Dosimetric evaluation of LINAC-based single-isocenter multi-target multi-fraction stereotactic radiosurgery with more than 20 targets: comparing MME, HyperArc, and RapidArc

BACKGROUND

To compare the dosimetric quality of three widely used techniques for LINAC-based single-isocenter multi-target multi-fraction stereotactic radiosurgery (fSRS) with more than 20 targets: dynamic conformal arc (DCA) in BrainLAB Multiple Metastases Elements (MME) module and volumetric modulated arc therapy (VMAT) using RapidArc (RA) and HyperArc (HA) in Varian Eclipse.

METHODS

Ten patients who received single-isocenter fSRS with 20-37 targets were retrospectively replanned using MME, RA, and HA. Various dosimetric parameters, such as conformity index (CI), Paddick CI, gradient index (GI), normal brain dose exposures, maximum organ-at-risk (OAR) doses, and beam-on times were extracted and compared among the three techniques. Wilcoxon signed-rank test was used for statistical analysis.

RESULTS

All plans achieved the prescribed dose coverage goal of at least 95% of the planning target volume (PTV). HA plans showed superior conformity compared to RA and MME plans. MME plans showed superior GI compared to RA and HA plans. RA plans resulted in significantly higher low and intermediate dose exposure to normal brain compared to HA and MME plans, especially for lower doses of ≥ 8Gy and ≥ 5Gy. No significant differences were observed in the maximum dose to OARs among the three techniques. The beam-on time of MME plans was about two times longer than RA and HA plans.

CONCLUSIONS

HA plans achieved the best conformity, while MME plans achieved the best dose fall-off for LINAC-based single-isocenter multi-target multi-fraction SRS with more than 20 targets. The choice of the optimal technique should consider the trade-offs between dosimetric quality, beam-on time, and planning effort.

Acceptance and awareness of southeastern and western private practice pediatric dentists of fluoride-free toothpastes: a survey study

The American Academy of Pediatric Dentistry (AAPD) affirms that the use of fluoride, as an adjunct in the prevention of caries, is safe and effective. The AAPD encourages dentists, other healthcare providers, and parents to optimize fluoride exposures to reduce the risk of caries and to enhance the remineralization of affected teeth. However, there is resistance amongst patients towards fluoride overexposure and despite there being research on other effective remineralizing agents, most pediatric dentists primarily cater their practice to fluoride-based products. The objective of the study is to survey pediatric dentists' acceptance and awareness of fluoride-free remineralizing agents. A listserv of the southeastern and western private practice pediatric dentists was obtained from the AAPD consisting of 6490 email addresses. A questionnaire consisting of 15 questions was sent to each address using Qualtrics. Different trends in fluoride-free acceptance and awareness were seen based on region of practice, region of training and age of practitioner. Region of practice, residency training and age can be contributing factors toward fluoride-free remineralizing agent opinion. The data gathered trends towards western-trained pediatric dentists are more likely to recommend a fluoride-free toothpaste than a southeastern-trained dentist.

Cognitive and neuroimaging outcomes in individuals with benign and low-grade brain tumours receiving radiotherapy: a protocol for a prospective cohort study

INTRODUCTION

Radiation-induced cognitive decline (RICD) occurs in 50%-90% of adult patients 6 months post-treatment. In patients with low-grade and benign tumours with long expected survival, this is of paramount importance. Despite advances in radiation therapy (RT) treatment delivery, better understanding of structures important for RICD is necessary to improve cognitive outcomes. We hypothesise that RT may affect network topology and microstructural integrity on MRI prior to any gross anatomical or apparent cognitive changes. In this longitudinal cohort study, we aim to determine the effects of RT on brain structural and functional integrity and cognition.

METHODS AND ANALYSIS

This study will enroll patients with benign and low-grade brain tumours receiving partial brain radiotherapy. Patients will receive either hypofractionated (>2 Gy/fraction) or conventionally fractionated (1.8-2 Gy/fraction) RT. All participants will be followed for 12 months, with MRIs conducted pre-RT and 6-month and 12 month post-RT, along with a battery of neurocognitive tests and questionnaires. The study was initiated in late 2018 and will continue enrolling through 2024 with final follow-ups completing in 2025. The neurocognitive battery assesses visual and verbal memory, attention, executive function, processing speed and emotional cognition. MRI protocols incorporate diffusion tensor imaging and resting state fMRI to assess structural connectivity and functional connectivity, respectively. We will estimate the association between radiation dose, imaging metrics and cognitive outcomes.

