Replacement of missing mandibular lateral incisors with a single pontic all-ceramic prosthesis: a case report

The conventional approach for replacing congenitally missing mandibular lateral incisors dictates the placement of either a conventional porcelain-fused-to-metal (PFM) bridge, Maryland bridge, or fiber-reinforced composite veneer bridge. However, several appearance-related disadvantages have been reported in the use of a prosthesis which incorporates a metal substructure. To address these limitations, metal-free restorative alternatives have been recently developed to expand the clinical options when fabrication of these prostheses is indicated. The learning objective of this article is to present the utilization of a single pontic all-ceramic resin-bonded bridge to replace congenitally missing mandibular lateral incisors, where the existing mesiodistal spaces were narrow and the abutment teeth exhibited insufficient substance for the conventional treatment modality.     

The use of cantilever bridges

Replacement of missing teeth with fixed bridgework often involves producing full crown retainers on teeth on both sides of an edentulous space. Unfortunately, this approach can result in the destruction of much healthy tooth tissue, and the clinician must balance the benefits of replacing missing teeth with the amount of tooth preparation required. Current thinking in restorative dentistry places the preservation of tooth tissue at a premium, and most practitioners are happy to use techniques that embrace this philosophy. Because of this, cantilever bridges have an increasing role in dental practice, where the replacement for a missing tooth or teeth has one or more abutments on only one side of the edentulous space, being unsupported at the other. Cantilever bridges fall into several types, depending on the number of abutments and types of retainers. This article describes the various cantilever bridge designs, considers the biomechanics of these restorations, and provides guidelines for their clinical use.     

Hypodontia of primary and permanent teeth in a sample of Saudi children

Hypodontia, congenitally missing teeth is more common in permanent than primary dentition. The present investigation reports the prevalence and pattern of hypodontia in the primary and permanent dentitions, excluding third molars in a sample of Saudi children. The sample consists of 1,300 children, aged 5 to 10 years of age. Clinical and radiographic examinations were performed. The prevalence of children with hypodontia was found to be 2.6 percent. The mandibular second premolar was the tooth most frequently absent and account for 45 percent of the total missing teeth. In primary dentition, the maxillary lateral incisor was the tooth most frequently absent (9%). A peg-shaped permanent maxillary lateral incisor was present in 0.7 percent of the sample. Congenitally missing teeth were almost equally distributed between maxillary (52%) and mandibular (48%) arches.     

Fixed prosthodontic replacement of single incisors in three dogs

Three dogs each received a three-unit fixed-fixed porcelain-veneer bridge for the replacement of traumatically-lost upper first or second incisor teeth. The bridges remained in place for a period ranging from 6-36 months, before becoming dislodged as a result of external trauma. It was concluded that this type of bridgework is technically feasible and may be justifiable.     

Risk factors and multiple failures in posterior resin-bonded bridges in a 5-year multi-practice clinical trial

OBJECTIVES: A randomized controlled clinical trial was undertaken, to study the influence of some patient- and operator-dependent variables on the survival of posterior resin-bonded bridges (PRBBs) and to assess the survival of replacement' PRBBs. This report contains some of the results of the 5-year analysis. METHODS: Survival was defined at three levels: (1) complete survival (without any debonding), (2) functional survival (i.e. survival after one loss of retention) and (3) replacement survival (survival of 'replacement' PRBBs, inserted after rebonded bridges suffered a second dislodgement). Potential risk factors were analysed with Cox's proportional hazards model and differences were tested for significance with the Breslow test. Observed effects are expressed as conditional-relative-risk (CRR). Survival of 'replacement' PRBBs was assessed with the Kaplan-Meier method. RESULTS: Factors showing significant influences on complete survival were: 'location' (highest risk for mandibular PRBBs: CRR = 2.2), 'aetiology' (higher risk in treatment of aplasia: CRR = 2.9), and 'time of existence' (open spaces existing less than 2 years before insertion of PRBB: CRR: 2.0). The factor 'large open spaces in the mandible' was a risk for both complete and functional survival (CCR values 3.1 and 3.5, respectively). The survival of mandibular and maxillary 'replacement' PRBBs after 5 years was 19 +/- 7% and 31 +/- 18%, respectively. CONCLUSIONS: Risk factors for PRBBs were: 'location', 'aetiology', 'time of existence', 'isolation method' and 'large open spaces in the mandible'. Mandibular 'replacement' PRBBs showed such an unacceptably low survival rate that fabrication is not recommended.     

