Extraoral control of geometry for digital subtraction radiography

Exposure time reduction of secondary radiographs used in digital subtraction radiography in detecting intrabony change

Objectives

Digital subtraction radiography (DSR) is a suitable technique for detecting incipient bone changes. However, in DSR, one or more follow-up radiographs must be taken. The aim of this study was to assess the possibility of reducing the exposure time for the radiographs that follow the initial one.

Methods

Maxillary premolar and molar radiographic images of a dry skull were taken with a digital radiography system. The initial radiographs, without bone chips, were taken at 0.32 and 0.16 s. Then, five bone chips (weight range 7–15 mg) were placed on the maxillary molar buccal side of the dry skull. Secondary radiographs were taken at 0.32-, 0.16-, 0.08-, 0.04-, and 0.02-s exposure times. For each bone chip, radiographs were taken three times. The secondary and initial images were subtracted to yield subtraction images. Four observers were asked to evaluate bone change visibility in the subtraction images. The Friedman test was used for statistical analysis.

Results

Significant differences were seen at each of the settings for the 0.32-s group (p = 1.24e−030) and 0.16-s group (p = 7.52e−009). By comparing the different groups, observer evaluations indicated that visibility changed when the secondary radiograph was taken at 1/8 of the exposure time of the initial radiograph. In both groups, the visibility of the 0.02-s subtraction image was significantly lower than that of the other subtraction images.

Conclusion

In DSR, the exposure time of the secondary radiograph can be reduced to 1/4 of the exposure time of the initial radiograph.

Serum bone biomarkers and oral/systemic bone loss in humans

We recently reported that subantimicrobial-dose doxycycline (SDD) significantly reduced serum bone-resorption biomarkers in subgroups of post-menopausal women. We hypothesize that changes in serum bone biomarkers are associated not only with systemic bone mineral density (BMD) changes, but also with alveolar bone changes over time. One hundred twenty-eight eligible post-menopausal women with periodontitis and systemic osteopenia were randomly assigned to receive SDD or placebo tablets twice daily for two years, adjunctive to periodontal maintenance. Sera were analyzed for bone biomarkers. As expected, two-year changes in a serum bone biomarker were significantly associated with systemic BMD loss at the lumbar spine (osteocalcin, bone-turnover biomarker, p = 0.0002) and femoral neck (osteocalcin p = 0.0025). Two-year changes in serum osteocalcin and serum pyridinoline-crosslink fragment of type I collagen (ICTP; bone-resorption biomarker) were also significantly associated with alveolar bone density loss (p < 0.0001) and alveolar bone height loss (p = 0.0008), respectively. Thus, we have shown that serum bone biomarkers are associated with not only systemic BMD loss, but with alveolar bone loss as well.

CLINICAL TRIAL REGISTRATION INFORMATION

Protocol registered at ClinicalTrials.gov, NCT00066027.

Inflammatory mediator release following bone grafting in humans: a pilot study

AIM

The aim of this pilot study was to track markers of periodontal inflammation and bone resorption associated with decalcified freeze-dried bone allografts.

MATERIAL AND METHODS

Eleven subjects completed standardized treatment of intrabony defects > or =3 mm with allografts. Gingival crevicular fluid was collected from the defect site and an adjacent interproximal site within the surgical field at baseline, 2, 4, and 8 weeks post-operatively, and analysed for biochemical markers of inflammation/bone resorption. Probing depth, recession, bleeding on probing, plaque, and 6-month radiographic bone height change were measured.

RESULTS

Both prostaglandin E(2) (p=0.007) and bone-specific type 1 collagen (p=0.01) increased in crevicular fluid after 2 weeks in the bone graft sites. Matrix metalloproteinase-9 levels remained constant over time. There were positive correlations between prostaglandin levels during the first 8 weeks and bone height change over 6 months.

CONCLUSIONS

Periodontal bone grafts stimulate an inflammatory response during the first 2 weeks post-operatively, and the potential negative effects of inhibiting prostaglandins post-operatively should be investigated further.

Subantimicrobial dose doxycycline effects on alveolar bone loss in post-menopausal women

AIM

Determine the efficacy of 2-year continuous subantimicrobial dose doxycycline (SDD; 20 mg bid) on alveolar bone in post-menopausal osteopenic, oestrogen-deficient women undergoing periodontal maintenance in a 2-year double-blind, placebo-controlled, randomized clinical trial.

MATERIAL AND METHODS

One-hundred and twenty-eight subjects randomized to SDD or placebo (n=64 each). Posterior vertical bite wings taken at baseline, 1 and 2 years for alveolar bone density (ABD), using radiographic absorptiometry (RA) and computer-assisted densitometric image analysis (CADIA), and alveolar bone height (ABH). Statistical analyses utilized generalized estimating equations; primary analyses were intent to treat (ITT). Results are presented as SDD versus placebo.

RESULTS

Under ITT, there was no statistically significant effect of SDD on ABD loss (RA: p=0.8; CADIA: p=0.2) or ABH loss (p=0.2). Most sites (81-95%) were inactive. For subgroup analyses, mean CADIA was higher with SDD for non-smokers (p=0.05) and baseline probing depths > or =5 mm (p=0.003). SDD was associated with 29% lower odds of more progressive ABH loss in women >5 years post-menopausal (p=0.05) and 36% lower among protocol-adherent subjects (p=0.03).

CONCLUSIONS

In post-menopausal osteopenic women with periodontitis, SDD did not differ overall from placebo. Based on exploratory subgroup analyses, additional research is needed to determine the usefulness of SDD in non-smokers, subjects >5 years post-menopausal and in deeper pockets. Protocol registered at (ClinicalTrials.gov). Identifier: NCT00066027.