ETHICS AND DISSEMINATION

This study has been approved by the Research Subjects Review Board at the University of Rochester (STUDY00001512: Cognitive changes in patients receiving partial brain radiation). All results will be published in peer-reviewed journals and at scientific conferences.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT04390906.

New dosimetric guidelines for linear Boltzmann transport equations through comparative evaluation of stereotactic body radiation therapy for lung treatment planning

Purpose

To propose guidelines for lung stereotactic body radiation therapy (SBRT) when using Acuros XB (AXB) equivalent to the existing ones developed for convolution algorithms such as analytic anisotropic algorithm (AAA), considering the difference between the algorithms.

Methods

A retrospective analysis was performed on 30 lung patients previously treated with SBRT. The original AAA plans, which were developed using dynamic conformal arcs, were recalculated and then renormalized for planning target volume (PTV) coverage using AXB. The recalculated and renormalized plans were compared to the original plans based on V100% and V90% PTV coverage, as well as V105%, conformality index, D_2cm, Rx/D_max, R50, and D_min. These metrics were analyzed nominally and on variations according to RTOG and NRG guidelines. Based on the relative difference between each metric in the AAA and AXB plans, new guidelines were developed. The relative differences in our cohort were compared to previously documented AAA to AXB comparisons found in the literature.

Results

AAA plans recalculated in AXB had a significant reduction in most dosimetric metrics. The most notable changes were in V100% (4%) and the conformality index (7.5%). To achieve equal PTV coverage, AXB required an average of 1.8% more monitor units (MU). This fits well with previously published data. Applying the new guidelines to the AXB plans significantly increased the number of minor violations with no change in major violations, making them comparable to those of the original AAA plans.

Conclusion

The relative difference found between AAA and AXB for SBRT lung plans has been shown to be consistent with previous works. Based on these findings, new guidelines for lung SBRT are recommended when planning with AXB.

Crustal structure of Sicily from modelling of gravity and magnetic anomalies

We aim at modeling the main crustal and thermal interfaces of Sicily (Italy), a key area for understanding the geological complexity at the collisional boundary between the African and European plates. To this end, we analyze the gravity and magnetic fields, integrated with information from well logs, geology, heat flow, and seismic data. In order to make the most accurate description of the crustal structure of the area, we modeled with different methodologies the carbonate and crystalline top surfaces, as well as the Moho and the Curie isotherm surface. The reconstruction of the carbonate platform is achieved using a nonlinear 3D method constrained by the available seismic and borehole data. The crystalline top, the Curie, and the Moho are instead estimated by spectral analysis of both gravity and magnetic data. The results show a complex carbonate basement and a deep crystalline crust in central Sicily, with a prominent uplift beneath the Hyblean Plateau. Maps of the Moho and the Curie isotherm surface define a variable thermal and structural setting of Sicily, with very thin crust in the southern and eastern sectors, where high heat flow is found, and deep and cold crust below the Caltanissetta Basin.

QOLP-26. PATIENT REPORTED SOCIAL FUNCTION AND SURVIVAL IN GLIOMA PATIENTS

PURPOSE

Research among patients with cancer suggests that health related quality of life (HRQOL) may be more predictive of survival than performance status. Social function is a HRQOL outcome influenced by both physical and mental health. To our knowledge, no work has analyzed the potential association between survival and social function in patients with brain tumors.

METHODS

In the SEER Medicare Health Outcomes Survey, 158 patients were identified with 1) diagnosis of glioma between 1976 and 2013 2) no other cancer diagnosis 3) at least one post-diagnosis HRQOL survey. We examined the relationship between social function and mortality using a multivariable Cox proportional hazard model. We also examined factors correlated with social function score using linear regression.

RESULTS

At last follow up, 48% of the patients had died, 53% were female, 59% had trouble with ≥1 ADL, 53% were married, 27% had glioblastoma, 74% were white, and 32% had no reported comorbidities. Median time from cancer diagnosis to survey was 79 months and median age at survey was 60 years. For patients alive at last follow-up, there was a difference of >5 points for the social function subscale (38.2 vs 30.6) compared to those who died during the median 163 month follow up interval. On multivariable Cox proportion hazard model adjusting for covariates, higher social function scores were significantly associated with improved survival (5 point increase in score, HR 0.86, p = 0.0029). Worse social function was associated with patient-reported neurologic deficits in vision and speech and report of depression, but not marital status, sex, race, or patient-reported income.

DISCUSSION

Patient-reported social function score on post-diagnosis surveys, even after accounting for important clinical factors, was significantly associated with survival. The impact of patient reported social function in those with glioma should be further examined in confirmatory longitudinal studies.

