A comparison of three methods to accurately measure root length

Measuring the severity of root shortening after orthodontic treatment is a common problem in the dental fields as well as in litigation, legislation, and the ethics arena. The most common method to evaluate root length shortening is by using periapical radiographs. Surprisingly, root elongation after orthodontic treatment in adult patients was reported in the past. The aims of this study were to measure the effects of angular changes between the tooth and the film on the length of the image of a tooth model, to compare three methods to accurately measure root length in different films, and to find the most accurate reference points on the tooth for calculating root lengths. Five amalgam dots were placed on an acrylic model of a maxillary central incisor: ie, most apical, most incisal, mesial CEJ, distal CEJ, and most apical CEJ on the buccal side. The tooth model was placed in a special jig and radiographed at four different film-to-tooth angulations. Root and crown lengths were measured on both the model itself and on a computer monitor displaying the image that resulted from scanning the film into the computer. The results revealed that angular changes between the tooth and the film affect the measured tooth length. The midpoint between the mesial CEJ point and the distal CEJ point (median CEJ) was the best reference point for measuring root length. This was true when the calculations were done with the rule-of-three formula.     

A comparison of four epidemiological methods of assessing periodontal disease

Periodontal disease was assessed using PI and P.D.I. and radiographic and mobility assessments. Analysis of data by worst score in the mouth and by individual teeth indicated that PI did underestimate the severity of periodontal disease. P.D.I. diagnosed destructive periodontal disease in 45.0 per cent of mouths and 38 per cent of teeth considered free of destructive periodontal disease using PI. P.D.I. detects more destructive periodontal disease than PI at the lower radiographic scores (4 and 5); at radiographic scores 6 and 7 the disparity between the P.D.I. and PI decreased. The measurements of mobility underestimated the severity of periodontal disease; ninety five per cent of all teeth examined were considered to have a mobility score of 0 whereas 20 per cent were considered free of periodontal disease using PI. Radiographic examination did not add significantly to the PI and P.D.I. examinations.     

A comparison of four epidemiological methods of assessing periodontal disease

An epidemiological study of periodontal disease, using four methods of assessment of severity of periodontal disease, was conducted on a representative sample of 1,976 New Mexicans aged 18 to 44 years. Periodontal disease was assessed using PI and PDI and radiographic and mobility assessments. One objective of the study was to assess whether radiographic scores and measurements of clinical mobility added significantly to the precision of discrimination between the severity of periodontal disease in populations when using the PI and PDI. Findings indicated that the PI discriminated between population groups as efficiently as the PDI plus radiographic and mobility scores. In this study females had less severe periodontal disease than males; Anglos had less severe disease than Spanish-Americans, Mexicans, American-Indians, and Negroes; persons with a greater number of years of schooling and persons in the higher socioeconimic groups had less severe periodontal disease than persons with fewer years of schooling and in the lower socio-economic groups respectively; urban and rural persons had a similar severity.     

A comparison of four simulation and instructional methods for endodontic review

The effects of four different endodontic self-instructional review formats (slide-tape, latent-image simulation, computer text simulation, and computer-assisted video interactive simulation) on senior clinical endodontic performance are compared. The senior class of 105 students was divided into eight groups of 13-14 academically equivalent students prior to initiating endodontic treatment in the 1985-86 academic year. With the exception of the control group, each participated in a program designed to review principles of endodontic diagnosis and treatment. All clinical endodontic cases were subsequently critiqued by a calibrated panel of two general dentist and one endodontist. Overall, students in the study group made fewer diagnostic errors compared with those in the control group, while the error reduction in clinical treatment was not significantly reduced between the two groups. No significant difference in error reduction was noted between the simulation formats. Student evaluations, as well as comparative developmental expenditures, are discussed.     

The relationship of arch length to alterations in dental arch width.

An accurate method is presented for forecasting alterations in arch length related to various width increases in each dental arch. It is based on combined beta and hyperbolic cosine functions which express the expanded dental arches with correlation coefficients of r = 0.98, between measured data and representations of the dental arch. When the midpalatal suture is expanded, canine width and molar width alterations are not equal because the line of action of the expanding force is anterior to the center of resistance of the dentomaxillary complex. Therefore, canine to molar width ratio alterations of 1:1, 1.25:1, and 1.5:1 are examined, and simple linear functions are presented for purposes of predicting changes in arch length.     

Fracture toughness comparison of three test methods with four dental porcelains.