Sex determination with a discriminant function analysis of deciduous teeth size in plaster models

Plaster models of the teeth of 3-year-old Japanese children (96 males, 98 females) were used to record the crown length, crown width and crown thickness of 5 maxillary and 5 mandibular deciduous teeth (30 measurement values). These measurements were used to devise a number of sex determination formulae. A sex-determination formula using all 30 values was calculated. Furthermore, a number of practical formulae were derived from only the crown width and crown thickness values because the deciduous teeth wear in 4 years and older children rapidly progress, making the crown length measurement unreliable. These formulae were calculated for the maxillary teeth alone and mandibular teeth alone. The formulae based on only the crown width or thickness were also calculated for both maxillary and the mandibular teeth. A step-wise discriminant analysis was then used to ascertain the most reliable measurements and a practical formula subsequently devised. The results obtained were as follows: 1. The mean value for each measurement was greater in males than in females. 2. Significant differences in the values recorded were seen in 28 out of the 30 measurements taken. The measurement items not exhibiting these significant differences were the crown width of the maxillary lateral incisor and the crown thickness of the mandibular second molar. 3. The accuracy rates for the sex-determination analysis and the step-wise sex determination analysis calculated using all 30 values were 78.6% and 75.7%, respectively. 4. The accuracy ranges for the modified sex-determination formulae and the associated step-wise sex determination analyses were 70.6-78.4% and 67.0-76.8%, respectively.     

Development of the Vertical Lift Bridge: Squire Whipple to J. A. L. Waddell, 1872–1917

The development of canals started in the mid 18th century in England and Europe and in the 1820s in the United States. They required the design and construction of many bridges to provide canal crossings for carriages, wagons, animal herds, and pedestrians. The cost of building bridges of masonry or wood to carry roadway traffic high over the towpaths and waterways of canals was very great so engineers of the day developed bridges that could be moved out of the way when a canal boat was coming through and then moved back over the canal to provide roadway access. The Dutch developed a type of bascule bridge for many canals, while the British developed swing or pull back bridges. The swing bridge for narrow canals had a turntable on shore with a short counterweight span over land and a cantilever span over the canal. This bridge could be worked by hand with a simple crank. The pull back bridges, while not as common, ran on tracks and had the same type of counterweight span and cantilever span over the canal. On wide canals, as well as on the C & O Canal in the 1830s, the swing bridges had a central pier on which the turntable was mounted and the bridge cantilevered out on both sides to the shore when closed, and frequently onto an extended pier parallel to the canal when the bridge was open for canal boat passage. In the United States the most common bridge on canals and waterways was a side mounted or center mounted swing bridge well into the 20th century. The development of the metal vertical lift bridge can be traced to the late 1840s in England where several small lift spans were built. After a review of early European spans, this paper covers the period starting in 1872 with Squire Whipple and his Erie Canal bridges, and terminates in 1917 with Waddell’s Columbia River Bridge.     