INNV-09. CLINICAL EFFICACY OF TUMOR TREATING FIELDS FOR NEWLY DIAGNOSED GLIOBLASTOMA

Recent clinical trials demonstrated that adding tumor treating fields (TTF) to radiotherapy and temozolomide chemotherapy (the Stupp protocol) increased survival for glioblastoma (GBM) patients. However, data is lacking on the magnitude of this survival effect when the regimen is used outside of a clinical trial as part of routine clinical practice. In the present study, we retrospectively identified adult patients with newly diagnosed GBM (n = 240) treated with the Stupp protocol at our institution from January 2005 to July 2017. We grouped patients into two time periods for comparison: 2005–2013 (group 1, Stupp protocol) and 2014–2017 (group 2, TTF+ Stupp protocol). Thirty-six percent (37/104) of patients in group 2 received TTF in conjunction with the Stupp protocol. Within group 2, the 37-patients who received TTF + Stupp had increased 6-month and 1-year survival rates compared to the 67-patients who received Stupp alone (97.1% vs. 75.7%, p = 0.006; 67.6% vs. 53.7%, p = 0.170, respectively). The improvement of survival rate at 6-month was further confirmed by a modified Poisson model (RR: 1.23, p = 0.010) adjusting for sex, age, performance status and extent of resection. However, we did not observe improvements in overall survival (OS) with a Cox model with TTF treatment modeled as a time-dependent covariate (HR = 0.87, p = 0.599). Furthermore, we did not find that the addition of TTF as a treatment option in our center significantly improved OS for patients in group 2 when compared to those in group 1 (429.0 vs. 395.0 days, p = 0.138). Therefore, while adding TTF to the Stupp protocol appeared to benefit patients with newly diagnosed GBM, this effect may be largely due to selection bias. Comprehensive studies including large number of patients as well as longer follow-up time are needed to validate our results.

Time-course of transcriptome response to respiratory syncytial virus infection in lung epithelium cells

Respiratory syncytial virus (RSV) is the major cause of acute lower respiratory tract infection in infants. Winter outbreaks in Chile result in 5% of infected children hospitalized, with 0.01% mortality. Increased evidence indicates that viral and host factors modulate the severity of infection. Using DNA microarrays, we characterized the genome-wide transcriptional response of lung mucoepidermoid cells (NCI-H292) at 0, 24, 48, 72 and 96 hours post-infection (hpi) with a single dose of RSV/A. During the whole studied period, a bi-phasic gene expression profile was observed by a total of 330 differentially expressed genes. About 60% of them were up-regulated between 24-72 hpi and then turned-off at 96 hpi. This transient, early gene expression pattern was significantly enriched in biological processes like interferon signaling, antigen processing and presentation, double-stranded RNA binding and chemokine activity. We detected 27 common genes up-regulated between 24-72 hpi, from which IFIT1, IFI44, MX1, CXCL11 and OAS1 had the highest expression. The second pattern comprised over 120 genes, which remained silenced until 72 hpi, but were steeply up-regulated by 96 hpi. Biological processes of this late-response profile included cell cycle division and microtubule cytoskeleton organization. Conversely, the genes belonging to virus response pathway showed a decreased expression at 96 hpi. We conclude that RSV induces an early innate immune activation profile response until 72 hpi. Thereafter, the viral response is inhibited, leading to host cell recovery. The presented cellular model allows to study the specific pathways involved in elimination of infection at prolonged time intervals and their subsequent analysis in severe RSV disease of infants and/or older adults.

Oral Healthcare for Persons With Intellectual or Developmental Disabilities: Why Is There a Disparity?

Despite some progress, a significant disparity still exists in oral healthcare between individuals with intellectual or developmental disabilities and the general population. Barriers generated by finances, a lack of appropriately trained dental providers, and the patients themselves combine to create significant challenges to providing dental care. However, strategies exist that can help to decrease the magnitude of these hurdles so this disparity can be minimized.

Erythropoietin and neuroprotection: a therapeutic perspective

Recombinant erythropoietin (EPO) is used to correct for anaemia caused by chronic renal failure or cancer therapy. Improvement of the quality of life of anaemic patients treated with EPO was recently demonstrated and preliminary clinical results suggest an improvement of cognitive functions in patients receiving EPO. High expression of EPO and its receptor in the brain during embryonic development has led to the investigation of not only the neurotrophic role of EPO but also its neuroprotective properties. The neuroprotective effects of EPO have various complementary actions including antagonism of the effects of glutamate, increased expression of antioxidant enzymes, changes in production of neurotransmitters and induction of neuroglobin. Convincing experimental results suggest a blood-brain transport of EPO whereas clinical pharmacokinetic data do not as yet support this. The neuroprotective effects of EPO and its therapeutic promise need to be underlined.