OBJECTIVE: The aim of this study was to compare three fracture toughness test methods, using four commercial dental porcelains. MATERIALS AND METHODS: The fracture toughness test techniques involved were: the single-edge-notched beam (SENB), the indentation strength method (IS), and a rather convenient ASTM standard for advanced ceramics, which is still rarely used in dental ceramic research, the Chevron-notched beam method (CN). Duceram, Duceram LFC, Sintagon Zx and Carrara Vincent were chosen for study. Data was analyzed by two-way and paired ANOVA. RESULT: No statistical difference was found between the CN and SENB methods with four dental porcelains, but IS was not always in statistical agreement with SENB or CN. Statistical agreement among all three methods occurred only with Duceram LFC. CONCLUSION: The different test methods did not always lead to the same ranking or values of fracture toughness. Yet the toughness results of the SENB method were comparable to those of the CN method for all the four dental porcelains tested in this study.     

A clinical comparison of four denture adhesives.

The influence of four denture adhesives (Fittydent, Super Poligrip, Super Wernet's, and tragacanth) on patients' opinions of 10 aspects of denture use was studied. The adhesives were applied in turn to the existing complete dentures of 32 patients in a sequence determined by eight randomly chosen 4 x 4 Latin squares of different treatments. Subjective views of the patients indicated that one product significantly improved denture retention and had other favorable features.     

A comparison of methods for predicting the size of unerupted permanent canines and premolars

The aim of this study was to examine the reliability of eight methods for determining the mesio-distal crown diameters (MDD) of the permanent canines and premolars (C, P(1), and P(2)). The study models of 120 children (60 boys and 60 girls) aged from 14 to 18 years treated in orthodontic clinics were measured using Seipel's method, with callipers accurate to 0.01 mm. The correlation coefficients were determined between the MDD of C, P(1), and P(2) measured on the study models and the sums calculated using various other methods. The correlation coefficients derived by comparison with the methods of Moyers, Tanka and Johnston, Droschl et al., Legovi? and Hauz, and Berendonk-Nawrath showed a tendency to over-estimate the MDD of C, P(1), and P(2), while the regression methods of Gross and Hasund, Bachmann, and Tr?nkmann et al. under-estimated the values. Bachmann's method appeared to give the most reliable results.     

A comparison of four commonly used local analgesics.

In a double-blind, cross-over, clinical study with nine probands, the efficiency parameters of four commonly used local analgesics were evaluated: 2% Carbocain with adrenaline 1:200,000, 3% Citanest with Octapressin 0.03 iu/mul, 3% Carbocain Dental, and 2% Xylocain with adrenaline 1:80,000. It was found that 3% Carbocain Dental (no vasoconstrictor content) demonstrated significantly shorter duration of analgesia than the other solutions in the soft tissues as well as in the dental pulp. 3% Citanest with Octapressin exhibited the longest soft tissue duration, but as far as duration of tooth analgesia was concerned there was no significant difference between 3% Carbocain Dental and 2% Carbocain with adrenaline. The longest duration of tooth analgesia was shown with 2% Xylocain with adrenaline; this solution also possessed the highest frequency of analgesia and extent of analgesia. All probands personally preferred injections with 3% Carbocain Dental as injection with this solution resulted in the least discomfort.     

A comparison of four root canal obturation methods employing gutta-percha: a computerized analysis of the internal structure.

The purpose of the present investigation was to compare the internal structure of gutta-percha for presence/absence of empty spaces when used in four different obturation methods: thermoplastic, chloroform-softened, thermomechanical, and warm lateral condensations. Each obturation was performed five times in a metal mold representing a root canal system. Following obturation the mold was disassembled and the gutta-percha was freeze-fractured at the 1.0, 3.5, and 6.5 mm levels as measured from the tip of the obturations. The fractured gutta-percha was placed in a scanning electron microscope, the image transferred to a computer, and converted to digital data. The results were subjected to statistical evaluation. The results demonstrated no difference between the obturation methods at the 1 mm level, however at the 3.5 mm level, thermomechanical condensation produced an internal structure characterized by a greater number of empty spaces (p < 0.0007). At the 6.5 mm level, thermomechanical condensation differed only from the chloroform-softened gutta-percha (p < 0.01).     

