A better understanding of the causes of misarticulation and the limits of adaptation according to certain morphologic parameters of dentures is important.

Adaptation, Physiological↗
PubMed2003

Does labial movement of lower incisors influence the level of the gingival margin? A case-control study of adult orthodontic patients.

It has been suggested that proclination of the lower incisors results in gingival recession. Proclination is, however, a valuable alternative to extraction especially when considering facial aesthetics in adult patients. The aim of this study was to evaluate the association between the extent of labial movement of the lower incisors and the prevalence and severity of gingival recession in orthodontically treated adult patients. A retrospective case-control study based on the analysis of study-casts and intra-oral slides of 300 adult patients was carried out. One hundred and fifty pairs matched by age and sex were selected using simple random sampling. Recordings of gingival recession were made using casts as well as intra-oral slides. Dental displacement was measured on casts comparing the measurements before and after treatment. The intra-oral slide recordings of gingival recession were more reliable than the cast recordings. Although the difference in prevalence of individuals with gingival recession among cases and controls was statistically significant (P < 0.001), no significant difference in the mean recession value could be found between cases and controls (P > 0.10). The mean value of the extent of recession of the four lower incisors amounted to 0.36 mm for treated subjects and 0.22 mm for the controls. This mean difference of 0.14 mm between members of a pair was not clinically relevant. Faced with the alternative between extraction and labial movement of lower incisors the present study indicates that the latter is a valuable alternative leading to no clinically relevant deterioration of the periodontium.

Adult↗
PubMed2005

Developmental absence of maxillary lateral incisors in the Portuguese population.

The aim of this study was to evaluate the prevalence and clinical manifestation of developmental absence of maxillary permanent lateral incisors in the Portuguese population. The study group comprised 16 771 patients observed between 1993 and 2000 at the Faculty clinic. Two hundred and nineteen patients were found to have missing upper lateral incisors (131 females and 88 males, with ages ranging between 3 and 71 years), a prevalence of 1.3 per cent in this population. Absence of these teeth was bilateral in 44.7 per cent of the patients; of the unilateral cases, 33 per cent occurred on the right side and 21.9 per cent on the left side. In children under 8 years of age (n = 12), two (0.26 per cent) also had developmental absence of the primary lateral incisors, one unilateral and the other bilateral. Among the 121 subjects with unilateral developmental absence, the contralateral maxillary lateral incisor was found to be microdont in 57.1 per cent (right lateral 23 per cent, left lateral 34.1 per cent), suggesting the possibility that microdontia represents a variable expression of the same developmental defect that results in absence.

Adolescent↗
PubMed2002

Radiologic localization of esophageal level: comparison with distance from incisor at endoscopy.

RATIONALE AND OBJECTIVES: The esophageal level on radiography was compared with that at endoscopy by establishing a relationship between the radiologic landmarks, i.e., the vertebral level and the distance from the carina, and the distance from the incisor at endoscopy. METHODS: Three hundred ninety spot films in 65 patients who underwent endoscopic retrograde cholangiopancreatography were analyzed. Six spot films were obtained for each patient, wherein the distances of the endoscopic tip were located at 20, 25, 30, 35, 40, and 45 cm from the incisors. On each radiogram, the vertebral level scores were measured as 1 to 12, for the location of the endoscopic tip at the levels of T1 through T12, respectively. When the endoscopic tip was located at the lower half of the vertebral body, 0.5 point was added to the vertebral level score and when the tip was noted at the upper half of it, no additional score was given. The distance between the endoscopic tip and the carina was also measured. Correlations of the distance of the endoscopic tip from the incisors on endoscopy with the vertebral body levels and the distance from the carina on radiography, accounting for patient height, were analyzed by multiple linear regression and equations were extracted. RESULTS: Equation 1 for the vertebral level score (VL) for a given distance of endoscopic tip from incisor (DI) at a given patient height (H) was VL = 0.432DI - 0.048H + 0.099 (r2 = 0.968). Equation 2 for the distance from the carina (DC) for a given DI at a given H was DC = 0.957DI - 0.137H - 5.841 (r2 = 0.983). Two tables denoting radiologic VLs and DCs for given endoscopic DIs and patients' heights were generated using these equations. CONCLUSIONS: Regressed equations and tables will enable radiologists to better localize the esophageal lesions that are seen at endoscopy, and vice versa.

