Buccolingual Dimensions Research Articles

A clinical study comparing the three-dimensional accuracy of a working die generated from two dual-arch trays and a complete-arch custom tray

Statement of problem Dual-arch trays are often used by the dentists to make crown impressions of opposing quadrants simultaneously. Metal and plastic trays are available, but little is known about the accuracy of the impressions and resultant working dies. Purpose The purpose of this study was to conduct a clinical trial to compare the accuracy of gypsum working dies made from impressions with metal dual-arch, plastic dual-arch, and complete-arch custom trays. Material and methods Eight patients requiring a posterior single tooth implant restoration were selected on the basis of inclusion and exclusion criteria. A customized abutment was measured in 3 dimensions (buccolingual, mesiodistal, and occlusogingival) by use of a measuring microscope. Three polyvinyl siloxane impressions were made of the abutment with a complete-arch custom tray, a plastic, and a metal dual-arch tray. Each impression was poured with type IV improved dental die stone. The diameter (buccolingual and mesiodistal), from gingivoaxial to gingivoaxial point angle, and height (occlusogingival), gingivoaxial to occlusoaxial point angle of the abutment standard was determined by measuring each dimension several times to obtain a mean. These 3 mean values served as the controls and were compared with the same measurements of the gypsum dies generated by the 3 different impression techniques. The patient was asked to rank the 3 impressions in order of overall comfort. A multivariate repeated measures single factor ANOVA was used in the statistical analysis (α=.05). When main effects were significant, a pairwise comparison of mean values was conducted with Bonferonni adjustment for multiple comparisons. Results There were no significant differences in die accuracy among the 3 trays for the mesiodistal (3.507 mm) and occlusogingival (3.584 mm) dimensions of the implant abutment. Dies were smaller than the standard for these 2 dimensions and larger in the buccolingual dimension. There was a significant difference in accuracy between the metal and plastic dual-arch trays. The dies produced from the metal dual-arch tray were 20 μm larger than the abutment standard compared with 3 μm larger for the plastic tray. The occlusogingival dimension of the working dies was 30 to 40 μm shorter than the implant abutment. Seven of the 8 patients ranked the plastic dual-arch impression as the most comfortable and the complete-arch custom tray as the least comfortable. Conclusions Within the limitations of this study, the dimensions of working dies from a custom tray impression did not differ significantly from those created with dual arch trays. However, working dies from a plastic dual-arch tray were more accurate buccolingually than those from metal dual-arch trays.

A system for the diagnosis, placement, and prosthetic restoration of root form implants (U.S. Patent #5,769,636)

It is difficult to achieve a high degree of reproducibility when using a diagnostic wax‐up as the template for fabrication of a definitive implant restoration. Here a method for implant prosthesis treatment planning is described that allows fabrication of the provisional restoration before surgical placement of the implant. The method involves 6 steps: (1) determining the mesiodistal inclination of the implant, (2) determining the buccolingual dimension of the alveolar ridge, (3) determining the proper position of the implant, (4) fabricating the surgical guide, (5) fabricating the provisional restoration, and (6) performing surgical placement of the implant followed by immediate placement of the provisional restoration.

A system for the diagnosis, placement, and prosthetic restoration of root form implants (U.S. Patent #5,769,636).

It is difficult to achieve a high degree of reproducibility when using a diagnostic wax-up as the template for fabrication of a definitive implant restoration. Here a method for implant prosthesis treatment planning is described that allows fabrication of the provisional restoration before surgical placement of the implant. The method involves 6 steps: (1) determining the mesiodistal inclination of the implant, (2) determining the buccolingual dimension of the alveolar ridge, (3) determining the proper position of the implant, (4) fabricating the surgical guide, (5) fabricating the provisional restoration, and (6) performing surgical placement of the implant followed by immediate placement of the provisional restoration.