Anesthetic efficacy of the supplemental intraosseous injection of 2% lidocaine with 1:100,000 epinephrine in irreversible pulpitis

The purpose of this study was to determine the anesthetic efficacy of a supplemental intraosseous injection of 2% lidocaine with 1:100,000 epinephrine in teeth diagnosed with irreversible pulpitis. Fifty-one patients with symptomatic, vital maxillary, and mandibular posterior teeth diagnosed with irreversible pulpitis received conventional infiltrations or inferior alveolar nerve blocks. Pulp testing was used to determine pulpal anesthesia after "clinically successful" injections. Patients who were positive to the pulp tests, or were negative to the pulp tests but felt pain during endodontic access, received an intraosseous injection using 1.8 ml of 2% lidocaine with 1:100,000 epinephrine. The results demonstrated that 42% of the patients who tested negative to the pulp tests reported pain during treatment and required supplemental anesthesia. Eighty-one percent of the mandibular teeth and 12% of maxillary teeth required an intraosseous injection due to failure to gain pulpal anesthesia. Overall, the Stabident intraosseous injection was found to be 88% successful in gaining total pulpal anesthesia for endodontic therapy. We concluded that, for posterior teeth diagnosed with irreversible pulpitis, the supplemental intraosseous injection of 2% lidocaine (1:100,000 epinephrine) was successful when conventional techniques failed.     

A case of anastomotic aneurysm-enteric fistula

Reimplantation failure of avulsed anterior teeth in an adolescent patient requires removal of the attempted-reimplanted teeth and consideration of several restorative options. These options may include a removable partial denture, as well as a transitional bridge or permanent fixed prosthesis. In all cases, the potential effects of the adolescent's expected amount and directions of maxillary and mandibular growth must be considered. A case is presented examining how maxillary growth may affect the restorative treatment options for avulsed anterior teeth replacement for an adolescent boy. Unfortunately, the patient and family were unable to complete treatment due to financial considerations. Consequently, the case presented here is submitted as a treatment planning exercise.     

Sexual transmission of GB virus C/hepatitis G virus

Tooth transposition is a positional interchange of two adjacent teeth. The most commonly transposed tooth is the permanent canine with either the first premolar or lateral incisor. The records of 54 subjects with transposed canines, both maxillary and mandibular, were collected. Pretreatment study models of these subjects were matched with a similar number of models from unaffected individuals. Bucco-lingual and mesio-distal tooth widths, arch depth and arch width were measured on each model. Thirty-four subjects (63 per cent) were female. Thirty-seven (68.5 per cent) of the cases involved the maxillary arch and thirty-three (89.2 per cent) of these upper arch transpositions were of the canine and first premolar. In cases involving the lower arch the canine was invariably transposed with the lateral incisor. Peg-shaped lateral incisors, supernumerary and/or congenitally absent teeth occurred in 19 subjects. There were some small, but significant differences in the dimensions of some teeth, however there were no statistically significant differences in arch depths, arch widths and most tooth dimensions in subjects with and without transposed canines. These factors do not appear to be related to the development of canine transposition.     

Sealing ability of several restorative materials used for repair of lateral root perforations

Amalgam, IRM, Vitremer, Bisfil, and Ana Norm Liner were evaluated for repair of experimentally induced lateral perforations. Eighty-five sound, mandibular, and maxillary molars, extracted for periodontal reasons, were selected for this study. The sample teeth were randomly divided in five groups with 15 specimens each. Ten teeth were used as control groups. After the perforations were filled with the above-mentioned materials, the teeth were immersed in a 2% methylene blue solution for 48 h, sectioned, and dye penetration was measured. The results indicated that Bisfil 2 B provided a significantly better seal than the other materials.     

Fixed bonded prosthodontics: a 10-year follow-up report. Part I: Analytical overview

Developments in biomaterials in the field of adhesion have made possible a less invasive dentistry. Improvements in adhesive polymers along with the analysis of certain failures in resin-bonded prostheses have suggested the micropreparation of abutment teeth. A long-term study of resin-bonded prostheses and splints was undertaken. The success rate of this protocol is presented for a study period of 10 years (1984 to 1993). These results indicated that the resin-bonded prosthesis is a viable option in patients who are missing one or two teeth. Of 145 prostheses, 11 failed, resulting in an overall survival rate of 83% (Kaplan-Meier test). Furthermore, the study confirmed that, for splints, preparation is important to counter the major stresses related to tooth mobility in patients with periodontal disease.     