The monitoring of deep caries lesions after incomplete dentine caries removal: results after 14–18 months

This paper aims to assess radiographic changes after incomplete carious dentine removal and tooth sealing. Thirty-two teeth with deep caries lesions were studied. The treatment consisted of incomplete excavation, application of a Ca(OH)2 layer, sealing temporarily for a 6- to 7-month period and then restoration. Standardised bitewing radiographs were taken immediately after the temporary sealing and at 6- to 7- and 14- to 18-month intervals. The digitised images were analysed blind by image subtraction. The quantitative analyses subtractions were performed in the radiolucent zone (RZ) beneath the restoration and in two adjacent control areas (CA). Two cases were lost during the 6- to 7-month period (one pulp necrosis and one pulp exposure during removal of the provisional sealing). No difference (p > 0.05) was observed in the radiographic density of the CA and the RZ in the two experimental periods. The mean and standard deviation (grey tonalities scale) were 129.42+/-5.83 and 127.65+/-4.67 (control areas) and 132.96+/-7.41 and 132.90+/-5.99 (RZ) for the first and second experimental periods, respectively. The radiographic density of the CA differed from the RZ (Tukey test, p < 0.001). Interference in environmental conditions by partial dentine caries removal and tooth sealing arrests lesion progression, suggesting that complete dentine caries removal is not essential to control caries progression.

Digital Subtraction Technique for Evaluation of Peri-Implant Bone Change in Digital Dental Imaging

The purpose of this study was to investigate digital subtraction technique in digital dental imaging for implant performance, used to quantitatively evaluate bone change around dental implants. For longitudinal assessment of peri-implant bone change, we applied subtraction technique to digital peri-apical radiographs using a digital dental imaging system in two cases at the upper canine and premolar regions. In both cases, we found two peaks of bone change at the crestal region; we also quantitatively demonstrated a marked change over the first one-month period and approximately three-month period spanning the fourth month to the end of the sixth month following implantation. Digital peri-apical radiography accommodating the digital subtraction program should be re-acknowledged as a reliable modality for assessing amount of bone change at local implantation sites.

Reliability of Linear Distance Measurement for Dental Implant Length with Standardized Periapical Radiographs

The purpose of this study was to investigate the accuracy of distance measurements of implant length based on periapical radiographs compared with that of other modalities. We carried out an experimental trial to compare precision in distance measurement. Dental implant fixtures were buried in the canine and first molar regions. These were then subjected to periapical (PE) radiography, panoramic (PA) radiography, conventional (CV) and medical computed (CT) tomography. The length of the implant fixture on each film was measured by nine observers and degree of precision was statistically analyzed. The precision of both PE radiographs and CT tomograms was closest at the highest level. Standardized PE radiography, in particular, was superior to CT tomography in the first molar region. This suggests that standardized PE radiographs should be utilized as a reliable modality for longitudinal and linear distance measurement, depending on implant length at local implantation site.

Quantitative analysis of errors in alveolar crest level caused by discrepant projection geometry in digital subtraction radiography: An in vivo study

OBJECTIVE

This study compared the difference between 3 intraoral radiographic techniques on digital subtraction radiography (DSR) in vivo that are commonly used in a clinical setting.

STUDY DESIGN

We evaluated and statistically analyzed the errors in the DSR image in 6 regions with 3 radiographic techniques: paralleling technique with a bite block attached to XCP, paralleling technique using XCP, and bisecting-angle technique.

RESULTS

The amount of error using the bisecting-angle technique was too large for DSR, compared to that of the paralleling technique with a bite block attached to XCP. In the mandibular anterior region, the paralleling technique using XCP was not different from paralleling technique with a bite block attached to XCP. The lowest degree of error was present in the anterior region whereas the highest was present in the molar region.

CONCLUSION

Bisecting-angle technique should be avoided, and paralleling technique using XCP can be used in the mandibular anterior region for DSR.

An in-vitro and in-vivo methodology study of alveolar bone measurement using extra-oral radiographic alignment apparatus, Image Pro-Plus® software and a subtraction programme

OBJECTIVES

(a) To validate a method for acquiring reproducible radiographic images and repeatable measurements of digital images. (b) To investigate the clinical and radiographic changes following periodontal surgery and in a periodontally healthy control group.

METHODS

In-vitro study. Sixteen dried human skulls had replicate intra-oral radiographs taken using an extra-oral alignment apparatus under simulated clinical conditions, and measurements were made on the images using Image Pro-Plus analysis software. In-vivo study. Seven subjects, aged 38-63 years with chronic periodontitis, were treated using replaced flap surgery. Nine patients with healthy periodontal tissues were recruited as a control group. Clinical measurements and radiographs were taken pre-surgery and 6 months afterwards, and at the same interval for untreated healthy controls using the alignment apparatus. Radiographs were analysed using Image Pro-Plus and subtraction radiography.

RESULTS

Radiographs had a high degree of reliability (ICC 0.98-0.99) for the in-vitro study and intra-operator repeatability of measurements was high (ICC 0.65-0.99) for the in-vivo study. Over this interval there were both significant clinical improvements and in bone gain within infra-bony defects on radiographs. Subtracted images showed that out of 17 surgically treated sites, 13 showed evidence of bone gain, one showed no change, two showed bone loss and one could not be interpreted due to poor alignment. Overall there were no significant clinical or radiographic changes in the control group.

CONCLUSIONS

Radiographic images were highly reproducible. Measurements had a high degree of repeatability. The methods used allowed accurate quantitative and qualitative measurement of change in alveolar bone. This technique would allow accurate measurement of any changes in alveolar bone levels in patients with periodontal disease.

Bisphosphonate therapy improves the outcome of conventional periodontal treatment: results of a 12-month, randomized, placebo-controlled study

BACKGROUND

Bone loss in periodontitis results from inflammatory reactions that stimulate osteoclastic bone resorption. Bisphosphonates inhibit bone resorption and increase bone mass. This study evaluated the effect of bisphosphonate therapy as an adjunct to non-surgical periodontal treatment in patients with moderate to severe chronic periodontitis.

METHODS

Patients were randomized (2:1) to one of two bisphosphonate therapies or placebo for 1 year. All patients received non-surgical periodontal treatment (scaling, root planing) and periodontal maintenance therapy every 3 months. Clinical assessments at baseline and 6 and 12 months included clinical attachment level (CAL), probing depth (PD), and bleeding on probing (BOP). Periodontal bone mass was assessed by dental radiographs at baseline and 12 months using fractal analysis and digital subtraction radiography (DSR).

RESULTS

Seventy patients were randomized, 43 to the bisphosphonate group and 27 to the placebo group. Bisphosphonate therapy significantly improved CAL, PD, and BOP relative to the placebo group during the 6- to 12-month period (CAL, P = 0.0002; PD, P = 0.0156; BOP, P = 0.0079). There was no difference in the change in periodontal bone mass between the bisphosphonate and placebo groups as measured by fractal analysis and DSR.