Implants and Restorative Dentistry

Implants and Restorative Dentistry

A clinical pilot study of the dimensional accuracy of double-arch and complete-arch impressions

Statement of Problem. It has been suggested that articulated casts fabricated with the double-arch impression technique may have superior occlusal accuracy than those fabricated with a single complete-arch impression. However, lack of tray rigidity may lead to flexure of the impression/tray complex, resulting in inaccurate dies in the bucco-lingual dimension. Purpose. This clinical pilot study compared the dimensions of dies fabricated with 3 types of double-arch impressions to dies fabricated with the conventional complete-arch, custom tray method. Material and Methods. Thirty-five addition silicone impressions were made of cast metal copings cemented onto natural teeth prepared as complete-crown abutments. Four combinations of tray types and impression material viscosity were used: (1) complete-arch, custom acrylic trays loaded with heavy-bodied material; (2) double-arch, disposable plastic trays loaded with heavy-bodied material; (3) double-arch, disposable plastic trays loaded with putty material; and (4) double-arch, reusable brass metal trays loaded with heavy-bodied material. Immediately prior to tray insertion, light-bodied impression material was syringed over all copings as a wash. The 4 copings were fabricated from cast gold and simulated metal-ceramic complete-crown thimbles with polished collars and had “projections” on the occlusal surfaces. The impressions were poured in type IV die-stone. Bucco-lingual and inter-abutment dimensions were measured. The differences between the stone dimensions and cast metal control dimensions were calculated and converted to percent dimensional change. The data were analyzed with 1-way analysis of variance, Student t tests, and Mann-Whitney tests (P<.05). Results. The plastic double-arch tray loaded with heavy-viscosity addition silicone and a low-viscosity wash produced the least accurate combination inter- and intra-abutment dimensions. For this protocol, 1.17% mean dimensional change was recorded. This result was significantly different than that obtained for the other 3 impression methods tested. No significant differences were found between the complete-arch method and protocols in which putty was loaded in a plastic or metal tray. Conclusion. Within the limitations of this pilot study, the more rigid tray/impression material combinations more accurately replicated stone dies. (J Prosthet Dent 2002;87:510-5.)

Ridge Augmentation with a Folded Acellular Dermal Matrix Allograft: A Case Report

Deformities of the dentoalveolar ridge are usually the result of developmental defects, periodontal disease, trauma, or surgical insult. Various techniques are available to correct ridge defects. In this case presentation, ridge augmentation was achieved utilizing an acellular dermal matrix allograft in lieu of an autograft. This report demonstrated an acceptable esthetic result with a significant improvement in the bucco-lingual dimension of the dental ridge. Color match was judged to be excellent. Furthermore, there was no post-surgical loss in papillae height. This case report illustrates an innovative soft tissue surgical technique for clinicians attempting to correct dentoalveolar ridge defects.

Metrical dental analysis on golden monkey (Rhinopithecus roxellana)

Dental variation in the Chinese golden monkey (Rhinopithecus roxellana) is here evaluated by univariate, bivariate, and multivariate analyses. Allometric analyses indicate that canines and P3s are positively, but other dimensions negatively scaled to mandible and maxilla, and to body size. With the exception of the mesiodistal dimensions of I1 and M3, and the buccolingual dimension of P4, mandibular dental variables show similar scaling relative to body size. Analysis of residuals shows that males have significantly larger canine, P3 and buccolingual dimensions of the postcanine teeth (M2 and M3) than females. A significant difference in shape between the sexes is found in the buccolingual dimension of the upper teeth, but not in the mandible. Unlike the situation in some other species, female golden monkeys do not exhibit relatively larger postcanine teeth than males. In fact, the reverse is true, expecially for M2s and M3s. The fact that most of the dental variables show low negative allometry to body size might be related a cold environment that has led to the development of larger body size with reduced energy loss. When the raw data are examined by Discriminant Function Analysis the sexes are clearly distinguishable.

Accuracy of casts generated from dual-arch impressions

Statement of problem. Dual-arch trays are often used to make simultaneous impressions of a prepared tooth and the opposing teeth. Many dentists are concerned with the accuracy of the casts generated from this type of impression. Purpose. The purpose of this investigation was to compare the accuracy of stone casts of a prepared tooth generated using 2 types of dual-arch impression tray/impression material combinations. Material and methods. The maxillary left first molar on a dentoform mounted on an articulator was prepared for a full-coverage gold crown. Ten impressions were made with either a plastic (P) or metal (M) tray and a polyether (PE) or vinyl polysiloxane (VPS) impression material. Each impression was cast in improved dental stone, and the buccolingual dimension of the die was measured at the midpoint of the buccal and lingual gingival margins. The prepared tooth (T) served as the control. The data were analyzed using a 2-factor analysis of variance (ANOVA) α=.05. Results. The P/VPS combination (10.673 mm) produced the largest die, followed by P/PE (10.602), T (10.508), M/PE (10.484), and M/VPS (10.472). The 2-factor ANOVA showed a significant difference between the tray types but not between the impression materials. Conclusion. The metal trays produced dies smaller than the tooth, and the plastic trays produced dies that were larger. (J Prosthet Dent 2000;84:403-7.)