Particulate matter phagocytosis induces tissue factor in differentiating macrophages

Airborne exposure to particulate matter with diameter < 10 mcM (PM10) has been linked to an increased risk of thromboembolic events, but the mechanisms are not completely understood. The aim of this study was to evaluate the effect of PM10 phagocytosis on the release of procoagulant molecules in human differentiating macrophages, and that of PM10 inhalation in an experimental model in rats. Human monocytes were separated from the peripheral blood by the lymphoprep method, differentiated in vitro and treated with standard PM10 or vehicle. Sprague-Dawley rats were instilled intratracheally with PM10 or vehicle alone. The outcome was expression of proinflammatory genes and of tissue factor (TF). In human differentiating macrophages, PM10 exposure upregulated inflammatory genes, but most consistently induced TF mRNA and protein levels, but not TF protein inhibitor, resulting in increased TF membrane expression and a procoagulant phenotype. Differentiation towards the anti-inflammatory M2 phenotype inhibited PM10 -mediated TF expression. TF induction required phagocytosis of PM10 , whereas phagocytosis of inert particles was less effective. PM10 phagocytosis was associated with a gene expression profile consistent with intracellular retention of iron, inducing oxidative stress. Both PM10 and iron activated the stress kinases ERK1/2 pathway, involved in the induction of TF expression. In rats, alveolar exposure to PM10 was associated with pulmonary recruitment of inflammatory cells and resulted in local, but not systemic, induction of TF expression, which was sufficient to increase circulating TF levels. In conclusion, TF induction by differentiating lung macrophages, activated following phagocytosis, contributes to the increased risk of thromboembolic complications associated with PM10 exposure.

Abstract P4-01-21: Head to head comparison of standard echo doppler versus 3D speckle tracking echocardiography for early subclinical cardiotoxicity detection in breast cancer patients treated with anthracycline adjuvant chemotherapy

Background. Anthracycline (ANT)-containing regimens represent the prevalent choice for adjuvant therapy in early breast cancer (EBC) patients. However, cardio toxicity is a major limitation, strongly affecting the quality of life and the overall survival of cancer patients, regardless of the oncologic prognosis.

Aims: To assess the diagnostic power of real-time 3D Speckle Tracking Echocardiography (STE) in comparison with standard echo Doppler (SED) in detection of early subclinical ANT related cardio toxicity in breast cancer patients.

Methods: Fifty-five consecutive patients (F/M = 54/1, mean age = 48 years) with EBC were prospectively enrolled in the study. All patients received three cycles of epirubicin (EPI) based chemo regimen followed by taxanes. Overall, average EPI cumulative dose per patient was 505 ± 68 mg/m2 (range = 360-720 mg/m2). Complete SED exam including determination of 2D ejection fraction (EF) and pulsed Tissue Doppler of the mitral annulus were measured at baseline and at the end of the three cycles of EPI. Three-D determination of left ventricular volumes and EF as well as 3D STE-derived global longitudinal strain (GLS), global circumferential strain (GCS), global area strain (GAS) and global radial strain (GRS) were assessed, whenever feasible, at the same time points.

Results: All the patients completed the three cycles of EPI as per protocol. No overt clinical manifestation of heart failure was observed. Standard echo doppler was performed in all the patients. Two-D EF did not significantly change with EPI treatment. However, the E/e’ ratio measured by SED, was significantly increased after EPI administration (6.7±1.7 vs. 7.25±1.8 before and after treatment, respectively; p&lt;0.05). Overall, 3D ventricular volumetric assessment was feasible in the 63.6% (35/55) of patients and 3D STE in the 60% (33/55) of patients due to anatomical or technical problems. Among parameters measured by 3D STE, a reduction of EF (58.8±8% vs. 61.7±7.1%, before and after treatment, respectively; p&lt;0.02) and a significant increase of the left ventricular end-systolic volume (p&lt;0.01) was observed. Importantly, a significant decrease of the following 3D STE parameters: GLS (p&lt;0.01), GRS (p&lt;0.001), GCS (p&lt;0.0001) and GAS (p&lt;0.0001) were observed after EPI therapy.