Body Height↗
PubMed2005

Dynamic finite element analysis of the human maxillary incisor under impact loading in various directions.

The aim of this study was to investigate fracture patterns occurring when a human upper central incisor is subjected to impact loadings at various angles. A two-dimensional finite element (FE) model of the maxillary incisor and surrounding tissues was established. The structural damping factor for the tooth was then calculated and assigned to the model. Dynamic FE analysis was performed to stimulate the associated impacts. Time-dependent traumatic forces at 0 degrees, 45 degrees, and 90 degrees labially to the long axis of the tooth were applied to the model. Von Mises's equivalent stress contours within the FE models were calculated. Our results indicated that tooth damping lagged behind peak stress by 0.05 ms. In addition, we found that impact direction played an important role in terms of outcome for the fractured incisor. These results can, in part, explain the mechanisms underlying the alternative outcomes when upper incisors are subjected to impact.

Bite Force↗
PubMed1994

Forces acting on the maxillary incisor teeth during laryngoscopy using the Macintosh laryngoscope.

We determined the forces on the maxillary incisors during routine laryngoscopy in 65 adult patients. The forces were measured by a strain gauge based sensor positioned between the handle and the blade of the laryngoscope. The mean maximal force acting on the maxillary incisors was 49 N. In patients without maxillary incisors, the force acting on the gums was significantly lower at 21 N (p < 0.001). These results suggest that, despite traditional advice to the contrary, a levering movement of the laryngoscope, using the maxillary incisors (or gums) as a fulcrum, is common practice. Biomechanical analysis revealed that, although levering is not the preferred movement, it is an efficient way of bringing the glottis into view. These results may have implications for future laryngoscope design.

Adult↗
PubMed2006

Root canal morphology of mandibular incisors in a Jordanian population.

AIM: To investigate the root canal morphology of mandibular incisors in a Jordanian population using a canal staining and tooth-clearing technique. METHODOLOGY: Four hundred and fifty extracted mandibular incisors were collected from dental clinics within north Jordan. Following pulp tissue removal and staining of the canal systems, the teeth were decalcified with 5% nitric acid, dehydrated with ascending concentrations of alcohol and rendered clear by immersion in methyl salicylate. Cleared teeth were examined by eye and the following features were evaluated: (i) number and type of root canals; (ii) presence and location of lateral canals and intercanal communications; (iii) location of apical foramina; and (iv) frequency of apical deltas. RESULTS: The majority of mandibular incisors had a single canal (73.8% of teeth possessed a Type I canal system). Although 26.2% of the roots possessed two canals, only 8.7% had two separate apical foramina. CONCLUSIONS: The prevalence of two canals in this group of mandibular incisors was 26.2% and is within the range of previous studies performed on populations of different racial origin.

Coloring Agents↗
PubMed1996

Bilateral talon cusps on primary central incisors: a case report.

Talon cusp is an uncommon anomaly in the primary dentition. The present report describes a case of bilateral talon cusps on the maxillary primary central incisors of a 17-month-old Jordanian-Arab boy, bringing to seven the total cases reported in the literature. Both central incisors exhibited a sharp prominent accessory cusp on the palatal surface which extended from the cemento-enamel to the incisal edge. The cusp on the right incisor was attached to tooth surface, forming a T-shape crown outline. whereas the cusp on the left incisor projected away from the rest of the crown. The anomalous cusps were a source of tongue irritation and occlusal interference.

Child, Preschool↗
PubMed2006

Behaviour of primary incisor caries: a micromechanical study.