CONCLUSION

These data suggest that bisphosphonate treatment improves the clinical outcome of non-surgical periodontal therapy and may be an appropriate adjunctive treatment to preserve periodontal bone mass.

Use of a simple intraoral instrument to standardize film alignment and improve image reproducibility

OBJECTIVE

A lot of instruments and devices were reported in standardized realignment of intraoral film. However, these instruments either are too cumbersome and time consuming to be used or require extensive fabrication. In this study we described a prototype of a instrument for realignment of intraoral film and evalated its reproducibility.

STUDY DESIGN

A technique that uses this instrument was compared with a validated method serving as control. An adult human dry skull with full dentition was exposed for measuring the angular errors. Two types of angular errors were calculated.

RESULTS

of the analysis of the alignment error caused by projection of the x-ray beam showed the mean horizontal angulation error (+/-SD) was 1.70 +/- 0.75 degrees and the vertical one was 1.32 +/- 0.44 degrees in the new instrument group, and 1.65 +/- 0.70 degrees and 1.40 +/- 0.61 degrees, respectively, in the control group. Bite block seating error was 2.12 +/- 0.55 degrees in the newly developed instrument and 2.01 +/- 0.49 degrees in the instrument with registration material. Statistical analysis showed no significant difference in the 2 instruments (P > .05).

CONCLUSION

The prototype of the new instrument reported by the authors can produce almost identical radiographs in vitro with only slight angular errors. Clinical use of the advanced type of the instrument can be expected to show similar results.

Periodontal maintenance in a specialist periodontal clinic and in general dental practice

OBJECTIVES

To monitor the efficacy of periodontal maintenance whether conducted in a specialist periodontology clinic or in the practice of the referring general dentist.

MATERIALS AND METHODS

Thirty-five subjects with a diagnosis of moderate-severe chronic periodontitis who were referred to the specialist clinic received periodontal non-surgical therapy. Following a 6-month healing phase, subjects were randomly allocated to one of two groups: A (n=18, periodontal maintenance provided within the specialist clinic) or B (n=17, periodontal maintenance provided by the referring general dentist in accordance with written instructions provided by the specialist). All subjects were examined at months 0 (corresponding to 6 months post-completion of non-surgical therapy), 6 and 12. Full-mouth plaque index (PI), % bleeding on probing (%BOP) and probing depth (PD) measurements were recorded. PDs were also recorded at eight test sites which, prior to non-surgical therapy, exhibited PD 5-8 mm, BOP and radiographic alveolar bone loss. Standardized radiographs were exposed at test sites at months 0 and 12, and bone changes assessed using digital subtraction radiography (DSR).

RESULTS

As a result of the non-surgical therapy, statistically significant improvements in all clinical parameters were recorded. In the maintenance period, mean PI increased significantly from months 0 to 12 (p<0.05), but this increase did not differ significantly between groups A and B (p>0.05). No other clinical parameters changed significantly in the maintenance phase of the study. Reductions in %BOP, mouth mean PD and mean test sites PD achieved by the non-surgical therapy were maintained and did not differ significantly whether subjects were allocated to group A or group B (p>0.05). Current smokers had significantly deeper PD than non-smokers and former smokers at all time points (p<0.05), although otherwise, smoking status did not affect the outcomes of the study. DSR analysis identified statistically non-significant, slight, alveolar bone loss in both groups between months 0 and 12.

CONCLUSION

In the short term, periodontal maintenance can be provided in general dental practice with the same expected outcomes compared with maintenance that is provided in a specialist clinic, providing that general dentists are given specific instructions regarding the maintenance regimen. A strong emphasis on effective plaque control is necessary.

An overview of radiographic film holders

OBJECTIVES

To provide an overview of radiographic film holders, from their inception in the early 1900s to present day.

METHODS

A Medline literature search was conducted for dental studies that used keywords that pertain to radiographic film holders. Hand searches of the bibliographies were also conducted. Sixty articles (dating from 1896 to 1998) that describe new or improved film holders are reviewed here.

RESULTS

From the earliest days of dental radiography, dentists attempted to standardize radiographic images and techniques. The focus of researchers in the 1950s to the 1970s was to develop a film holder that would hold the film and allow easy and predictable alignment of the X-ray tube. As research projects became more dependent on dental radiographic measurements, the focus shifted to producing reproducible radiographic images, from which highly repeatable measurements could be made.

CONCLUSION

Existing devices have strengths and weaknesses. Readily available devices are adequate for routine clinical use; however, user-friendly and patient-friendly film-holding devices that result in highly reliable and accurate measurements have yet to be introduced.

Development and evaluation of digital subtraction radiography computer program

OBJECTIVE

We developed a new program for digital subtraction radiography (DSR) having useful functions to get the DSR image more accurately and efficiently. The purpose of this study was to evaluate the accuracy of the DSR image acquired using the new program as compared with the ready-made program.

STUDY DESIGN

Four observers performed the DSR process using our program and the ready-made program for digital intraoral radiographs taken from incisor, premolar, and molar regions. The statistical difference was evaluated between the programs, between the observers, and between the regions.

RESULTS

The DSR image using our program was superior to that with the ready-made program in all the observers and all the radiographed regions. Also, there was the statistical difference among the observers, especially in our program.

CONCLUSION

The DSR image using the new program was very accurate compared with ready-made program, so the program was useful to get an accurate DSR image.

Comparison Between Subtraction Radiography and Conventional Radiographic Interpretation During Long-Term Evaluation of Periodontal Therapy in Class II Furcation Defects

BACKGROUND

Limited information comparing digital subtraction radiographic assessment with conventional radiographic interpretation is available from longitudinal clinical trials. The aim of this study was to evaluate the ability to detect periodontal bone changes during the long-term maintenance of Class II furcation defects by conventional radiographic interpretation compared to interpretation of digital subtraction images.

METHODS

Standardized radiographs of 18 Class II furcation defects in mandibular molars were taken at baseline and at 6, 12, 18, and 24 months after non-resective periodontal surgery. Conventional radiographic and digital subtraction interpretations were performed masked, respectively, by two and three experienced examiners, according to the following categories: bone gain; bone loss; unchanged appearance; and impossible to visualize. Percent concordance and the kappa statistic value (kappa) were computed.

