Medical knowledge | Dentistry » Banoo-Robin-John - A study of the use of photographs

Banoo Bindra, BDS, MSc, FDS RCS Eda Robin M. Basker, DDS, MGDSRCS, FDSRCS Edb John N. Besford, BDS, PhD, MFGDP (UK)c A Study of the Use of Photographs for Denture Tooth Selection Purpose: The aim was to examine a method described by Wehner et al for calculating the width of a missing central incisor using preextraction photographs. Materials and Methods: Three photographic views were obtained for each of 30 dentate subjects: full face, oblique, and reduced-size full face. The width of the maxillary right central incisor (MR1) was calculated using a formula. The difference between the actual width and calculated width of MR1 was determined for each subject. The median difference and interquartile range were determined because the data were skewed. Results: The width of MR1 calculated using the larger full-face view was typically smaller than the actual width, with a median difference of –0.18 mm The interquartile range of the difference was from –0.42 to 005 mm For both the

oblique and reduced-size views, the calculated width was typically larger, with a median difference of 1.19 mm with an interquartile range from 0.82 to 176 mm and a median difference of 084 mm with an interquartile range from 0.59 to 141 mm, respectively Conclusion: The technique described by Wehner et al is of proven value in calculating the width of a central incisor when the only available evidence is a preextraction photograph. However, it is of value only when the photograph is a full-face portrait of sufficient size. Int J Prosthodont 2001;14:173–177 P roviding artificial maxillary anterior teeth that closely resemble the patient’s missing natural teeth can pose a significant challenge to the dentist, particularly when treatment is sought by patients with extensive tooth loss such that guidance cannot be obtained from the remaining natural teeth. Increasing esthetic awareness and expectations of patients may make this challenge more frequent. Pound1 stated that five

factorstooth size, form, color, arrangement, and the framing of the teeth must harmonize to achieve optimal facial appearance. Wehner et al2 describe the work of House and Loop,3 wherein anthropometric data were used in the selection of artificial teeth. In their study of 555 dentate subjects, it was found that the greatest bizygomatic width of the skull divided by 16 gave an approximation of the width of the maxillary central incisor, and when divided by 3.3 gave an estimated width of the six maxillary anterior teeth when arranged flat on a card. They also described a method of calculating the width of a central incisor by measurements made on a preextraction photograph and on the patient and substituting in the following equation: aSpecialist Registrar in Restorative Dentistry, Leeds Dental Institute, United Kingdom. bProfessor of Prosthetic Dentistry, Leeds Dental Institute, United Kingdom. cSpecialist Practitioner, London, United Kingdom. Reprint requests: Dr B. Bindra,

Department of Restorative Dentistry, Leeds Dental Institute, Clarendon Way, Leeds LS2 9LU, United Kingdom. Fax: + 44 113 2336129 e-mail: banoo@bigfootcom This study was presented as a poster presentation at the British Society for the Study of Prosthetic Dentistry’s Annual Scientific Meeting, March 1999, Liverpool, United Kingdom. Volume 14, Number 2, 2001 173 The International Journal of Prosthodontics Use of Photographs for Denture Tooth Selection Bindra et al Fig 1 (left) Full-face view of subject (originally 5  7 inches). Fig 2 (below left) Oblique view of subject with head turned approximately 30 degrees to the left (originally 5  7 inches). Fig 3 (below) Reduced-size full-face view of subject shows the head, neck, and upper body (originally 5  3 inches). Calculated Photographic width MR1  actual PD = width MR1 Photographic PD Materials and Methods The authors obtained ethical approval from the local ethics committee for this study involving a statistically