Influence of Changes in Cross Section on the Effectiveness of Externally Bonded FRP Strengthening

There are many situations where strengthening might be required for a nonprismatic reinforced concrete section (i.e., a beam or slab where the depth of the section varies along its length). For example, many bridges in the United Kingdom have inadequate capacity to carry accidental vehicle loads on verges. These shallow depth verges are often cantilevered from the much deeper main bridge deck. The cantilever might be strengthened by applying fiber-reinforced polymer (FRP) composites to the top surface of the cantilever, extending transversely onto the bridge deck. However, a problem may exist with such a situation due to the potential for a dramatic reduction in the degree of strengthening which is achievable. This is due to the effects of cracking, and longitudinal shear stresses. Tests presented in this paper demonstrate that in regions where little or no cracking occurs, local or global debonding of the external FRP may result. Therefore, the strength of some nonprismatic beams, as predicted by current design guidelines, is often shown to be overly conservative and, in one case significantly unconservative. However, more importantly, the predicted failure modes and FRP strains often do not correspond to those observed. Advice on the best approach for analyzing these beams is given.     

Variation in maxillary and mandibular molar and incisor vertical dimension in 12-year-old subjects with excess, normal, and short lower anterior face height

Maxillary and mandibular molar and incisor vertical dimensions were evaluated in subjects who had excessive, normal, and short lower anterior face height in relation to upper face height. Sexual dimorphism was also investigated. The dentoalveolar heights were compared between Class I and Class II, dental and skeletal malocclusions. The sample was drawn from the Burlington Growth Centre sample and consisted of 188 male and 156 female subjects at age 12 years, for whom lateral head films were available. This sample was classified into excessive, normal, and short lower anterior face height, using the ratio upper anterior face height/lower anterior face height (UAFH/LAFH). The results showed that the dentoalveolar heights are significantly different between faces with excessive, normal, and short lower anterior face heights, except for the lower posterior dental height, which showed no difference between short and normal lower anterior face height subjects. All dentoalveolar heights are larger for male subjects except for the upper posterior dental height. Dentoalveolar heights are similar between Class I and Class II dental and skeletal malocclusions. The upper teeth present a higher correlation to the UAFH/LAFH ratio than the lower teeth. Stepwise regression analysis shows that 22% of the variation in the ratio is explained by the maxillary and mandibular molars and 41% is explained by the maxillary and mandibular incisors.     

Maturation alters the contractile role of calcium in ovine basilar arteries

OBJECTIVE: To investigate the distribution patterns of primary and permanent teeth in the cleft area and the numerical variation in teeth in unilateral complete cleft lip and palate (UCLP) patients. DESIGN: A survey of the dentition in UCLP patients. SETTING: Craniofacial Center, Chang Gung Memorial Hospital, Taipei, Taiwan. PATIENTS: 137 UCLP patients who met the following criteria: (1) have had at least one panoramic film taken, (2) the first panoramic film illustrates either primary or early mixed dentition. Evaluation of both permanent and primary dentition was available in 91 cases. MAIN OUTCOME MEASURES: Two evaluators performed independent evaluations of number and distribution of teeth in UCLP patients. The hypothesis that there are two odontogenic origins for maxillary lateral incisors was proposed to explain the occurrence of distribution patterns of dentition in the cleft area and to explain differences between primary and permanent dentition in UCLP patients. RESULTS: Four distribution patterns in the cleft area were identified in both the primary and the permanent dentition. In the primary dentition, placement of the lateral incisor distal to the alveolar cleft was the predominant pattern (pattern y, 82.4%), followed by absence of the cleft side maxillary lateral incisor (pattern ab, 9.9%), presence of one tooth on each side of the alveolar cleft (pattern xy, 5.5%), and placement of the lateral incisor mesial to the alveolar cleft (pattern x, 2.2%). In the permanent dentition, the most common pattern was the absence of the maxillary lateral incisor on the cleft side (pattern AB, 51.8%), followed by lateral incisor placement distal to the alveolar cleft (pattern Y, 46%), lateral incisor placement mesial to the alveolar cleft (pattern X, 1.5%) and the presence of one tooth on each side of the alveolar cleft (pattern XY, 0.7%). The discrepancy between the distribution patterns of primary dentition and permanent dentition successors is 57.1%. Variations in tooth number in both primary and permanent dentition of UCLP patients occurred most often in the cleft area. Abnormalities in the number of teeth (hypodontia or hyperdontia) outside the cleft area were more common in the permanent dentition than in the primary dentition (24.1% versus 4.4%). CONCLUSIONS: Four distribution patterns in the cleft area were identified in both sets of dentition. Our findings of distribution patterns in UCLP patients support the hypothesis that there may be two odontogenic origins for maxillary lateral incisors. Clinicians involved in managing the dentition of UCLP patients should consider the high frequency of numerical variation both in and outside the cleft area before starting dental treatment.     