RESULTS

Conventional radiographic and digital subtraction interpretation images resulted in 72 decisions for each examiner. The visual interpretation of digital subtraction images by two examiners revealed the same results. The interpretation of conventional radiographic images showed a low concordance between examiners (kappa < 0.40) at all examinations. The concordance between subtraction radiography and conventional radiographic interpretation was also low for all examiners (kappa < 0.36) at all examinations. Using subtraction radiography as a reference, bone changed and bone unchanged were diagnosed correctly in 47.2% of cases by examiner A, in 43.1% by examiner B, and in 38.9% by examiner C.

CONCLUSION

It can be concluded that conventional radiographic interpretation is a more subjective and inaccurate method of detecting periodontal bone changes in Class II furcation defects in mandibular molars when compared with subtraction radiography.

Digital Radiograph Registration and Subtraction: A Useful Tool for the Evaluation of the Progress of Chronic Apical Periodontitis

The purpose of this study was to evaluate the suitability of a digital radiograph registration and subtraction software for a sensitive and reliable assessment of the progress of chronic apical periodontitis. Ninety cases of teeth with chronic apical periodontitis have been studied. In each case, a preoperative radiograph was taken, root canals were prepared, and a Ca(OH)2 paste was placed in the root canals. Radiographic control and replacement of Ca(OH)2 paste took place at 15-day intervals. The root canals were obturated 1.5 months after the first appointment. Recall radiographs were taken 0.5, 1.5, 3, 6, and 12 months after the obturation. All radiographs were taken for each case under constant conditions by using a direct digital radiography system. In each case, the preoperative, postoperative, and control and recall radiographs were digitally registered and pairwise subtracted. The resulting images were further processed by using contrast enhancement and pseudocoloring methods. Changes to the periapical tissue structure were easily detectable by using the above-mentioned methodology, even during short time intervals.

A Technique for Standardized Evaluation of Soft and Hard Peri-Implant Tissues in Partially Edentulous Patients

BACKGROUND

There is a growing need to evaluate the esthetics of implant-supported crowns and bridges. An important tool for such an evaluation is standardized assessment of the soft and hard peri-implant tissue levels.

METHODS

A simple acrylic device has been developed for reliable and reproducible assessment of soft and hard peri-implant tissues using standardized color slides and standardized dental x-rays. With this device, changes in both the soft and hard tissues around implant-supported crowns can be evaluated as a function of time. The reproducibility of the technique was tested on color slides as well as on dental x-rays in a series of implant-supported crowns and their neighboring teeth.

RESULTS

The reproducibility of this technique was excellent. The measuring errors for repeated measurements of the soft and hard tissues were 0.14 +/- 0.02 mm and 0.13 +/- 0.01 mm, respectively.

CONCLUSIONS

The device is a reliable tool to assess changes in both soft and hard tissues around crowns and implants over time. Likewise, it is suggested that this technique also can be used to objectively assess soft and hard tissue changes around natural teeth with or without prosthetic restorations.

Local biochemical markers of bone turnover: relationship to subsequent density of healing alveolar bone defects

OBJECTIVES

This pilot study was designed to test whether biochemical markers of bone turnover in washes of periosteal or trabecular alveolar bone surfaces could be correlated with increases in bone density of an adjacent healing implant socket.

METHODS

Ten subjects had a canula inserted into the alveolar crest and sterile phosphate-buffered saline was washed over the periosteal and trabecular surfaces and collected. Surgical flaps were reflected, 5 mm diameter bone cores were removed from the bone wash site, and standardized radiographs were taken. The sites were allowed to heal for 12 weeks, and radiographs were repeated. Bone washes of the healing sites were also collected after 2 and 12 weeks. Washes were analysed for bone turnover markers osteocalcin (OC; radioimmunoassay) and C-terminal telopeptide of Type 1 collagen (ICTP; enzyme-linked immunosorbent assay (ELISA)), and blood component albumin (ALB; ELISA). Changes in bone density during healing were determined by radiographic absorptiometry.

RESULTS

OC/ALB and ICTP/ALB ratios were higher for trabecular than periosteal washes at baseline (p<or=0.01). Trabecular OC/ALB and ICTP/ALB were inversely correlated with increasing bone density of the healing bone core socket (r=-0.72, p=0.03; Pearson's correlation coefficient).

CONCLUSIONS

Biochemical markers of bone turnover in bone washes of specific alveolar bone sites may prove helpful in predicting how the bone density will increase around healing dental implants.

Position Paper: Diagnosis of Periodontal Diseases

At the present time, the diagnosis and classification of periodontal diseases are almost entirely based on traditional clinical assessments. Supplemental quantitative and qualitative assessments of the gingival crevicular fluid and subgingival microflora can potentially provide useful information about the patient's periodontal disease. In certain situations, these supplemental risk-assessment tests may be particularly valuable in establishing the endpoint of therapy prior to placing patients on a periodontal maintenance program. Although the clinical utility of none of these tests has been validated, their further development is warranted. A genetic test for susceptibility to periodontitis has become commercially available. How best to use this and future host-based tests in clinical practice remains to be determined. Probing depth and clinical attachment loss measurements obtained with periodontal probes are practical and valid methods for assessing periodontal status. Computer-linked, controlled-force electronic periodontal probes are commercially available and are currently in use by some practitioners. Many of the logistical problems associated with subtraction radiography are being overcome and this powerful diagnostic tool may soon come into widespread use. Future developments in this and other imaging techniques are likely to have a profound effect on our approach to the diagnosis of periodontal diseases.

Efficacy of controlled-release subgingival chlorhexidine to enhance periodontal regeneration

BACKGROUND

Periodontal regeneration success may be limited by placing bone grafts and membranes in infected sites. The objective of this study was to test the hypothesis that adjunctive subgingival administration of chlorhexidine gelatin bioresorbable chips enhances bone gain when used in conjunction with guided tissue regeneration.

METHODS

This was a single center, blinded, 2-arm parallel design study of 44 subjects with one or more sites with probing depth and clinical attachment loss > or = 5 mm following initial therapy and radiographic evidence of bone loss. The patients were randomly assigned to receive either chlorhexidine (CHX) chip or sham chip placement one week prior to regenerative therapy that included graft placement and site coverage with guided tissue membranes. Patients also received CHX or sham chip placement, per their randomization, adjunctively to scaling and root planing or maintenance procedures. Periodontal examinations were completed at baseline (8 weeks prior to surgery); 1 week prior to surgery; and at 3, 6, and 9 months postsurgery. The major outcomes for the study were changes in bone height and bone mass as measured from standardized radiographs used for quantitative digital subtraction radiography over the 11-month study period.