determined sample size of 30 adult dentate subjects. Calculation of the study sample size was based on detection of differences of 0.25 mm at a 5% significance level and 95% power. Two color photographs of 5  7 inches each were obtained for each subject. These showed the full face only, in an anterior view (Fig 1) and in an oblique view approximately 30 degrees to the left (Fig 2). A third color photograph of 5  3 inches was obtained, showing the head, neck, and upper body (Fig 3). The width of the head in the third photograph was approximately one fifth that in the larger full-face view. All were taken by the same photographer using predetermined camera settings. Subjects in whom the entire width of where MR1 is the maxillary right central incisor and PD is the interpupillary distance. Besford4 also drew attention to the value of photographs and noted that the production of good-quality prints had become increasingly common. The various methods that have been described to aid

artificial tooth selection have been reviewed by Sellen et al.5 Few of them appear to have been validated by scientific research. This study aimed to (1) examine the reliability and usefulness of the method described by Wehner et al2; (2) study the effect of photograph size and view on the accuracy of the method; and (3) find out whether using magnifying loupes makes the measurements of the photographs more accurate. The International Journal of Prosthodontics 174 Volume 14, Number 2, 2001 Bindra et al Use of Photographs for Denture Tooth Selection the right central incisor was not visible, for example owing to overlapped teeth, were excluded from the study. The width of MR1 and the interiris distance on the photographs were measured with a ruler to the nearest 0.25 mm The interiris distance was measured from the most medial point of one iris to the most medial point of the other. This distance, rather than the interpupillary distance, was measured, as it was more accurately

identified on the photographs. For the clinical measurement of the interiris distance, the subject and investigator faced each other. The medial margin of each iris was marked on a wooden tongue spatula, and the distance was measured using the ruler. When making the mark for the subject’s right eye, the subject was asked to look at the investigator’s left eye and vice versa. This eliminates the convergence of the pupils when focusing on a close object. All measurements on photographs were made using magnifying loupes with 2.5 magnification Those of the subjects’ teeth and of the distance between the marks on the spatula were made with the naked eye. For a subgroup of 12 subjects, the measurements on the larger full-face photographs were repeated without use of magnifying loupes, and the data were compared. Three readings were obtained for each measurement, and a mean was calculated. Repeat readings on the same subject/photograph were made at different times to avoid memory bias.

To calculate the width of MR1, the measurements were substituted in the following equation: Table 1 Calculated Photographic width MR1  actual ID = width MR1 Photographic ID The intraoperator variability was assessed and judged to be within acceptable limits. The standard deviation was found to be well within clinically relevant values (Table 1). The results for the three photographic views are shown in Fig 4. The width of MR1 calculated using the larger full-face view was typically smaller than the actual width, with a median difference of –0.18 mm The interquartile range (where 50% of the readings lie) of the difference was from –0.42 to 005 mm Ninety percent of the readings lay within a range from 0.95 mm smaller than the actual width of MR1 to 018 mm larger. Using this view, there was a greater tendency to underestimate the width of the tooth than to overestimate it. For the oblique view, the calculated width was typically greater than the actual width of MR1, with a median

difference of 1.19 mm; the interquartile range of the differences was from 0.82 to 176 mm The median difference between the calculated and actual width of MR1 for the reduced-size photograph Parameter measured (mm) Mean Standard deviation 7.7 48.3 6.7 44.4 0.1 0.6 0.1 0.1 Width of MR1 on subject Interiris distance on subject Width of MR1 on larger full-face view Interiris distance on larger full-face view MR1 = maxillary right central incisor. 3 2.45 2.5 2.08 Difference (mm) 2.0 1.76 1.5 1.19 1.0 0.82 0.5 0.0 0.18 0.05 –0.5 –0.42 –0.18 –1.0 –0.01 1.41 0.84 0.59 0.18 –0.95 –1.5 Full face Oblique Reduced Photographic view Fig 4 Box-and-whisker plots show the median and interquartile range for the difference between the actual and calculated width of the maxillary right central incisor for each of the three photographic views (n = 30). Results where ID is the interiris distance. After this calculation was completed, the maximum width of MR1 for