OBJECTIVES: To date, there has been no attempt to assess the mechanical properties of the entirety of a smooth-surface carious lesion in primary teeth, despite the fact that these lesions are not only common, but clinically challenging. Therefore, the aim of this study was to describe the hardness and modulus of elasticity across smooth surface lesions of primary incisors. STUDY DESIGN: An in vitro study of the micromechanical properties of primary incisors. MATERIALS AND METHODS: Carious primary incisor teeth were set in resin, sectioned and polished. A series of indentations using the ultra-micro-indentation system were conducted in fully hydrated carious and sound dentine from the minimally affected pulpal region towards the tooth surface. A single set of indentations were duplicated for sound dentine. RESULTS: Although the mechanical properties of the carious dentine varied between the test teeth, the median hardness of the surface, middle and inner (pulpal) region of the carious dentine was 0.01, 0.10 and 0.28 GPa, respectively. The modulus of elasticity of the surface, middle and inner (pulpal) carious dentine was 0.12, 2.16 and 5.98 GPa, respectively. The mechanical properties of the sound dentine varied less, and were consistent between the pulpal and surface regions. Examination of the individual series of indentations indicated that, although the majority of the test teeth showed a decrease in the mechanical properties from the 'unaffected dentine' to the surface of the lesion, in the last 300-500 microm, both the hardness and modulus of elasticity showed a dramatic increase. CONCLUSIONS: This study has confirmed that the carious process has a deleterious effect on the mechanical properties of dentine in primary incisors. This, in turn, increases the likelihood of restorative failure. However, the slight increase in mechanical properties seen at the surface of the carious lesion suggests an increase in mineral content.

Biomechanical Phenomena↗
PubMed2004

Laser Doppler flowmetry of luxated permanent incisors: a receiver operator characteristic analysis.

Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood-flow (PBF). Dental luxation injuries have been associated with significant PBF reduction. The purpose of this study was to describe diagnostic characteristics for different session-related threshold PBF values for detection of specific adverse outcomes. In 61 trauma patients, a single maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous control tooth were investigated by LDF to assess local PBF values. Perfusion units (PU) were taken 12 weeks (session I) and 24 weeks (session II) after splint removal. The ability of session I-related PBF measurements at 2.8, 6.4 and 10.1 PU levels, and of session II-related ameasurements at 2.4, 6.3 and 10.2 PU levels to identify adverse outcomes occurring 36 weeks after splint removal was investigated. Adverse outcomes were classified as type I (periapical radiolucency), type II (grey discoloration), and type III (periapical radiolucency and grey discoloration of crown). Receiver operator characteristic curves were used to evaluate the sensitivity and specificity of PBF assessments. There was no significant difference in PBF values between session I and session II (P > 0.05) for teeth without an adverse outcome, and those with a type I, II or III outcome (P > 0.05). The PBF measurements did not change over time for the contralateral incisors (P > 0.05). A type I, II and III outcome occurred in 36, 21 and 12% of the incisors, respectively. The best likelihood ratio was found for the PBF 6.4 PU level at session I and incisors associated with a type I (20.8) and type II outcome (15.2). The PBV of 6.4 PU demonstrated a sensitivity of 96% and a specificity of 59% for type I outcomes, and a sensitivity of 100% and a specificity of 50% for type II outcomes. The data suggest the LDF test to be a valuable diagnostic adjunct for luxated teeth showing signs of adverse outcomes.

Adolescent↗
PubMed2006

Retrospective evaluation of mandibular incisor replacement with narrow neck implants.