RESULTS

Subjects receiving sham chip placement gained a mean bone height of 1.49 +/- 0.22 mm, while patients receiving the CHX chips gained significantly more bone height (3.54 +/- 0.45 mm; P<0.001). Similarly, subjects receiving CHX chips as an adjunct gained significantly more bone mass (5.57 +/- 0.69 mg; P<0.001) than the standard therapy (2.59 +/- 0.34 mg).

CONCLUSIONS

These pilot results indicate that locally delivered, controlled-release antimicrobial treatment may improve the amount of bone gain during guided tissue regeneration procedures. These data support the evidence that infection control is an important variable in successful regeneration.

Feasibility of an HA2 domain-based periodontitis vaccine

In a rat periodontitis model, preinoculation with the Porphyromonas gingivalis HA2 binding domain for hemoglobin provided protection from disease. Protection was associated with induced anti-HA2 immunoglobulin G (IgG) humoral antibodies. The IgG subclass ratios suggested that relatively lower Th2/Th1-driven responses were directly associated with protection when rHA2 was administered in saline.

Clinical and radiographic evaluation of periodontal intrabony defects treated with guided tissue regeneration. A pilot study

BACKGROUND

The aim of this clinical and radiographic study was to evaluate the effect of guided tissue regeneration using a bioabsorbable barrier in the treatment of intrabony defects in humans.

METHODS

Intrabony osseous defects (2 or 3 walls) around mandibular canines and premolars were treated in 10 systemically healthy patients with ages ranging from 35 to 56 years. Prior to the surgical phase, patients were enrolled in a strict maintenance program including oral hygiene instructions and scaling and root planing (presurgical Pi and GI < 10%). Patients were seen for professional prophylaxis during the duration of the study. Clinical measurements were performed with an electronic probe at baseline and at reentry 8 months following surgical therapy. Measurements included clinical attachment levels (CAL), gingival margin levels (GML), probing depths (PD), bone defect levels (BDL), and alveolar crest level (ACL). A split mouth design was used. Quadrants were randomly assigned for treatment by GTR (experimental) or open flap debridement alone (control). Standardized radiographs were taken at baseline and at reentry. Digital images were analyzed by subtraction to assess changes in area (A) and optical density (OD). Data were evaluated using paired t test.

RESULTS

Statistically significant differences were found in both groups when comparing baseline and post-treatment values for CAL, GML, PD, and BDL (P < 0.0 1). Greater reductions in BDL and gain in A and OD were observed in the GTR group when compared to control (P < 0.01). Both therapies were effective in improving the clinical parameters assessed.

CONCLUSION

Clinical and radiographic findings from this study demonstrated more bone fill in sites treated with GTR.

Histomorphological evaluation of loaded plate-form and root-form implants in Macaca mulatta monkeys

As part of a long-term evaluation of endosteal dental implants in primates, this paper describes the histological response to plate-form and root-form implants. Thirty-six primates received 48 mandibular distal abutment implants. After healing, the implants were restored with fixed partial dentures, which remained in function for two years. A subset of the group was ligated at the gingival sulcus to biologically stress tissues supporting the implants. Crestal bone height around implants was quantified using digital subtraction radiographic techniques. The ligated implants lost more crestal bone than non-ligated implants, as shown by ANOVA (P < 0.05). After retrieval, implants were embedded and sectioned for histomorphometric analysis including measurement of per cent osseointegration. Both plate-form and root-form non-ligated implants demonstrated about 60% osseointegration. When ligated, plate-form implants dropped to an average integration of only 34%, while root-form implants maintained 62% integration, a significant difference. These data show that in this primate model, plate-form and root-form implants maintained integration while in function for two years. When stressed with ligation, root-form implants maintained relative amounts of osseointegration, while per cent osseointegration of plate-form implants decreased.

Comparison of conventional and TACT (Tuned Aperture Computed Tomography) digital subtraction radiography in detection of pericrestal bone-gain

Tuned Aperture Computed Tomography or TACT is a relatively new technique that transforms correlated two-dimensional images into a three-dimensional display. Associating TACT with digital subtraction radiography (TACT-DSR) may enhance its use in the detection of diseases. This study aims to assess observer performance in the task of detecting simulated bone-gain in periodontal defects, comparing conventional and TACT DSR. Buccal, lingual and proximal pericrestal bony defects in a human dry skull were imaged with and without increments of crushed-bone and wax mixtures using standardized vertical bitewing projections, acquired with an intraoral digital receptor in a tomographic X-ray machine. One hundred and twenty pairs of baseline and follow-up images were obtained for each imaging modality. Post-acquisition processing including image-registration, density-correction and subtraction operation were applied to both transmission images and TACT-slices. Eight calibrated observers evaluated the presence or absence of pericrestal bone-gain using a 5-point confidence scale. Details about the location of periodontal defects and the amount of bone-gain for each subtracted image were recorded and used in the statistical analysis. Observer performance and study design factors were analyzed by means of receiver operating characteristic (ROC) curve analysis and ANOVA. Mean values of areas under ROC curves for bone-gain detection performance were 0.82 for conventional DSR and 0.90 for TACT-DSR. TACT-DSR provided statistically superior detection performance of simulated periodontal bone-gain over conventional DSR for tooth-obscured defects (p = 0.001) and for the smallest bone mass (p = 0.024). The findings support TACT-DSR's potential to provide greater sensitivity and technique flexibility in detecting periodontal bone-gain than standard DSR.

[Non-invasive evaluation of an injectable bone substitute]

Despite the increasing number of techniques for the preservation of bone ridges after dental avulsion, no precise evaluation of alveolar filling has been performed to date. The criteria of available measurement techniques (probes, retroalveolar or panoramic radiography, and lateral teleradiography) are not sufficiently reliable and precise. This study investigated the reliability of evaluation based on CT images in comparison with retroalveolar radiography (the most precise radiographic technique, providing standardised images), direct measurements, and images obtained in scanning electron microscopy. After a preliminary investigation ex vivo, a study was performed in vivo on three beagles. Mandibular premolars were extracted, and the corresponding alveoli were filled with an injectable bone substitute composed of a calcium phosphate mineral load associated with hydroxypropyl methylcellulose. Measurements performed on CT images relative to visual and automatic detection of density changes and studies of density curves provided better precision than those obtained by retroalveolar radiography.