A study of anterior guidance

PURPOSE: This study focuses on the curvature and inclination of the lingual surfaces of the maxillary anterior teeth from the transition point on the cingulum to the incisal edge. MATERIALS AND METHODS: On 32 sets of mounted casts, 768 measurements were made of the curvature of the lingual surfaces utilizing radius gauges. The inclination of the lingual surface relative to the occlusal plane was recorded. The relationship of the incisal edge of the mandibular teeth to the transition point on the cingulum of the maxillary teeth was determined. Centric occlusion contact was noted on each tooth. RESULTS: Significant differences were found between the measured areas of any one tooth and between the types of teeth. The average radius ranged from 20.5 mm on the mesial ridge of the canine to 5.3 mm in the fossa of the central. The average inclination of the lingual surfaces was 46 degrees. In centric occlusion, 97% of the canines and 59% of the centrals and laterals were in contact with the opposing teeth. These contacts occurred 2.8 mm incisal to the transition point. The centrals contracted two opposing teeth (45%), and canines contacted one opposing tooth (53%). CONCLUSIONS: The function and curvature of the incisor teeth vary considerably from those of the canines. Overcontouring the lingual surfaces of the maxillary incisors to gain contact is not normal and may be detrimental.     

Kentucky River High Bridge

Cantilever bridge construction can be said to have started with the work of Heinrich Gerber in Germany in 1867. While the principle had been used in many ancient bridges, it was not until Gerber’s work that metal bridges were built using the cantilever principle. The Kentucky High Bridge over the Kentucky River was the first modern cantilever bridge built in the United States. While James Eads had used the cantilever construction method at St. Louis, his bridge acted in service as a series of three arches. The High Bridge, designed by C. Shaler Smith, was one of the most daring and innovative bridges built in the country and carried its load between 1876 and 1912, when it was replaced by Gustave Lindenthal’s three span truss.     

Examination of the degree of agreement among dental findings used for personal identification (report 5)--canonical correlation between dental findings on dental charts and those on radiographs

Findings obtained from dental charts and from radiograph taken one year later for the same individuals were examined and classified according to different criteria. Similarities between the two sources investigated by the canonical correlation method. The results obtained were as follows: 1. The correlation coefficient and the squared multiple correlations (R2) were calculated. Consequently, high similarities were seen between the two sources for the mandibular anterior teeth [sequence: see text], maxillary incisor teeth [sequence: see text], mandibular and maxillary first premolar teeth [sequence: see text], and the corresponding teeth of the same jaws. 2. Three roots showed high elucidative values by the canonical correlation method. The first root was understood to be the mandibular incisor factor, the second the maxillary incisor factor, and the third the first premolar factor. This seemed to indicate, that the similarities between the two sources in these regions were very high. 3. A study of the similarities between the two sources was done based on the individual scores of canonical variable loadings calculated in this analysis. High similarities were seen at [sequence: see text] in category 1 (intact & C1) for chart findings and category 1'(intact, C1-C3 & resin filling) for radiographic findings: at [sequence: see text] in category 2 (C2-C4, inlay & filling of repair) for chart findings and category 3'(stump of tooth) for radiographic findings; and at [sequence: see text] in category 3 (complete crown, jacket crown & post crown) for chart findings and category 3'(stump of tooth) for radiographic findings. 4. The present results suggest that if proper case in taken, one set of information can serve as a substitute for the other. In personal identification, higher efficiency may be achieved if this is borne in mind.     