each subject was measured directly with a digital caliper (Kennedy Tools). For each of the three photographic views, the calculated width of MR1 was compared with the actual clinical width of MR1. The difference between the two values was determined for each of the 30 subjects. The median difference and interquartile range were determined because the data were skewed. All measurements were made by the same investigator. Intraoperator variability was assessed for both clinical and photographic measurements. Three measurements of the width of MR1 and the interiris distance of one subject and their photograph were obtained on ten different occasions, totaling 30 readings for each parameter. The mean and standard deviation were determined. Volume 14, Number 2, 2001 Assessment of Intraoperator Variability 175 The International Journal of Prosthodontics Use of Photographs for Denture Tooth Selection Table 2 Bindra et al view are available; hence, the method was tested on two

different photograph sizes and views. The interiris distance was used, as it is a relatively constant dimension, with little change after the cranial base has reached its full size in adulthood. Some means of measuring the patient’s interiris distance is required; a wooden tongue spatula was used in this study to mark the points, and the distance between them was then measured with a ruler. Special devices used by opticians are also available but are expensive. Pointed dividers, although readily available in most dental surgeries, are potentially dangerous and should be avoided. Measuring one central incisor as opposed to both central incisors (as suggested by Besford4) probably increases the error slightly, but it allows the method to be used when the teeth are spaced or overlapped. The results did not indicate an advantage in the use of magnifying loupes; however, owing to the small sample size for this subgroup, it is likely that very small differences would not be revealed. The

clinical relevance of the technique investigated in this study can be inferred from Table 2. For example, if the clinician would be satisfied with a calculated result that would provide a central incisor that was ± 0.5 mm of the patient’s natural tooth, the fullface view of the size used here would be acceptable in 90% of cases. If greater accuracy were sought (± 0.25 mm), it would be possible in 63% of cases The oblique view is clearly of very little clinical value, and the reduced-size view is little better. Thus, in a clinical situation, a patient may present with missing maxillary anterior teeth or be edentulous, but they may be able to provide a preextraction photograph. This could then be used to select a maxillary central incisor tooth that resembles closely the missing natural tooth both in size and form. The ratio of the true and photographic interiris distance allows one to scale the photograph and enables calculation of the true central incisor width. Most mold charts

available for selecting artificial teeth print the width of the central incisor for a group of anterior teeth. The dentist can then select the group closest to the calculated width of the central incisor and also use the photograph to provide an indication of tooth shape. Clinical Relevance of Results View Larger full face Oblique Reduced-size full face % within ± 0.25 mm % within ± 0.5 mm % within ± 1 mm 63 0 7 90 3 20 97 37 57 Table 3 Median and Interquartile Range (mm) of the Difference Between the Calculated and True Widths for the Full-Face Photograph (n = 12) Without magnification With magnification 25th percentile Median 75th percentile –0.17 –0.24 –0.03 –0.11 0.18 0.05 was 0.84 mm, the calculated width being typically larger. The interquartile range of the differences ranged from 0.59 to 141 mm For both the oblique and reduced-size views, there was a marked tendency to overestimate the width of the tooth. The errors were also larger than for the

fullface view The percentage of readings for each view that fell within a range of ± 0.25 mm, ± 05 mm, and ± 1 mm when compared with the actual clinically measured tooth width is shown in Table 2. Comparison of the data obtained with and without the use of magnifying loupes did not reveal a difference between the two techniques (Table 3). Discussion The most appropriate length of an artificial tooth is determined by various factors, mainly esthetic considerations related to the desired amount of tooth display. Tooth wear and gingival recession may change the length of the clinical crown, while lip length and skeletal pattern will affect the length of tooth displayed during functional activities. Both lengths are therefore variable. However, the width of an anterior tooth is at least as important as the length, as it helps to establish the visual mass of the tooth and, barring accidents, is more constant than the length. The results of this study indicate that preextraction

