Assessment of bone loss in periodontitis from panoramic radiographs

Automating Periodontal bone loss measurement via dental landmark localisation

PURPOSE

Periodontitis is the sixth most prevalent disease worldwide and periodontal bone loss (PBL) detection is crucial for its early recognition and establishment of the correct diagnosis and prognosis. Current radiographic assessment by clinicians exhibits substantial interobserver variation. Computer-assisted radiographic assessment can calculate bone loss objectively and aid in early bone loss detection. Understanding the rate of disease progression can guide the choice of treatment and lead to early initiation of periodontal therapy.

METHODOLOGY

We propose an end-to-end system that includes a deep neural network with hourglass architecture to predict dental landmarks in single, double and triple rooted teeth using periapical radiographs. We then estimate the PBL and disease severity stage using the predicted landmarks. We also introduce a novel adaptation of MixUp data augmentation that improves the landmark localisation.

RESULTS

We evaluate the proposed system using cross-validation on 340 radiographs from 63 patient cases containing 463, 115 and 56 single, double and triple rooted teeth. The landmark localisation achieved Percentage Correct Keypoints (PCK) of 88.9%, 73.9% and 74.4%, respectively, and a combined PCK of 83.3% across all root morphologies, outperforming the next best architecture by 1.7%. When compared to clinicians' visual evaluations of full radiographs, the average PBL error was 10.69%, with a severity stage accuracy of 58%. This simulates current interobserver variation, implying that diverse data could improve accuracy.

CONCLUSIONS

The system showed a promising capability to localise landmarks and estimate periodontal bone loss on periapical radiographs. An agreement was found with other literature that non-CEJ (Cemento-Enamel Junction) landmarks are the hardest to localise. Honing the system's clinical pipeline will allow for its use in intervention applications.

Periodontitis, assessed using periodontal treatment as a surrogate marker, has no association with a first myocardial infarction in a Swedish population

BACKGROUND

Periodontitis is suggested to be associated with a risk of cardiovascular events. Using periodontal treatment recorded in Swedish national registries as a surrogate marker, we aimed to investigate whether periodontitis was associated with a first myocardial infarction.

METHODS

This nationwide case-control study, with data from national registries, involved 51,880 individuals with a first myocardial infarction in 2011 to 2013 (index date) and 246,978 controls matched 5:1 for age, gender, and geographic area. Periodontal treatment in the 3 years preceding the index date was classified as (1) no dental treatment, (2) no periodontal treatment, (3) one or more supragingival curettages, or (4) one or more treatments with scaling/root planing and/or periodontal surgery. Annual frequencies of treatment with scaling/root planing and/or periodontal surgery were also calculated. In all analyses, conditional logistic regression analyses estimated ORs for myocardial infarction with 95% CIs, adjusted for matched variables, income, education, and diabetes.

RESULTS

Although fewer cases than controls received treatment with scaling/root planing and/or periodontal surgery (19.2% versus 19.8%, P < 0.001), annual frequencies for cases were higher. We found no association of scaling/root planing and/or periodontal surgery with a first myocardial infarction (OR = 1.02; 95% CI: 1.00, 1.05). We did observe a non-significant trend, however, between risk of a first myocardial infarction and a high frequency of scaling/root planing and/or periodontal surgery (OR 1.14; 95% CI: 1.00, 1.29).

CONCLUSION

In the contemporary Swedish nationwide setting, no association between a first myocardial infarction and periodontitis, assessed as periodontal treatment, was found.

Association between Carotid Artery Calcification and Periodontal Disease Progression in Japanese Men and Women: A Cross-Sectional Study

OBJECTIVE

To evaluate the association between alveolar bone loss (ABL) detected on panoramic radiographs and carotid artery calcification (CAC) detected on computed tomography (CT).

METHODS

The study subjects included 295 patients (mean age ± SD: 64.6 ± 11.8 years) who visited the Matsumoto Dental University Hospital. The rate of ABL and the number of present teeth were measured on panoramic radiographs. Univariate analyses with t-tests and chi-squared tests were performed to evaluate the differences in age, gender, history of diseases, number of present teeth, and the ABL between subjects, with and without CAC. Moreover, multivariate logistic regression analysis, with forward selection and receiver operating characteristic curve (ROC) analysis, was performed.