The authors have retrospectively evaluated the clinical results of mandibular incisors replacement with narrow neck implants (NNI). Thirty-one patients treated consecutively for single or multiple lower incisor replacement with NNI with a mean follow-up of 23 months (range 18-42 months) were included in the study and were divided into three groups: single tooth, multiple unit restoration and restorations on adjacent implants. Survival and success rates and soft tissue parameters such as modified plaque index (mPI), peri-implant probing depth (PPD), bleeding on probing (BOP) and the papilla index were analyzed. Subjective evaluation was performed by patients and clinicians on visual analogue scales. The implants and prostheses showed a survival rate of 100% and an overall success rate of 94%. The distribution of mPI outcomes showed better results for the single tooth group. BOP was present in four of eight implants (50%) in the adjacent implant group, in one out of 20 implants in the single tooth group (5%) and in one out of 16 implants in the multi unit group (6%). The adjacent implant group showed a statistically significant increase in PPD. The Papilla Index showed a better outcome distribution in single tooth and multi unit groups. Patients' evaluation of treatment outcome was satisfactory in all groups, even though the best esthetic and functional results were found in single tooth and multi unit groups. The professional evaluation showed good outcomes for the single tooth and multi unit groups and statistically significant poorer results in the adjacent implants group. With the limitations of this study, it may be concluded that the replacement of lower incisors with NNI leads to favorable functional and esthetic results in cases of single-tooth or multiple-unit replacement. Worse results are achieved if two adjacent mandibular incisors are replaced with adjacent implants.

Dental Implantation, Endosseous↗
PubMed2006

Timing of fluoride intake in relation to development of fluorosis on maxillary central incisors.

OBJECTIVES: Several studies have focused on the timing of fluoride intake relative to the development of dental fluorosis. This study reports the relationships of fluoride intake during the first 48 months of life with fluorosis on early-erupting permanent teeth. METHODS: Subjects were followed from birth to 48 months with questionnaires every 3-4 months. Questionnaires gathered data on intakes from water, diet, supplements, and dentifrice to estimate total fluoride intake. Early-erupting permanent teeth of 579 subjects were assessed for fluorosis using the Fluorosis Risk Index (FRI) at approximately age 9. Fluorosis cases were defined as having FRI definitive or severe fluorosis on both maxillary central incisors. Individuals with FRI questionable fluorosis were excluded. The importance of fluoride intake during different time periods was assessed using t-tests and logistic regression. RESULTS: One hundred and thirty-nine (24%) subjects had fluorosis on both maxillary central incisors. Mean fluoride intake per unit body weight (bw) ranged from 0.040 to 0.057 mg/kg bw, with higher intake during earlier time periods and relative stability after 16 months. In bivariate analyses, fluoride intakes during each of the first 4 years were individually significantly related to fluorosis on maxillary central incisors, with the first year most important (P < 0.01), followed by the second (P < 0.01), third (P < 0.01), and fourth year (P = 0.03). Multivariable logistic regression analyses showed that, after controlling only for the first year, the later years individually were still statistically significant. When all four time periods were in the model, the first (P < 0.01) and second years (P = 0.04) were still significant, but the third (P = 0.32) and fourth (P = 0.82) were not. CONCLUSIONS: The first two years of life were most important to fluorosis development in permanent maxillary central incisors; however, this study also suggests the importance of other individual years.

Age Factors↗
PubMed1983

Formation of the periodontal attachment in developing rabbit permanent incisors.

Permanent incisors from fetal New Zealand white rabbits aged 25-30 days in utero and from 1-20 days postnatally were processed for light microscopy. Examination of longitudinal and cross-sections revealed that cementum deposition and fiber attachment first occurred at 27 days in utero. A tooth-to-bone course of principal fibers confined to lateral aspects of the teeth was observed in 29-day fetal incisors, whereas lingually the periodontal ligament remained undeveloped as late as 5 days postnatally. In 20-day postnatal incisors, the development of the functional periodontal ligament was complete as evidenced by the fiber arrangement on all aspects of the root-analogue tooth surface. This study shows that 25-26-day fetal rabbit permanent incisors represent the end of the follicular phase, whereas 27-day fetal to 20-day postnatal teeth demonstrate distinct histologic characteristics of initial, incomplete and complete periodontal fiber attachment.

Animals↗
PubMed1983

Preparation of midsagittal semithin Epon sections of the entire secretory ameloblast population in the maxillary rat incisor.