Peer approaches for increasing HIV awareness on a college campus

PURPOSE: To compare the accuracy of clinical examination performed with bitewing radiographs or clinical examination using tooth separation to identify carious lesion activity. MATERIALS AND METHODS: 320 surfaces from 40 bitewing radiographs were examined for approximal caries on the maxillary and mandibular primary molars of 20 patients 3-10 years old. The patients were divided into three groups: (1) Absence of the permanent first molar; (2) Partial eruption of the permanent first molar; and (3) Full eruption of the permanent first molar. Two examiners evaluated the radiographs using a megascope, a magnifying glass (x2), and an amplifying image screen. Approximal radiolucencies were identified on 72 surfaces. Following the radiographic examinations, the two examiners performed conventional clinical inspection using a No. 4 dental mirror, a No. 5 dental explorer, and an air-water syringe, with artificial light and relative isolation. The separation method was performed with elastic bands, which were removed after 24 hours, and the clinical examination conducted as in the non-separation group. RESULTS: The correlation between the extension of interproximal radiolucent lesions in primary dentition and their clinical diagnoses following separation of the teeth, was similar to findings on literature evaluating the permanent dentition. On radiographic findings for enamel lesions, white spots predominated both in the inner (100%) and in the outer (94%) half of enamel upon clinical examination with separation of teeth. For radiolucent lesions in dentin, on the other hand, cavities predominated over white spot lesions (84%). In Groups 1 and 2 (young primary), white spots occurred in cases where the radiolucent lesions reached the dentin (15% and 25%), similar to findings for young permanent teeth. Clinical diagnosis performed with the mechanical separation of teeth cannot be considered conclusive for the primary dentition.     

Long-term follow-up on hydroxylapatite-coated cylindrical dental implants: a comparison between developmental and recent periods

PURPOSE: To compare success rates for dental implants placed from 1985 through 1988 and from 1989 through 1991, and to investigate the factors associated with success or failure. PATIENTS AND METHODS: All hydroxylapatite-coated cylindrical implants placed from 1985 through 1991 were followed yearly. Lifetable survival analyses compared implant success for a "developmental period" from 1985 through 1988 (4 to 8 years follow-up) and a "recent period" from 1989 through 1991 (1 to 4 years follow-up). Reasons for success or failure, time from implant placement to removal related to failure reason, outcome after implant removal, and a morbidity analysis are included. RESULTS: The 7 to 8-year cumulative success rate for all implants placed in the developmental period (maxilla and mandible combined) was 86.5%; it was 84.2% for all maxillary implants and 87.5% for all mandibular implants. The cumulative success rate for all implants placed in the recent period was 97.5%; it was 97.5% for all maxillary implants and 97.6% for all mandibular implants. The difference between the two periods was statistically significant only for the anterior maxilla. Regression analysis on the interval success rates indicates that interval failure did not follow a linear relationship with time. The most common reasons associated with failure were lack of keratinized gingiva, poor oral hygiene, mechanical overload, and malposition. CONCLUSION: Comparison with previously reported cumulative success rates indicated learning curve experiences comparable with other implant systems. Improvements in hardware, surgical and prosthetic techniques, and patient selection have led to an improvement in success rates with the recent period implants.