RESULTS

The number of subjects without and with CAC was 174 and 121, respectively. Univariate analyses revealed that CAC was significantly associated with age, hypertension, osteoporosis, number of present teeth, and ABL. Multivariate logistic regression analysis adjusted for covariates revealed that the presence of CAC was significantly associated with ABL (OR = 1.233, 95% CI = 1.167-1.303). In the ROC analysis for predicting the presence of CAC, the the area under the ROC curve was the highest at 0.932 (95% CI = 0.904-0.960) for ABL, which was significant.

CONCLUSIONS

Our results suggest that the measurement of ABL on panoramic radiographs may be an effective approach to identifying patients with an increased risk of CAC.

Severe Periodontitis Is Associated with Myocardial Infarction in Females

The aim of the present study was to test the hypothesis that there is a sex difference in the association between periodontitis (PD) and a first myocardial infarction (MI). The analysis in the case-control study was based on 785 patients (147 females and 638 males) with a first MI and 792 matched controls (147 females and 645 males), screened for cardiovascular risk factors and subjected to a panoramic dental X-ray. Periodontal status was defined by alveolar bone loss and diagnosed as no PD (≥80% remaining alveolar bone), mild to moderate PD (66% to 79%), or severe PD (<66%). Logistic regression was used when analyzing PD as a risk factor for MI, adjusting for age, smoking, diabetes, education, and marital status. The mean age was 64 ± 7 y for females and 62 ± 8 y for males. Severe PD was more common in female patients than female controls (14 vs. 4%, P = 0.005), with an increased risk for severe PD among female patients with a first MI (odds ratio [OR] = 3.92, 95% confidence interval [CI] =1.53 to 10.00, P = 0.005), which remained (OR = 3.72, 95% CI = 1.24 to 11.16, P = 0.005) after adjustments. Male patients had more severe PD (7% vs. 4%; P = 0.005) than male controls and an increased risk for severe PD (OR = 1.88, 95% CI = 1.14 to 3.11, P = 0.005), but this association did not remain following adjustment (OR = 1.67, 95% CI = 0.97 to 2.84, NS). Severe PD was associated with MI in both females and males. After adjustments for relevant confounders, this association did, however, remain only in females. These data underline the importance of considering poor dental health when evaluating cardiovascular risk, especially in females.

Periodontitis Increases the Risk of a First Myocardial Infarction: A Report From the PAROKRANK Study

BACKGROUND

The relationship between periodontitis (PD) and cardiovascular disease is debated. PD is common in patients with cardiovascular disease. It has been postulated that PD could be causally related to the risk for cardiovascular disease, a hypothesis tested in the Periodontitis and Its Relation to Coronary Artery Disease (PAROKRANK) study.

METHODS AND RESULTS

Eight hundred five patients (<75 years of age) with a first myocardial infarction (MI) and 805 age- (mean 62±8), sex- (male 81%), and area-matched controls without MI underwent standardized dental examination including panoramic x-ray. The periodontal status was defined as healthy (≥80% remaining bone) or as mild-moderate (from 79% to 66%) or severe PD (<66%). Great efforts were made to collect information on possibly related confounders (≈100 variables). Statistical comparisons included the Student pairwise t test and the McNemar test in 2×2 contingency tables. Contingency tables exceeding 2×2 with ranked alternatives were tested by Wilcoxon signed rank test. Odds ratios (95% confidence intervals) were calculated by conditional logistic regression. PD was more common (43%) in patients than in controls (33%; P<0.001). There was an increased risk for MI among those with PD (odds ratio, 1.49; 95% confidence interval, 1.21-1.83), which remained significant (odds ratio, 1.28; 95% confidence interval, 1.03-1.60) after adjusting for variables that differed between patients and controls (smoking habits, diabetes mellitus, years of education, and marital status).

CONCLUSIONS

In this large case-control study of PD, verified by radiographic bone loss and with a careful consideration of potential confounders, the risk of a first MI was significantly increased in patients with PD even after adjustment for confounding factors. These findings strengthen the possibility of an independent relationship between PD and MI.