Comparison of conventional periodontal maintenance versus scaling and root planing with subgingival minocycline

BACKGROUND

Alternative regimens using subgingival antimicrobials compared to conventional periodontal maintenance (PM) may lead to more efficient protocols. The purpose of this study was to evaluate treatment time and clinical and radiographic outcomes in 2 periodontitis cohorts, one receiving conventional PM and the other receiving scaling and root planing (SRP) and multiple doses of subgingival minocycline.

METHODS

Moderate to advanced chronic periodontitis patients were concurrently treated with either: 1) scaling and root planing and 4 subgingival doses of minocycline microspheres in all > or = 5 mm pockets over a 6-month period (RP/M; n = 24 patients); or 2) conventional 3-month periodontal maintenance (PM; n = 24 patients). Clinical and radiographic measurements, including probing depth (PD), clinical attachment level (CAL), and interproximal bone height (BH), were analyzed in 2 premolar/molar interproximal > or = 5 mm pockets at baseline and 1 year using paired t tests, analysis of variance, chi-square analysis, and correlation coefficients.

RESULTS

Baseline clinical and radiographic data were similar between RP/M and PM patients. Probing depths showed greater mean improvement in RP/M (0.9 +/- 0.1 versus 0.4 +/- 0.1 mm, P = 0.02), with 25% of subjects in RP/M gaining > or = 2 mm compared to 4.2% in PM (differences were statistically significant). The mean loss in bone height and percent subjects losing bone height were less in RP/M (0.05 +/- 0.05 mm; 12.5%) than PM (0.09 +/- 0.08 mm; 16.7%), but bone height differences were not statistically significant. A subset of RP/M molar furcation sites responded with similar PD reduction and no BH loss over 1 year. While cross-sectional RP/M data between CAL and BH, or PD and CAL were highly correlated, changes over 1 year were not correlated among any of these parameters.

CONCLUSIONS

Scaling and root planing and subgingival minocycline in experimental sites took little time (<5 minutes/appointment), but resulted in more probing depth reduction and less frequent bone height loss than conventional periodontal maintenance.

The relationship between skeletal and oral bone mineral density: an overview

Is oral osteopenia (bone loss of the jaws) a component of systemic osteopenia/osteoporosis (systemic bone loss, with or without fracture) or only an accompanying manifestation of periodontal disease? Put other ways: 1) is systemic osteopenia a risk factor for periodontitis; 2) is systemic osteopenia a risk factor for oral osteopenia independent of periodontal disease; or 3) is periodontal disease the primary (exclusive) risk factor for oral osteopenia? Despite 2 decades of scientific inquiry into these questions, the answers remain elusive.

Implants in regenerated bone in a primate model

BACKGROUND

Earlier publications from our laboratory described the use of guided bone regeneration to fill large bone voids in the mandible created through en bloc resection in primates. The present report describes placement of implants into the regenerated bone with subsequent prostheses construction and loading.

METHODS

Lesions were created in the mandibles of 9 monkeys in a standardized mandibular defect of 8 x 19 mm. Reinforced expanded polytetrafluoroethylene membranes were placed in the animals and held in place with mini screws and sutures for anywhere from 1 to 12 months. No material was added to the defect. In each animal a root-form implant was placed 12 mm distal to the abutment teeth into the regenerated bone and was loaded with a prosthesis for 12 months. These implants were compared to original implants placed in the same monkeys years earlier in the same location in non-regenerated bone. Digital radiology and histomorphometry are described.

RESULTS

The results show that root-form implants placed in regenerated bone show the same radiological and histomorphometric characteristics as in normal bone when loaded. In addition, the percentage of bone contact with implants seen in regenerated bone versus non-regenerated bone is the same when both are loaded (65 +/- 13% SD in regenerated bone versus 59 +/- 15% SD in non-regenerated bone).

CONCLUSIONS

In a primate model root-form implants placed in regenerated bone and prosthetically loaded show no difference when compared to root-form implants placed in non-regenerated bone and prosthetically loaded.

Periodontal disease progression

BACKGROUND

The objective of this investigation is to use noninvasive, state-of-the-art, diagnostic techniques to measure periodontal disease progression and model periodontal disease activity over time. In this investigation, digital subtraction radiography and an electronic controlled force periodontal probe capable of attachment level measurement were used to measure bone loss and attachment loss, respectively. The use of these nearly continuous measures of attachment and bone loss allowed detection of small amounts of disease activity and provided data to be used in modeling of the disease process over time.

METHODS

Forty-four patients were studied for 18 months. Examinations used clinical attachment level measures at 1-month intervals and quantitative radiology at 6-month intervals. The sites were analyzed by regression for statistically significant changes. These data were used to determine sites of periodontal disease activity for testing various models of periodontal disease progression.

RESULTS

Overall 22.8% of sites lost attachment, 5.4% gained, and 71.7% demonstrated no statistically significant change. The mean time to lose 1 mm of attachment was 8.4 +/- 0.6 months. In the first model tested a step-wise discriminant analysis was used to determine whether or not baseline measurements of plaque (PI), gingival inflammation (GI), attachment loss, and probing depth (PD) could be used to derive a satisfactory model for disease progression. Although the overall model was statistically significant with PI, PD, and GI contributing to the model (Wilks' lambda = 0.859, F = 5.71, P <0.0012), its predictive power was relatively weak. A considerably stronger significant model resulted when the rate of attachment loss over the first 6 months, baseline PI, and baseline GI were included (Wilks' lambda = 0.712, F = 14.17, P<0.00001). A significant model also resulted when bone loss during the first 6 months and baseline probing depth were included (Wilks' lambda = 0.438, F = 61.48, P<0.00001). When the last model was applied to each site, the sensitivity in predicting disease progression was 80.0% and the specificity in ruling out progressive disease was 93.9%.

CONCLUSIONS

This study indicates that clinically significant progression of attachment loss in posterior tooth sites occurs as a frequent event in adult periodontitis. The modeling data also suggest that short-term (6 month) measures of periodontal disease progression greatly improve the ability to model attachment loss over a longer period in untreated periodontitis patients.