Deciduous tooth size and morphogenetic fields in children from Christ Church, Spitalfields

Deciduous tooth dimensions of a recent archaeological sample of 37 boys, 18 girls and 88 children of unknown sex from London were measured. Mesiodistal (maximum breadth at the contact point) and buccolingual measurements were recorded. A gradient of size variation was apparent with anterior teeth showing the highest variation and second molars the least. In general, the teeth of the children of Spitalfields were smaller than those of other groups from various archaeological and contemporary populations. Fluctuating asymmetry between left- and right-hand sides was greatest for the lateral incisor. Asymmetry of the mesiodistal dimension of the upper central incisor differed significantly from the buccolingual dimension ( p<0.01). Tooth size in both dimensions was generally larger in boys than in girls. The maxillary lateral incisor displayed significant dimorphism in the mesiodistal dimension ( p<0.05). The second molars (both upper and lower) were less variable and less asymmetrical than the first molars, suggesting that the second molar may be the key tooth of the deciduous molar field.

Accuracy of polyether and addition silicone after long-term immersion disinfection

Statement of problem. Some studies have demonstrated that short-term immersion disinfection does not affect the accuracy of polyether or addition silicone materials. Impressions are often disinfected for longer than recommended time periods. Purpose. This study evaluated these materials after simulating overnight disinfection. Material and methods. Impressions were made of a master model with Extrude Extra material with Extrude Wash addition silicone and Impregum F material in combination with Permadyne Garant polyether material. Nondisinfected impressions served as controls, whereas the disinfected samples were immersed for 18 hours in a full strength 2% acid glutaraldehyde solution. Anteroposterior and cross arch dimensions of the working cast and occlusogingival, mesiodistal, and buccolingual dimensions of working die were assessed. The data were analyzed with one-way analysis of variance at “alpha” = 0.05. Results. No significant differences were observed for anteroposterior and cross arch dimension when compared with the master model. However, significant differences were found for occlusogingival dimension at 18 hours of disinfection for both materials. The addition silicone 18-hour disinfection group was significantly less accurate in the mesiodistal dimension. Conclusion. Accuracy of both impression materials was adversely affected with 18 hours of immersion disinfection. Long-term (18 hours) immersion disinfection will affect the fit of fixed partial prostheses. (J Prosthet Dent 1997;78:245-9.)

Imaging strategy in dental implantology

Dental implants are becoming popular and its prognosis satisfactory. However, patient selection and adequate placement of the implant are important for a successful result. Radiographic examination is required to assess the exact location of the mandibular canal and the mental foramen, and the floors of the nasal cavity and the maxillary sinus, and the buccolingual dimension of the jaw. The information obtained by imaging may help the surgeon to plan the placement of the dental implant, reducing the risk of injury to the nerve, vessels and cavities. The radiographic methods commonly utilized for this purpose are panoramic radiggraphy, conventional tomography and computed tomography. Panoramic radiography may be the first choice to obtain general information, but tomography may compensate for the poor ability of panoramic radiography to visualize the bucco-lingual dimension of the anatomical landmarks. Furthermore, the digital data obtained from computed tomography could be used for the simulation of implant placement. A control study in imaging should be performed to determine the most efficient strategy, considering the availability of facilities, costs, radiation dose to the patient, and technician's skill.

Tooth crown size and morphology in Turner syndrome.

The aims of this investigation were to analyze permanent tooth crown size and morphology and to perform symmetry analysis between corresponding teeth on the right and the left side. The material comprised 32 Turner syndrome patients aged 7-16.7 years. As controls served 33 normal girls 10.2-16.7 years old. The mesiodistal diameter was significantly reduced for every tooth measured except for the maxillary canine. The buccolingual dimension was reduced only for some teeth. Eleven morphologic traits were defined. Ten of these were identified in the Turner patients; seven occurred in the controls as well, but at a lower frequency. Some of the traits have not been described earlier for this group of patients. There was a significant difference between Turner and control patients both in the number of patients with bilateral tooth asymmetries and in the number of corresponding tooth pairs in the maxilla with bilateral asymmetry. No significant differences were found between the 45X patients and the other karyotypes. Maxillary central incisors showed a surprisingly high relative frequency (38.5%) of bilateral asymmetry.