Measuring mandibular asymmetry in Class I normal subjects using 3D novel coordinate system

Introduction:

Orthodontic treatment plays a major role in cosmetic dentistry. A harmonious facial balance is normally the end point in comprehensive orthodontic outcomes. In order to achieve this goal, correct diagnosis of asymmetry should be done starting from the outer facial morphology forms and progressively moving to the dental occlusion. The prime importance of measuring mandibular asymmetry is its tremendous effect on the occlusion.

Objective:

The aim of this study was to measure mandibular asymmetry in a cohort Class I molar relationship comparing right and left sides using new three-dimensions (3D) imaging technique with the aid of 3D software (in vivo 5.2.3 [San Jose, CA]).

Materials and Methods:

35 DICOM files were initially collected retrospectively and seven were excluded due to (1) condylar resorption, (2) history of trauma and (3) unclear DICOM file. A new coordinate system was set for the mid-sagittal plane (MSP), Frankfort horizontal plane and frontal plane (FP). Each cone beam computed tomography (CBCT) was appraised using 16 evaluation criteria bilaterally. Five mandibular landmarks were selected: Condylion_R, Gonion_R, Menton, Gonion_L and Condylion_L. Using these points, the mandible was further divided into four parts: (1) Ramus length right side, body of the mandible right side, body of the Ramus left side and Ramus length left side. The angles between each line and the three different planes were acquired in order to compare each line from a 3D aspect. Mean and standard deviation were calculated for the 28 CBCTs.

Results:

Significant bilateral differences were reported in the angle between the ramus length and MSP and the ramus length and the FP (P < 0.05). Significant lateroanterior shift of the mandibular ramus on the left side in comparison with the right side.

Conclusion:

Viewing an object using three different angles between the four parts of the mandible and each plane is a valid method to replicate the actual object.

Periodontal disease: a new factor associated with the presence of multiple complex coronary lesions

BACKGROUND AND AIM

Periodontal disease, including bone loss, is thought to be involved in coronary artery disease. Multiple complex coronary lesions relate to multifocal destabilization of coronary plaques. We investigated whether bone loss could be associated with the presence of multiple complex coronary lesions.

METHODS

This cross-sectional study included 150 patients with recent myocardial infarction (<1 month). Multiple complex coronary lesions were determined at coronary angiography. A panoramic dental X-ray including bone loss >50% was performed. Patients with no or simple complex lesions were compared to patients with multiple complex lesions.

RESULTS

Over 20% of patients had multiple complex coronary lesions. Patients with multiple complex lesion were less likely to be women and more likely to have multivessel disease or elevated C-reactive protein (CRP) than patients with no or single complex lesion. Bone loss >50% tended to be more frequent in patients with multiple complex lesions (p = 0.063). In multivariate analysis, multivessel disease, gender and CRP were associated with multiple complex lesion. Bone loss >50% increased the risk of multiple complex lesion.

CONCLUSION

Bone loss was associated with complex multiple coronary lesions, beyond systemic inflammation. These findings may bear important clinical implications for the prevention and treatment of coronary artery disease.

External root resorption after orthodontic treatment: a study of contributing factors

Purpose

The purpose of this study was to examine the patient- and treatment-related etiologic factors of external root resorption.

Materials and Methods

This study consisted of 163 patients who had completed orthodontic treatments and taken the pre- and post-treatment panoramic and lateral cephalometric radiographs. The length of tooth was measured from the tooth apex to the incisal edge or cusp tip on the panoramic radiograph. Overbite and overjet were measured from the pre- and post-treatment lateral cephalometric radiographs. The root resorption of each tooth and the factors of malocclusion were analyzed with an analysis of variance. A paired t test was performed to compare the mean amount of root resorption between male and female, between extraction and non-extraction cases, and between surgery and non-surgery groups. Correlation coefficients were measured to assess the relationship between the amount of root resorption and the age in which the orthodontic treatment started, the degree of changes in overbite and overjet, and the duration of treatment.

Results

Maxillary central incisor was the most resorbed tooth, followed by the maxillary lateral incisor, the mandibular central incisor, and the mandibular lateral incisor. The history of tooth extraction was significantly associated with the root resorption. The duration of orthodontic treatment was positively correlated with the amount of root resorption.