Guided bone regeneration of large mandibular defects in a primate model

BACKGROUND

An earlier publication from our laboratory described the use of guided bone regeneration to fill large bone voids in the mandible created through en bloc resection in primates. The present report is an embellishment of this paper and describes bone regeneration experiments in 18 adult male Macaca mulatta monkeys to determine how long membranes must be in position to promote guided bone regeneration.

METHODS

Thirty-six lesions were created in the mandibles of 18 monkeys in a standardized mandibular defect of 8 x 19 mm. Reinforced ePTFE membranes were placed in the animals and held in place with mini screws and sutures for anywhere from 1 to 12 months. No material was added to the defect. In addition to clinical studies, digital subtraction radiology and fluorescent labeling with tetracycline and histomorphometry are described.

RESULTS

The results indicate that no bone gain was observed in membranes exposed for 1 month or less, but bone gain (approximately well over 90% of defects) was observed at 12 months when membranes were left in situ for 2 to 12 months (P <0.0001). No significant difference in the amount of bone gained at 12 months was observed for membranes left in place for intervals ranging from 2 to 12 months. A significant correlation between the amount of bone gain observed at 3 and 12 months was observed (P <0.0001).

CONCLUSIONS

Data therefore suggest that membranes left in situ for 1 month or less result in minimal bone gain compared with membranes left in place from 2 to 12 months. In addition, labeling and stained sections clearly showed that the bone produced after 2 months of membrane placement is mature.

Analysis of sensitivity and specificity of a new digital subtraction system: an in vitro study

OBJECTIVE

The purpose of this study was to compare a new digital subtraction system with conventional radiograph images for the detection of periapical and periodontal bone lesions.

STUDY DESIGN

Periapical and periodontal bone lesions were simulated with cortical bone chips of varying sizes placed on a human dry mandible. Radiographic film images were acquired from varying projections and were subsequently digitized, registered, and subtracted. Four clinicians evaluated the subtracted images, and sensitivity and specificity were calculated.

RESULTS

The mean sensitivity and specificity of the Diagnostic Subtraction Radiography system for detecting bone lesions of all sizes with varying projection geometry were 87.90% and 85.23%, respectively. The corresponding results for conventional radiograph images were 47.54% and 97.38%. The difference in sensitivity was statistically significant, whereas the difference in specificity was not.

CONCLUSIONS

These results indicate that, even when radiographs are taken from disparate projection geometries, the Diagnostic Subtraction Radiography system is capable of excellent discrimination between healthy and disease states in this in vitro model.

Clinical validation of a new subtraction radiography technique for periodontal bone loss detection

BACKGROUND

Diagnostic subtraction radiography (DSR) is a new digital radiographic image subtraction method designed to enhance detection of crestal or periapical bone density changes and to help evaluate caries progression in teeth. In this clinical study, the performance of the DSR method was evaluated for its ability to detect periodontal bone loss and was compared with that of conventional evaluation of radiographs and the standardized cephalostat-guided image acquisition and subtraction technique (LRA) which served as the "gold standard."

METHODS

In each of 25 subjects with alveolar crestal bone loss created by periodontal surgery, one set of DSR radiographs and one set of LRA radiographs were obtained before and after the surgery. Subtraction images were then generated by both the proprietary DSR and the LRA techniques. Four viewers evaluated the paired film sets and both subtraction image sets using a 5 point confidence scale to determine the presence or absence of crestal bone loss. Receiver operating characteristics (ROC) statistical procedures were applied to analyze the diagnostic accuracy and statistical differences between the three imaging modalities.

RESULTS

The DSR subtraction viewing generated an ROC area of 0.882. For 2 of the viewers this represented a statistically significant gain (P <0.05) over the conventional viewing of the radiographs which had an average ROC area of 0.730. In comparison, the LRA method achieved an area of 0.954. The differences between the LRA and the DSR subtraction methods were not statistically significant, but the statistical power for claiming equality was low ranging from 0.2 to 0.6.

CONCLUSIONS

The use of the DSR technique in clinical radiographic image acquisition and subsequent subtraction analysis clearly enhanced the accuracy of alveolar crestal bone loss detection when compared to conventional film viewing. Because this methodology is less resource demanding than LRA and the film exposure techniques and computer-based image analysis skills may be acquired with only a few hours of training, the DSR has potential in clinical practice.

Radiographic and digital imaging in periodontal practice

This review defines terms such as accuracy, validity, and reliability, which are used to describe the quality of methods for taking x-rays and for analyzing digital images. Values for these parameters are described for techniques of taking standardized x-rays such as ear-rod fixation and fixation by use of teeth with a dental impression. In addition, values are given for linear measurements on digitized images and for quantitative image subtraction. Differences are addressed between quantitative subtraction with a reference ramp and relative subtraction using the computer-assisted densitometric image analysis (CADIA) system. The relationship between radiographic bone height and clinical attachment level is also discussed. Finally, present and future use in the periodontal office of linear radiographic measurements on digital images and digital subtraction is discussed.

Radiographic absorptiometry method in measurement of localized alveolar bone density changes

OBJECTIVE

The objective of this study was to measure the accuracy and precision of a radiographic absorptiometry method by using an occlusal density reference wedge in quantification of localized alveolar bone density changes.

STUDY DESIGN

Twenty-two volunteer subjects had baseline and follow-up radiographs taken of mandibular premolar-molar regions with an occlusal density reference wedge in both films and added bone chips in the baseline films. The absolute bone equivalent densities were calculated in the areas that contained bone chips from the baseline and follow-up radiographs. The differences in densities described the masses of the added bone chips that were then compared with the true masses by using regression analysis.

RESULTS

The correlation between the estimated and true bone-chip masses ranged from R = 0.82 to 0.94, depending on the background bone density. There was an average 22% overestimation of the mass of the bone chips when they were in low-density background, and up to 69% overestimation when in high-density background. The precision error of the method, which was calculated from duplicate bone density measurements of non-changing areas in both films, was 4.5%.

CONCLUSIONS

The accuracy of the intraoral radiographic absorptiometry method is low when used for absolute quantification of bone density. However, the precision of the method is good and the correlation is linear, indicating that the method can be used for serial assessment of bone density changes at individual sites.