To study cytological changes in the migrating cell layer of the ameloblasts in the rat incisor with semithin Epon sections the ideal section plane would consequently be along the midsagittal plane of the incisor. However, the small dimensions and the complex three-dimensional structure of the apical part of the odontogenic organ covered by alveolar bone make it difficult to orientate and position sections in the midsagittal plane. Serial sectioning of the apical half of the maxillary incisor in the horizontal and sagittal planes clarified the relation of the midsagittal plane of the odontogenic organ to the alveolar bone, and the changes of the sectional profile of the odontogenic organ as a function of its position on the transverse axis of the incisor. From this information a method was designed whereby the two axes of the midsagittal plane were marked directly on the block surface before sectioning, and the position of sections in the midsagittal zone of the ameloblasts standardized.

Ameloblasts↗
PubMed2005

Assessment of dental appearance following changes in incisor proportions.

This study aimed to evaluate the assessment of attractiveness of standardized changes in incisor proportions. Two original photographs, showing the maxillary anterior teeth in the frame of a smile, were computer-manipulated. From the so-produced symmetrical 'golden standard' images, two sets were constructed. Each set contained one golden standard image and seven images with different standardized changes concerning (i) width-to-length ratios of the central incisors (60-96%) and (ii) tooth-to-tooth proportions between the widths of lateral and central incisors (43-87%). The judges, consisting of three groups of individuals (24 dentists, 24 medical students, and 179 patients), ranked each photo set for attractiveness on a visual analogue scale. The width-to-length ratios were assessed as most attractive within a range of 75-85% (medical students, patients) or 75-80% (dentists), respectively. The tooth-to-tooth proportions showed the best results concerning attractive appearance within a range of 50-74% (medical students, patients) or 56-68% (dentists), respectively. No significant differences between the participant groups were found except for some extreme variations. It was concluded that a most attractive 'golden range' could be identified for both the width-to-length ratios and the tooth-to-tooth proportions of the maxillary incisors.

Adolescent↗
PubMed1997

Long-term follow-up of conservative treatment of severely traumatized maxillary incisors.

We present the case of a 26-year-old man who at the age of 9 suffered severe trauma to both maxillary central incisors. The underlying malocclusion was skeletal and classified as dental Class II/1 with severe crowding. Both the maxillary central incisors and the two lower first premolars were extracted and the patient was treated with an edgewise appliance for 2 years. Acceptable occlusal relationships were achieved following orthodontic and adjunctive treatment which consisted of reshaping the maxillary lateral incisors with composite materials and grinding the canines to resemble lateral incisors. A critical evaluation of the esthetic and functional results at the age of 26 years is presented.

Child↗
PubMed1999

Epidemiology of traumatic injuries to the permanent incisors of 9-12-year-old schoolchildren in Damascus, Syria.

This cross-sectional survey was carried out to assess epidemiological data concerning dental injuries to the permanent incisors of Syrian children. It included 1087 children aged 9 to 12 years, of both sexes, randomly selected from public and private primary schools in Damascus. The response rate was 100%. The prevalence of traumatic injuries to the permanent incisors rose from 5.2% at the age of 9 years to 11.7% at the age of 12 years (P = 0.007). The difference in prevalence between boys and girls was not statistically significant (P > 0.05). The majority (59.8%) of children who had experienced injuries to the permanent incisors reported that they were not taken to the dentist for evaluation or treatment of the damage. Among those children who had experienced traumatic injuries to the teeth 93.1% presented with untreated damage. Because some injuries were minor, such as small enamel fractures, the proportion of children who needed treatment was 63.2%. There was a tendency for children with an incisal overjet greater than 5 mm to have experienced dental injuries (P = 0.06). Children with inadequate lip coverage were more likely to have experienced dental injuries than those with adequate lip coverage (P = 0.000). The most common reported cause of injuries to the permanent incisors was violence (42.5%), followed by traffic accidents (24.1%), collisions with people or inanimate objects (16.0%) and falls (9.1%). In conclusion, traumatic dental injury may pose a serious dental public health problem.

Accidental Falls↗