Conclusion

These findings show that orthodontic treatment should be carefully performed in patients who need the treatment for a long period and with a pre-treatment extraction of teeth.

Initial periodontal screening and radiographic findings--a comparison of two methods to evaluate the periodontal situation

BACKGROUND

The periodontal screening index (PSI) is an element of the initial dental examination. The PSI provides information on the periodontal situation and allows a first estimation of the treatment required. The dental panoramic tomography (DPT) indicates the proximal bone loss, thus also allowing conclusions on the periodontal situation. In this study, the results of both methods in determining the periodontal situation are compared.

METHODS

The clinical examination covered DMF-T, QHI, and PSI scores at four proximal sites per tooth; the examining dentist was unaware of the radiographic finding. Based on the PSI scores, the findings were diagnosed as follows: score 0 - 2 "no periodontitis", score 3 and 4 "periodontitis". Independent of the locality and time of the clinical evaluation, two dentists examined the DPTs of the subjects. The results were classified as follows: no bone loss = "no periodontitis", and bone loss = "periodontitis".

RESULTS

112 male subjects (age 18 to 58, Ø 37.7 ± 8 years) were examined. Regarding the PSI, 17 subjects were diagnosed "no periodontitis" and 95 subjects "periodontitis". According to the evaluation of the DPTs, 70 subjects were diagnosed "no periodontitis" and 42 "periodontitis". A comparison of both methods revealed that the diagnosis "no periodontitis" corresponded in 17 cases and "periodontitis" in 42 cases (53%). In 47% (53 cases) the results were not congruent. The difference between both methods was statistically significant (p < 0.001; kappa = 0.194).

CONCLUSION

The present study shows that the initial assessment of the periodontal situation significantly depends on the method of evaluation.

Are panoramic images reliable in planning sinus augmentation procedures?

OBJECTIVE

The inherent deformation and two-dimensional nature of panoramic radiographs jeopardise their interpretation and quantitative measurements. This study aims to estimate the degree of underestimation of available mesio-distal bone in the premolar area (comparing panoramic radiographs with multi-slice/cone-beam computer tomography [CT]) to determine the prevalence, width, length and position of the bony canal [artery] in the lateral sinus wall and to explore the prevalence, width and length of another (newly detected) bony canal at the palatal aspect of the upper canine.

MATERIAL AND METHODS

The distance between the distal side of the canine/first premolar and the mesial side of the first molar or the anterior wall of the maxillary sinus was measured on panoramic radiographs and corresponding multi-slice/cone-beam CT images (65 patients). Measurements were made at apical, mid-radicular and crestal regions, parallel to the occlusal plane. The presence and dimensions of the two above-mentioned intra-osseous canals were verified on multi-slice CT scans (144 patients) using reformatted cross-sectional images and/or axial slices.

RESULTS

For all 65 patients, panoramic radiographs underscored the mesio-distal distance of available bone in the upper premolar region (mean 2.9 mm, range 0.1-7.5 mm). An intra-osseous canal in the lateral maxillary sinus wall was clearly visible in 49.5% of the cases (mean diameter 1.4 mm). In the canine region, a bony canal was obvious in 32.9% of the cases, with a mean diameter of 1.23 mm. For both canals, there was no correlation between diameter and patient's age.

CONCLUSIONS

Based on the present data, cone-beam CT imaging can be recommended for visualising anatomical structures during planning of sinus augmentation procedures.

Investigation of periodontal destruction patterns in smokers and non-smokers

BACKGROUND

Previous work has suggested that tobacco smoking has a local as well as a systemic effect on the severity of periodontal disease.

OBJECTIVE

To test the hypothesis that smokers have more disease in the upper anterior region.

METHODS

A retrospective stratified random sample of 49 non-smokers and 39 heavy smokers (>or=20 cigarettes/day) was obtained from a total of 3678 referred patients with adult periodontitis. Probing depth data were collected from clinical records and radiographic measurements were carried out on existing dental panoramic tomographs to assess the inter-proximal bone levels.