Use of a biodegradable chlorhexidine chip in the treatment of adult periodontitis: clinical and radiographic findings

BACKGROUND

Previous multi-center trials demonstrated the efficacy of a biodegradable chlorhexidine-gelatin chip (CHX) in reducing probing depth in patients with periodontitis. The present study utilized a subset of subjects from the parent study to determine if the CHX chip was effective in maintaining alveolar bone over a 9-month period.

METHODS

Forty-five subjects with at least four 5 to 8 mm pockets, stratified by smoking status, were enrolled in this double-blind controlled, placebo-controlled trial. Control groups received either placebo chip plus scaling and root planing (SRP) or SRP alone. Test group subjects received active CHX chip or SRP alone (to maintain the blind). Standardized radiographs were taken for quantitative digital subtraction radiography at baseline and 9 months.

RESULTS

At 9 months, 15% of SRP treated subjects experienced loss of bone in 1 or more sites, no subject treated with active chip plus SRP lost bone (P <0.01). At 9 months, significant differences in the change in probing depth and clinical attachment levels favoring the active chip over SRP alone or SRP plus CHX chip were also observed (P <0.05).

CONCLUSIONS

These data indicate that the CHX chip, when used as an adjunct to scaling and root planing, significantly reduces loss of alveolar bone.

Progression and treatment of chronic adult periodontitis

BACKGROUND

The periodontal status of 41 medically healthy adults with untreated chronic periodontitis was monitored before and after scaling and root planing (SRP).

METHODS

During a 6-month pretreatment phase, clinical measurements, digital subtraction radiography (DSR) analysis of alveolar bone, and measurement of gingival crevicular fluid (GCF) prostaglandin E2 (PGE2) levels were undertaken. SRP was provided during a 1-month treatment phase. Clinical, radiographic, and biochemical analyses were repeated in a 6-month post-treatment healing period.

RESULTS

Pretreatment: no clinically significant changes in mean plaque indices (PI), probing depths (PD), bleeding on probing (BOP), or relative clinical attachment levels (CAL) were detected (P>0.05). DSR revealed small but statistically significant bone height (0.04 mm) and mass (0.97 mg) loss (P<0.001). GCF PGE2 levels gradually increased from 38.8 ng/ml at month 1 to 79.4 ng/ml at month 6. Post-treatment: statistically and clinically significant reductions were observed in mean PI, BOP, and PD (P<0.05). A statistically significant reduction in CAL was noted (P<0.05). The trend towards progressive bone loss was halted and reversed, and a statistically significant decrease in GCF PGE2 concentrations was detected (P<0.001). Smokers, non-smokers, and ex-smokers did not differ significantly in PI, BOP, CAL, radiographic, or biochemical parameters at any time. Mean PD was significantly greater in current smokers than in non- and ex-smokers (P<0.005). PD reduced comparably in all 3 smoking subgroups following treatment (P<0.01).

CONCLUSIONS

Conventional clinical measurements failed to identify disease progression over a 6-month period. Significant improvements were observed in clinical parameters after SRP, and a trend towards progressive bone loss was halted and reversed. Regular and frequent maintenance visits are important following treatment to maintain improvements in clinical parameters. Smokers had deeper probing depths than non- and ex-smokers, but pockets were reduced significantly and comparably in all 3 smoking subgroups following efficacious treatment.

Host responses to recombinant hemagglutinin B of Porphyromonas gingivalis in an experimental rat model

Porphyromonas gingivalis, a gram-negative, black-pigmented anaerobe, is among the microorganisms implicated in the etiology of adult periodontal disease. This bacterium possesses a number of factors, including hemagglutinins, of potential importance in virulence. Several hemagglutinin genes have been identified, cloned, and expressed in Escherichia coli. The purpose of this study was to characterize host responses to purified recombinant hemagglutinin B (rHag B), using the conventional Fischer rat as the experimental animal model. The effectiveness of immunization with rHag B on protection against experimental periodontal bone loss following infection with P. gingivalis was also evaluated. Groups of rats were immunized by the subcutaneous route with rHag B in complete Freund's adjuvant, immunized with rHag B and orally infected with P. gingivalis, nonimmunized and noninfected, or orally infected with P. gingivalis only. Serum and saliva samples were collected throughout the experiment and evaluated for serum immunoglobulin G (IgG) and IgM and salivary IgA antibody activity by enzyme-linked immunosorbent assay. No salivary IgA anti-Hag B activity was detected in the various groups of rats. A slight serum IgM response similar to that seen in preimmune samples was observed. Serum IgG antibody activity to Hag B was detected only in samples from rats immunized with rHag B. This response was primarily of the IgG1 and IgG2a subclasses, followed by IgG2b and low levels of IgG2c. Supernatants from rHag B-stimulated splenic lymphoid cell cultures from immunized rats contained high levels of gamma interferon, followed by interleukin-2 (IL-2), IL-10, and then IL-4. These results are consistent with the induction of T helper type 1 (Th1)- and Th2-like responses. Western blot analysis of sera derived from rHag B-immunized rats reacted with trichloroacetic acid (TCA) precipitates of P. gingivalis 33277, 381, A7A1-28, and W50, revealing a 50-kDa band reflective of Hag B. However, sera derived from rats immunized with P. gingivalis whole cells or from rats infected with P. gingivalis only did not react with rHag B but did react with TCA precipitates of P. gingivalis strains. Finally, radiographic measurements of periodontal bone loss indicated that rats immunized with rHag B had less bone loss than those infected with P. gingivalis only. These results demonstrate the effectiveness of purified rHag B in inducing a protective immune response and support the potential usefulness of this component of P. gingivalis in the development of a vaccine against adult periodontitis.

Radiographic determinants of implant performance

This paper reviews and compares the strengths and weaknesses of radiographic techniques including periapical, occlusal, panoramic, direct digital, motion tomography, and computed tomography. Practical considerations for each method, including availability and accessibility, are discussed. To date, digital subtraction radiography is the most versatile and sensitive method for measuring boss loss. It can detect both bone height and bone mass changes on root-form or blade-form dental implants. Criteria for implant success have changed substantially over the past two decades. In clinical trials of dental implants, the outcomes require certain radiographic analyses to address the hypothesis or clinical question adequately. Radiographic methods best suited to the objective assessment of implant performance and hypothesis were reviewed.