photographs are capable of providing a guide to the selection of denture tooth width; however, their usefulness is dependent upon the size and view of the photograph available. For the method to be of acceptable accuracy, the photograph must be in focus, with the maxillary central incisor visible and the eyes open sufficiently to show their structure. Often, only small sizes or views other than the frontal full-face The International Journal of Prosthodontics Conclusions • Preextraction photographs are capable of providing a guide to the selection of denture tooth width. • The technique described by Wehner et al2 is of proven value in calculating the true width of a central incisor. However, it is of value only when the photograph is a full-face portrait of adequate size. 176 Volume 14, Number 2, 2001 Bindra et al Use of Photographs for Denture Tooth Selection Acknowledgments 2. The authors are grateful for the expertise provided by the Medical and Dental Illustration

Unit of the Leeds Dental Institute, for the statistical assistance provided by Mr Brett Scaife, University of Leeds, and for Mr S. Fayle’s assistance with preparation of Fig 4 3. 4. 5. References 1. Wehner PJ, Hickey JC, Boucher CO. Selection of artificial teeth J Prosthet Dent 1967;18:222–232. House MM, Loop JL. Form and Color Harmony in the Dental Art Whittier, Calif: MM House, 1939. Besford JN. Restoring the appearance of the edentulous person Restorative Dent 1984;1:17–27. Sellen PN, Jagger DC, Harrison A. Methods used to select artificial anterior teeth for the edentulous patient: A historical overview. Int J Prosthodont 1999;12:51–58 Pound E. Applying harmony in selecting and arranging teeth Dent Clin North Am 1962;6:241–258. Literature Abstract Marginal fit and short-term clinical performance of porcelain-veneered CICERO, CEREC, and Procera onlays. The aim of this study was to determine whether the Cicero (Dental Systems), Cerec (Sirona), and Procera (Nobel

Biocare) systems are capable of producing all-ceramic cores veneered with porcelain for an experimental onlay design. The criteria for acceptance were (1) fit for prevention of periodontal disease and caries, (2) esthetics for a pleasing result, and (3) no fracture in function. The material consisted of 15 mandibular and 10 maxillary molars that were prepared for onlays in 17 patients The onlay design was experimental Molars were prepared with deep gingival chamfers in the proximal boxes and around the functional cusps. The nonfunctional cusps were prepared with broad bevels Eight stone dies of preparations were measured with a laser beam (Cicero), ten dies with a light beam (Cerec), and seven dies with a contact probe (Procera). Two onlay cores were produced for the same stone die One core was used to analyze fit on the stone die, and the other core was porcelain veneered for optimizing anatomy, esthetics, and fit of the onlay and cemented. The fit of the onlay core on the stone die

and the cement width on a stone cast were measured by a microscopic digital imaging system. The onlays were evaluated for function every 6 months for 2 years The results showed that the measurements of the margins by the Cicero system were precise and accurate, with a standard deviation of less than 9 µm. The marginal gaps of the Cicero, Cerec, and Procera cores on the stone dies were 74 µm (SD 15 µm), 85 µm (SD 40 µm), and 68 µm (SD 53 µm), respectively. The cement width was 81 µm (SD 64 µm) No fractures occurred It was concluded that marginal gaps for the onlay cores were no more than 85 µm. The 81-µm cement width of the semicomputer-produced onlays was a favorable measurement value for a clinically acceptable, strong all-ceramic onlay. However, this value, as well as anatomy and esthetics of the onlay, depended on the craftsmanship of the porcelain veneering by the dental technician. Denissen H, Dozic A, van der Zel J, van Waas M. J Prosthet Dent 2000;84:506–513

References: 26 Reprints: Dr Harry W. Denissen, Academic Centre for Dentistry Amsterdam (ACTA), Louwesweg 1, 1066 EA Amsterdam, The Netherlands. e-mail: HDenissen@actanlAW Volume 14, Number 2, 2001 177 The International Journal of Prosthodontics