RESULTS

The proportion of sites with "bone loss" 4.5 mm or greater was higher in smokers, the greatest difference being observed in upper anterior sites (smokers: 73.3+/-25.5%, non-smokers: 48.3+/-31.2%, p<0.001). A difference was also observed when the number of palatal sites probing 4 mm or greater in the upper anterior region was expressed as a proportion of all such sites in the mouth (smokers: 12.3+/-6.8%, non-smokers: 9.8+/-8.8%; p=0.050).

CONCLUSION

The overall pattern of tissue destruction was consistent with a systemic effect of smoking. The suggestion of a marginal local effect of the smoking habit in maxillary anterior palatal sites requires further investigation.

The prosthodontic concept of crown-to-root ratio: A review of the literature

Crown-to-root ratio is intended to serve as an aid in predicting the prognosis of teeth. However, controversy persists as to its impact on diagnosis and treatment planning. This article critically reviews the available literature on the crown-to-root ratio assessment and criteria for evaluation of abutment use of periodontally compromised teeth. A Medline search was completed for the time period from 1966 to 2003, along with a manual search, to locate relevant peer-reviewed articles and textbooks published in English. Key words used were "crown-to-root ratio," "periodontal compromised dentition," "mobility," and "biomechanics." There was a dearth of evidence-based research on the topic. Although the use of the crown-to-root ratio in addition to other clinical indices may offer the best clinical predictors, no definitive recommendations could be ascertained.

The usefulness of radiographs in diagnosis and management of periodontal diseases: a review

OBJECTIVES

To review the periodontally significant diagnostic information obtainable from radiographs and the stages during periodontal therapy when the information may influence patient management and treatment outcomes.

DATA

Confined to studies involving conventional radiography, as this remains the commonest imaging method in clinical dental practice and primary dental care setting.

SOURCES

Literature was reviewed using Medline and manual tracing of references cited in key papers not otherwise elicited.

STUDY SELECTION

Studies were selected in order to (i) define the role of radiographs in periodontal diagnosis and management at the initial, corrective and supportive (maintenance) phases of periodontal therapy and (ii) critically review the evidence for the value added by radiographs.

CONCLUSIONS

Radiographs provide diagnostic information on alveolar bone levels, plaque retention factors, caries, furcation defects, subgingival calculus and additional pathology. Features visualised are dependent on the radiographic view. A relationship exists between probing attachment loss and radiographic bone height, with a range in level of correlation; clinical attachment may correspond more closely to surgical measurements of bone height. Radiographs can be used in planning initial, corrective and supportive phases of therapy, though some decisions may be made on clinical assessments alone. Evidence in the literature on benefit gained from radiographs taken for periodontal patients is sparse; the extent to which they influence the treatment provided and treatment outcomes is poorly addressed. Further research is indicated to define the role of radiographs when managing the periodontal patient to maximise the potential gain for the patient.

Assessment of alveolar bone levels from intraoral radiographs in subjects between ages 15 and 94 years seeking dental care

Studies have shown that <20% of the US population has periodontal disease. Studies of radiographs have shown that alveolar bone loss increases with age. Bone loss assessed from intraoral radiographs describing 10,282 teeth from 416 subjects seeking dental care during a 3 month period at the University of Washington were studied. The mean age of the subjects was 47.2 years (SD+/-15.2). The youngest subjects (15-24) had on average 29.6 teeth (SD+/-2.2) and the oldest subjects (75-94) 19.3 teeth (SD+/-6.6). This difference was statistically significant (F=16.57, p<0.001). No association was found between alveolar bone loss (CEJ-ABC), and TMD symptoms. Smoking was significantly associated with both general bone loss (CEJ-ABC) (chi(2)=114.9, p<0.0001), and vertical bone defects (angular) (chi(2)=101.8, p<0.0001). In this study population (15-94 years), alveolar bone loss progressed as defined by the slope (beta=0.29) between age 15-44, but was almost flat from age 50 years (beta=0.04). The data suggested an overall rate of alveolar bone loss of 0.02 mm per year. Stepwise multiple regression analysis showed that smoking was the primary factor in bone loss (t= 7.7, p<0.0001), followed by age (t=7.0, p<0.001) and gender (t=3.0, p<0.01). TMD symptoms could not explain the presence and severity of horizontal or vertical defects. If the CEJ-ABC distance above the mean plus 2x the SD was used as the cutoff value to define abnormal bone levels, 10.9% of the younger (15-45 years), and 10.7% of the older subjects (50-94) had significant alveolar bone loss. 73.9% of the younger and 100% of the older subjects with such extent of alveolar bone loss were smokers.