Role of the mandibular first molar in the development of the supraorbital region in apes and humans

Our previous studies in apes and humans have demonstrated that the development of the supraorbital ridge is a direct consequence of masticatory forces. The smaller the power arm/load arm ratio of the mandible, the greater the force exerted by the temporalis muscle and the larger the supraorbital ridge. The purpose of the present study is to further elucidate the role of the masticatory apparatus, in particular the role of the first mandibular molar. Measurements of the size of the supraorbital ridges in ape skulls and in human skulls from Tuscany, Italy and St. Lawrence Island, Alaska, were determined using parasagittal CAT scans as in our previous studies. For the purpose of this study, the mesio-distal and buccolingual dimensions of the first molar were measured from the actual tooth in all cases. Statistical analysis shows a positive correlation between the mesio-distal dimension of the mandibular first molar and the size of the ridge in humans (r = 0.61, p < 0.005) and in apes (r = 0.79, p < 0.01), which explains much of the variation in the size of the supraorbital ridge, 37% (0.61(2)) in humans and 62% (0.79(2)) in apes. The role of the mandibular first molar differs in humans versus apes because of differences in masticatory mechanics.

Morphometric variables of developing primary mandibular second molars

Morphometric variables of second primary molar crowns from birth to completion were examined and measured. An image analysing technique comprising a photographic camera, a monitor, a computer with appropriate software and a digital caliper was used. Strong correlations were found between the ‘external’ aspect of the crown (mesiobuccal cusp height, mesiodistal and buccolingual dimensions and perimeter), and between all the ‘occlusal’ measurements of the crown, i.e. all the intercusp distances. However, poor correlations were found between the external and internal measurements of the crown such as the mesiobuccal cusp height and mesiobuccal-mesiolingual cusp-tip distance. It was also found that the mesiobuccal cusp serves as the apex of two triangles, the one formed by mesial cusps, and one formed by the distal cusps. The cusps on the mesial portion of the crown (ML, DB) are on a similar radius from the MB cusp, and the cusps on the distal portion are on a similar radius from the MB cusp. The small sample is a limitation but the results suggest a separate and independent pattern and rate of development of the external and the occlusal morphological variables of the tooth crown. Further research is needed on larger samples.

Small primary tooth-crown size in low birthweight children

As part of a longitudinal study of dental development in a group of low birth-weight children (LBW), study models of 72 children at age 7 years were measured to determine the tooth-crown size of primary molars and canines and to compare the findings with equivalent measurements in 60 normal birthweight (NBW) controls. Mesiodistal (length) and buccolingual (width) dimensions were measured manually, using dial calipers. Primary canines and molars were smaller in the LBW than the controls, with significance values ranging from P < 0.001 for the mesiodistal dimension of maxillary and mandibular canine (> 4% difference) to a non-significant difference P < 0.2 for the buccolingual dimension mandibular first primary molar (1.8% difference). Within the LBW group there was a positive correlation between birthweight and mesiodistal tooth size. Small primary tooth size in LBW children may be influenced by both genetic and environmental factors. The shorter prenatal growth period and poor perinatal and early postnatal development may influence the developing deciduous dentition. Small primary tooth-crown size, associated with LBW, should be considered in all population studies of tooth size.

The Atapuerca dental remains. New evidence (1987-1991 excavations) and interpretations

Abstract The metrical features and some morphological traits of 133 permanent teeth from the site Sima de los Huesos (Sierra de Atapuerca, Burgos, Spain) are analysed and compared with those of other hominid samples. Since the sample sizes were greater for the lower than for the upper teeth, the main conclusions are fundamentally based on the analysis of the mandibular dentition. As an extreme case of the mosaic evolutionary pattern which characterizes hominid dental evolution, the Atapuerca lower dentition shows a strong imbalance between the size of the anterior (I1-P3) and posterior (P4-M3) teeth in relation to modern humans, and even with regard to other middle Pleistocene hominids and the Neandertals. On the average, the dimensions of the Atapuerca mandibular posterior teeth are similar to those of modern humans. Probably very much related to this, the hypoconulid was frequently absent in the lower molars. These observations imply that the selective pressures which operated to maintain a certain size of the posterior dentition during the middle Pleistocene were less restrictive than is assumed by previous evolutionary models. The dimensions of the Atapuerca lower and upper anterior teeth are also small in relation to the middle Pleistocene specimens and Krapina, but they are comparable to those of the late Pleistocene Neandertals, and there is certain expansion of the buccolingual dimensions of the upper lateral incisors with regard to early Homo . The anterior/posterior size pattern of variability observed in Atapuerca is discussed in terms of the different selective pressures which presumably operated over the anterior and posterior segments of the dentition. The multivariate tooth shape analysis indicates a relatively close relationship between Atapuerca and the Neandertals, though some significant differences between them were observed. The limited European middle Pleistocene dental fossil record does not permit a rigorous study of the relationships between Atapuerca and other European middle Pleistocene populations. However, the present evidence suggests that Atapuerca had an unique and probably derived pattern regarding dental dimensions. Furthermore, a great shape dissimilarity has been observed between Atapuerca and Zhoukoudian, which is mainly due to the anterior/posterior tooth size differences between both samples.