Temporomandibular joint mobility assessment: a comparison between four methods

SUMMARY Temporomandibular joint (TMJ) mobility is assessed in different ways. Measurement of the interincisal distance in maximal mouth opening added to the vertical overlap of the dentition, i.e. linear mouth opening (LMO); measurement of angular displacement of the mandible relative to the cranium at maximal mouth opening, i.e. angle of mouth opening (AMO); assessment of the condylar position relative to the articular eminence performed on transpharyngeal radiographs in maximal mouth opening, i.e. condylar mobility (CM); measurement of angular displacement of the mandible at maximal mouth opening relative to the closed mouth position of the mandible, assessed on transpharyngeal radiographs in maximally opened and in closed mouth position, i.e. radiographic angle of mouth opening (RAMO). To compare these TMJ mobility assessment methods and to analyse the relationship between LMO, AMO and mandibular length (ML), 28 healthy volunteers (13 females, 15 males), mean age 29.6 years (range 21–41) with a symmetrical mouth opening pattern were assessed. LMO, AMO, ML, and RAMO were measured and CM was assessed on transpharyngcal radiographs. LMO and AMO were strongly and significantly related (r=0.71). LMO was significantly influenced by AMO and ML. No significant differences between AMO and RAMO were found. CM was strongly and significantly related to AMO (r=0.72) and weakly but significantly related to LMO (r=0.42). Based on the results of this study recommendations are made regarding the appropriate application of TMJ mobility assessment methods.     

Effect of molar rotation on arch length

The aim of this study was to evaluate the effect of maxillary first molar rotation on arch length in patients whose Class II, division 1 malocclusion was treated with a straight-pull headgear. The sample included 19 children who represent a subset of a population enrolled for 2 years in a prospective clinical trial of Class II treatment. The inner bow was adjusted at monthly visits and the average distalizing force was 14-16 oz per side. Measurements were made with digital calipers on casts obtained at baseline and at a time point averaging 16 months (SD 3 months) into treatment. Molar movement was related to a coordinate system referenced to the midpalatal raphae and the occlusal plane through a palatal plug that could be transferred to successive casts of the same patient. Distances from the cusp tips were measured to the reference system. The distal and lateral displacement, and the rotation of the molars over time were then computed. High correlations were observed between molar rotation and tooth displacement (that is the net differential movement between the mesiobuccal - MB - and mesiopalatal - MP - cusps): r=0.9, p=0.0001 (left side); r=0.8, p=0.0001 (right side). The average rotation of the molar was 15.4 degrees (SE+/-3.80) on the left side and 10.8 degrees (SE+/-2.20) on the right side. The average differential displacements between the MB and MP cusps were 1.04 mm (SE+/-0.29) (left) and 0.73 mm (SE+/-0.23) (right). The differences between the two sides were not statistically significant. The molar rotation did not correlate with any of the following parameters: initial tooth position; initial distance between the MB and MP cusps as a correlate of molar anatomy; transverse (mostly buccal) movement of the MB and MP cusps; distal movement of the tooth, as measured by the total displacement of the MB and MP cusps. This study qualifies the relationship between molar rotation and increase in arch length. The mean total distal movement of the molar was larger (nearly 3 mm) than the average contribution of molar rotation to space gain (about 1 mm), suggesting that the distal movement of the tooth was a combination of rotation and translation (or tipping). The contribution of the molar rotation is more significant with a smaller total displacement of the tooth.     

An in vitro comparison of 10 radiographic methods for working length estimation

The aim of this in vitro study was to assess the efficacy of 10 currently available methods of producing radiographic images, two conventional and eight rapid, in working length estimation. Thirty extracted teeth comprising 42 root canals were mounted in blocks of poly(methylmethacrylate) and access cavities prepared. A size 15 Hedstrom file was inserted into each root canal and sealed into position. Each tooth was imaged by 10 methods: combinations of conventional (D^? and E^? speed) film processed with conventional manual chemistry or two proprietary brands of rapid processing chemistry (Westone Rapid Dental and Kodak ‘Rapid Access’), Super X30 packet processed film, Hanshin Hi-Fi and Nix NF45-100 films processed using their respective manufacturers' monobath solutions, and the Sens-A-Ray digital X-ray system. Comparisons of length of file visible were made between the D-speed films (conventionally processed using Kodak chemistry) and the nine other radiographic methods. No significant differences in percentage length of file seen were found between D-speed film processed with conventional chemistry and E-speed film processed with the same chemistry or between D-speed film processed with conventional chemistry and six of the rapid imaging systems studied. The percentage length of the file visible was significantly less for Sens-A-Ray (P=0.02) and for Nix NF45-100 film (P<0.005)when compared with D-speed film processed with conventional chemistry. This difference in file length is probably not of clinical importance for the Sens-A-Ray images but may be so for the Nix images.