Non-insulin dependent diabetes mellitus and alveolar bone loss progression over 2 years

This study tested the hypothesis that persons with non-insulin dependent diabetes mellitus (NIDDM) have greater risk of more severe alveolar bone loss progression over a 2-year period than those without NIDDM. Data from the longitudinal study of the oral health of residents of the Gila River Indian Community were analyzed for 362 subjects, aged 15 to 57, 338 of whom had less than 25% radiographic bone loss at baseline, and who did not develop NIDDM nor lose any teeth during the 2-year study period. The other 24 subjects had NIDDM at baseline, but met the other selection criteria. Bone scores (scale 0-4) from panoramic radiographs corresponded to bone loss of 0%, 1%-24%, 25%-49%, 50%-74%, or 75% and greater. Change in bone score category was computed as the change in worst bone score (WBS) reading after 2 years. Age, calculus, NIDDM status, time to follow-up examination, and baseline WBS were explanatory variables in regression models for ordinal categorical response variables. NIDDM was positively associated with the probability of a change in bone score when the covariates were controlled. The cumulative odds ratio for NIDDM at each threshold of the ordered response was 4.23 (95% C.I. = 1.80, 9.92). In addition to being associated with the incidence of alveolar bone loss (as demonstrated in previous studies), these results suggest an NIDDM-associated increased rate of alveolar bone loss progression.

Radiographic assessment of peri-implant vertical bone loss: DICRG Interim Report No. 9

Vertical bone loss is being assessed radiographically as part of the Dental Implant Clinical Research Group studies through direct measurements on study radiographs taken longitudinally at surgery and recall appointments. Preliminary results and trends for the period between implant placement and 6 months after implant uncovering show more bone loss in implants that are 1) not coated with hydroxyapatite; 2) placed in the maxilla; 3) placed in anterior regions of the jaws; 4) in completely edentulous cases; and 5) placed in bone scored as having lower quality. Confounding relationships between predictor variables will require controlled statistical analyses when data collection is completed.

Selection of the most accurate method of conventional radiography for the assessment of periodontal osseous destruction

The purpose of the present study was to compare the radiographic measurements of periodontal osseous destruction with the surgical measurements, which represent the true value of osseous destruction, and to select the most successful method of conventional radiography in detecting and accurately assessing periodontal osseous destruction. A total of 5072 proximal surfaces in 2536 teeth of 100 patients with periodontitis were evaluated surgically during periodontal flap surgery and radiographically by using periapical and panoramic radiography. Comparative evaluation of the measurements obtained by these 3 different methods of osseous destruction assessment revealed the following. (1) The radiographic detection ability of small osseous destruction (1-4 mm) was very low for both methods of assessment and became even lower for the initial osseous destruction (1 or 2 mm). (2) Periapical radiography was more successful than panoramic in the detection of osseous destruction, especially of the small destruction (4.7x). (3) Panoramic radiography underestimated the osseous destruction, whereas periapical radiography was relatively accurate in the osseous destruction assessment. (4) Periapical radiography was more accurate in the osseous destruction assessment than panoramic, regardless of the location of the dental surfaces (jaw, tooth group, mesial or distal) and the degree of osseous destruction. (5) The deviation of the radiographic measurements of osseous destruction from the surgical measurements, as well as the difference between the two radiographic methods, depended on the jaw location, the tooth group and the degree of osseous destruction. (6) The radiographic assessment of osseous destruction underestimated the osseous destruction in initial periodontitis, it was relatively accurate in moderate periodontitis, but overestimated it in severe periodontitis. The radiographic measurements of osseous destruction deviated least from the surgical measurements in the group of moderate periodontitis and most in that of severe osseous destruction. (7) The 2 radiographic methods agreed most in the assessment of osseous destruction in the severe periodontitis group and least in the initial periodontitis group. (8) The indirect Schei method was less successful in detecting the small osseous destruction and less accurate in assessing the osseous destruction than the direct millimetric method of radiographic evaluation. (9) The osseous destruction as assessed from periapical radiographs by the Schei method was not significantly different from that assessed by the radiopaque Fixot-Everett grid. The results of the present study suggest that periapical radiography is more successful in detecting periodontal osseous destruction and more accurate in assessing it than panoramic radiography.