Crown size variability in the deciduous dentition of South Australian children.

Although many studies of the permanent dentition have been published, there are still relatively few reports relating to variability within the deciduous dentition. The aim of this study was to provide a detailed description of crown size variability in the deciduous dentition of South Australian children. Dental impressions were obtained of 160 children, 3-6 years of age, and stone models constructed. Mesiodistal and buccolingual crown diameters were recorded from the dental models using a computerized data acquisition system. Several aspects of deciduous tooth size were studied, including variation within and between dental arches, sexual dimorphism, and correlations within and between crown diameters. Principal components analysis was used to summarize the inter-correlated tooth size data and to facilitate the biological interpretation of common variability. The magnitude and pattern of mean values for deciduous tooth size were similar in South Australian children to published data for other Caucasian populations. Although mean values for tooth size were generally larger in boys than in girls, sexual dimorphism in deciduous tooth size was low. Correlation analyses indicated low to moderate associations for size between teeth in the same arch, with highest values between the molars. In both sexes there was a tendency for correlations between buccolingual dimensions to exceed those between mesiodistal dimensions. Although distinct morphogenetic fields have not been defined in the deciduous dentition, there appeared to be a gradient of decreasing size variability from anterior to posterior, with the second deciduous molar being particularly stable. The observed pattern of phenotypic variation appeared to be directly related to the relative length of the developmental period that tooth crowns spent in the soft tissue stage prior to calcification. Multivariate analyses confirmed some overall coordination for crown size of deciduous teeth, but also highlighted specific size patterning related to incisor, canine, and molar regions. © 1993 Wiley-Liss, Inc.

Changes in lower third molar position in the young adult

Changes in position of unerupted lower third molars between 18 and 21 years were examined in a group of 17 men and 24 women with intact lower arches. Mesiodistal third molar angulation, molar space, molar space condition, and buccolingual third molar angulation and the changes in these dimensions were measured on 60 degree cephalograms taken at 18 and 21 years. At 18 years molar space was inadequate by an average of 5.0 mm. Average changes in dimensions were statistically nonsignificant except for an increase in molar space of 0.7 mm. Changes in third molar position ranged from 39 degrees to -46 degrees in the mesiodistal and from 24 degrees to -24 degrees in the buccolingual dimension. Only 10 third molars did not change their mesiodistal angulation. Four third molars erupted fully during the observation period.

The accuracy of polyvinyl siloxane impressions made with standard and reinforced stock trays

A laboratory investigation was done to assess the influence of proprietary stock trays on the accuracy of impressions recorded with heavy light-body (HL) and putty light-body (PL) wash impression techniques. Two brands of trays were tested and the same trays were reinforced with acrylic resin. Individual die accuracy and overall distortion of the resultant casts were assessed. PL impressions in both stock trays gave undersized buccolingual dimensions at the preparation finishing lines whereas reinforcing the trays reduced this distortion. Significant inaccuracy at the second molar was found for all trays when PL impressions were made. These distortions would have resulted in clinically unacceptable dies. HL impressions, regardless of tray type, produced highly accurate dies at this critical site. Resultant overall cast distortion was reduced, but not eliminated, by using reinforced trays with either PL or HL techniques.

Cross-sectional radiography for implant site assessment

An accurate tomographic technique is described for acquisition of optimal cross-sectional images of implant sites before implant surgery. The described technique is applicable to tomographic systems equipped with a cephalometric head positioner. This cross-sectional tomographic technique was performed on a series of patients and the images of the first 20 patients subsequently evaluated. The cross-sectional images allowed for the characterization of the alveolar crest and visualization of anatomic structures in a buccolingual dimension while providing an accurate estimation of available vertical space from the crest.