Quantitative assessment of vertical heights of maxillary and mandibular bones in panoramic radiographs of elderly dentate and edentulous subjects

The clinical applicability of vertical measurements of the mandible and maxilla in panoramic radiographs was studied by assessing the variety of vertical heights among 91 elderly dentate subjects. Measurements in each jaw and calculations of a maxillary ratio were made at five sites. Variations in measurements of the dentate subjects were small: 9-11% for vertical measurements in the mandible, 6-11% for vertical measurements in the maxilla, and 8-10% for the maxillary ratios. These findings suggest that it is possible quantitatively to assess heights of the mandibular and maxillary bones in panoramic radiographs. Reductions in the edentulous jaws were assessed by comparing the heights of jaws of elderly dentate subjects with those measured in 177 elderly edentulous subjects. Significant differences in heights of the mandibular body and maxilla were found between the dentate and the edentulous (P < 0.001). Edentulous women had greater values for percentage reduction in the mandibles than did the men (P < 0.01; P < 0.001 in various locations).

The relationship of bone loss observed on panoramic radiographs with clinical periodontal screening

The aim of this study was to determine the relationship between bone levels observed on dental panoramic tomographs (DPT) and the WHO/FDI recommended periodontal screening technique: the community periodontal index of treatment needs (CPITN). Computer enhancement and digital analysis were used to improve accuracy and reliability. A total of 199 posterior sextants on DPT radiographs from 50 patients (29 female and 21 male) with a mean age of 42 were examined. A statistically significant relationship was found between CPITN and radiographic measurement from the cemento-enamel junction to the alveolar crestal bone margin (A). The relationship between A and CPITN was found to fit the following equation: square root of A = beta 1 + F, where, F is constant and beta 1 is the coefficient corresponding to the i the codes of CPITN. It was concluded that there was a close correlation between the CPITN screening codes and bone loss as measured on the DPT radiograph.

The use of panoramic radiology in dental practice

OBJECTIVES

Approximately 1.5 million panoramic radiographs are taken annually in the general dental service in England and Wales. The aim of this review was to assess the clinical role of panoramic radiology in the diagnosis of diseases associated with the teeth and to consider its value in routine screening of patients.

METHOD

This was carried out by critical review of the literature.

RESULTS

In addition to common problems with radiographic technique and processing, there are limitations in image quality inherent to panoramic radiology. These factors contribute to a reduced diagnostic accuracy for caries diagnosis, demonstration of periodontal bone support and periapical pathology when compared with intraoral radiography. Routine screening is unproductive for large proportions of dentate and edentulous populations, while in those cases where pathology is detected the diagnostic accuracy can be questioned. Furthermore, the "detection' of asymptomatic anomalies may have no effect on patient management. Attempts to develop and test panoramic radiographic selection criteria are reviewed.

CONCLUSIONS

New, high-yield selection criteria for panoramic radiography are proposed as a means of reducing unnecessary examinations, limiting radiation doses and reducing financial costs to patients and health service providers. However, research is indicated to develop further and to test such selection criteria.

Apical root resorption in orthodontically treated subjects: analysis of edgewise and light wire mechanics

Of the several modes of tooth movement, pressure from intrusive forces seems the most likely to cause external apical root resorption (EARR). This has been demonstrated for incisors in human beings and molars in laboratory animals. The present study examined full-banded adolescent patients and scored the degrees of in-treatment root resorption throughout the dentition. Just Class I cases with four first premolar extractions were used. Equal samples of conventional Begg and Tweed treated cases were examined with 1:1 sex ratios (total n = 83). No difference between the Begg and Tweed techniques and no sex difference was found in any of the 30 univariate tests, even though power analysis indicated a strong likelihood of finding a difference if one existed. By using multiple linear regression, significant decreases in length (EARR) were found for those roots systematically intruded in this Class I malocclusion, notably the mesial root of the maxillary first molar and the distal root of the mandibular first molar. Even though some of the present cases had been in "active" treatment up to 6 years, we found no significant association between duration of treatment and degree or amount of EARR.

Clinical comparison of two panoramic modalities and posterior bite-wing radiography in the detection of proximal dental caries

A clinical study was designed to examine whether the Philips OrthOralix SD (Gendex Dental Systems, Monza, Italy) orthogonal panoramic projection could improve diagnostic accuracy over standard projections in the detection of proximal surface caries. Thirty-five sets of radiographs that demonstrated optimal image characteristics were selected. Using a five-point scale, 18 viewers evaluated whether specified lesions were present or absent. Viewer data was then compared with a consensus radiographic assessment of the state of the proximal areas. Receiver operating characteristic curves were generated with the use of a maximum-likelihood method of fit. The area under the receiver operating characteristic curve was used as the index of diagnostic accuracy. The mean receiver operating characteristic areas for orthogonal and standard projection panoramic and bite-wing radiography to detect the presence of proximal dental caries were 0.68 +/- 0.03, 0.69 +/- 0.03, and 0.79 +/- 0.03 respectively. Critical ratio analysis was used to compare the means for all possible pairings of imaging modalities. In overall performance, conventional bite-wing radiographs gave a significantly greater diagnostic yield for proximal caries than the Philips OrthOralix SD orthogonal or standard panoramic modalities (p > 0.05). The orthogonal projection did not improve diagnostic accuracy in the detection of proximal carious lesions compared with the standard projection.

A twin study of genetic variation in proportional radiographic alveolar bone height

The purpose of this study was to estimate the genetic variance for alveolar bone height by means of the classic twin method and the study of monozygous twins reared apart. Panoramic radiographs were obtained from 120 pairs of adult twins (mean age = 40.4 years, S.D. = 10.4 years), for comparison of 62 pairs of monozygous twins reared together (MZT), 25 pairs of like-sexed dizygous twins reared together (DZT), and 33 pairs of monozygous twins reared apart (MZA). Mesial and distal bone heights were determined as a proportion of tooth length. A full-mouth bone score was computed for each twin by averaging these proportions from all measurable teeth. Between-pair (B) and within-pair (W) variances were computed for each twin group. The population variances (B + W) of the MZT and DZT twin groups were similar, which validated a basic assumption of the twin model. Intraclass correlations and heritability estimates were also computed for the reared-together and reared-apart twin groups. Boot-strap sampling was used to provide estimates and confidence limits for these values. The intraclass correlations for the twin groups were: MZT = 0.70, DZT = 0.52, and MZA = 0.55. The results of this study suggest that there is significant genetic variance in the population for proportional alveolar bone height.

Agreement between panoramic and intra-oral radiography in the assessment of marginal bone height

Panoramic and intra-oral radiographs from 400 consecutive patients were evaluated for the assessment of the marginal bone height. Two hundred panoramic radiographs were exposed with the rotational technique and 200 with the intra-oral X-ray tube technique. Measurements of the approximal marginal bone level were independently performed by two observers. Complete agreement between panoramic and intra-oral radiographs was, on average, obtained in 55% and 49% of the sites, respectively. When the criterion for agreement was widened to include recordings with a difference of +/- 1 mm, the agreement was on average 87% irrespective of the techniques compared. The agreement varied with tooth type and severity of the marginal bone loss. Angular bony defects and furcation involvements were recorded separately. For angular bony defects there was a variation in agreement from 33% to 46% for the rotational technique and from 35% to 51% for the intra-oral X-ray tube technique depending on localization. Furcation involvements of the molars were equally recorded in 60% and 59%, respectively, but in only 12% and 28% for the upper premolars. Interobserver agreement was 58% for the intra-oral radiographs, 60% and 59% for the two panoramic techniques. Mean intra-observer agreement was 68%, 66% and 68%. It is concluded that panoramic radiography can often be used for the assessment of marginal bone loss alone, supplemented when necessary by intra-oral radiographs.