Conclusions: Results from the present study confirm the increased sensitivity of real time 3D STE technique in detecting early subclinical signs of cardio toxicity in patients with EBC treated with EPI adjuvant chemotherapy. However, due to technical problems, STE was not feasible in the entire patient population included in the study. Among parameters measured by SED, the E/e’ ratio identifies early signs of cardiac dysfunction more accurately compared to the standard 2D EF determination.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-01-21.

Unmet dental needs and barriers to dental care among children with autism spectrum disorders

Mail-in pilot-tested questionnaires were sent to a stratified random sample of 1,500 families from the North Carolina Autism Registry. Multivariate logistic regression analysis was used to determine the significance of unmet dental needs and other predictors. Of 568 surveys returned (Response Rate = 38%), 555 were complete and usable. Sixty-five (12%) children had unmet dental needs. Of 516 children (93%) who had been to a dentist, 11% still reported unmet needs. The main barriers were child's behavior, cost, and lack of insurance. The significant predictor variables of unmet needs were child's behavior (p = 0.01), child's dental health (p < 0.001), and caregiver's last dental visit greater than 6 months (p = 0.002). Type of ASD did not have an effect on having unmet dental needs.

Multicenter results of stereotactic body radiotherapy (SBRT) for non-resectable primary liver tumors

BACKGROUND

An excess of 100 000 individuals are diagnosed with primary liver tumors every year in USA but less than 20% of those patients are amenable to definitive surgical management due to advanced local disease or comorbidities. Local therapies to arrest tumor growth have limited response and have shown no improvement on patient survival. Stereotactic body radiotherapy (SBRT) has emerged as an alternative local ablative therapy. The purpose of this study was to evaluate the tumor response to SBRT in a combined multicenter database.

STUDY DESIGN

Patients with advanced hepatocellular carcinoma (HCC, n = 21) or intrahepatic cholangiocarcinoma (ICC, n = 11) treated with SBRT from four Academic Medical Centers were entered into a common database. Statistical analyses were performed for freedom from local progression (FFLP) and patient survival.

RESULTS

The overall FFLP for advanced HCC was 63% at a median follow-up of 12.9 months. Median tumor volume decreased from 334.2 to 135 cm(3) (p < 0.004). The median time to local progression was 6.3 months. The 1- and 2-years overall survival rates were 87% and 55%, respectively. Patients with ICC had an overall FFLP of 55.5% at a median follow-up of 7.8 months. The median time to local progression was 4.2 months and the six-month and one-year overall survival rates were 75% and 45%, respectively. The incidence of grade 1-2 toxicities, mostly nausea and fatigue, was 39.5%. Grade 3 and 4 toxicities were present in two and one patients, respectively.

CONCLUSION

Higher rates of FFLP were achieved by SBRT in the treatment of primary liver malignancies with low toxicity.

Dental implications of osteogenesis imperfecta: treatment with IV bisphosphonate: report of a case

Osteogenesis imperfect (OI) is a group of genetically diverse connective tissue disorders. Bisphosphonates therapy to manage bone fragility, a now common medical therapy for OI, can increase the risk of bisphosphonate-associated osteonecrosis of the jaws. In this report, a 6 ½ year child, who was receiving bisphosphonate therapy for OI, underwent full mouth dental rehabilitation in the operating room while under general anesthesia. The child had numerous teeth restored and multiple primary molar extractions. The patient, who received prophylactic antibiotics intraoperatively, demonstrated no clinical signs of bisphosphonate-associated osteonecrosis when seen at follow-up. Although bisphosphonate osteonecrosis is a possible sequel in children who receive multiple extractions, no clinical signs were manifested in our patient, who required multiple primary tooth extractions along with restorative treatment under general anesthesia. While no dental guidelines have been developed to manage OI children having been treated with bisphosphonates, consent for extractions should include the risk of bone necrosis and careful post-operative observation to monitor wound healing.

Recent advances in targeted therapies for colorectal cancer

BACKGROUND

Recent advances in the molecular biology and genetics of colorectal cancer have led to the identification of potential therapeutic targets such as epidermal growth factor receptor, vascular endothelial growth factor and endothelial receptors.

OBJECTIVE

This review will examine the major therapeutic advances along with the preclinical basis justifying their combination with conventional therapeutic tools. This review will also critically consider current possibilities offered to identify responding patients.

DATA SOURCES

Preclinical and primary clinical trial results published in peer-review journals. The authors examined the relevance and subsequent inclusion of the data.

CONCLUSIONS

Cetuximab and bevacizumab provide new benefits in terms of the response rate and survival. There remain, however, important questions concerning, for instance, optimal combinations between conventional cytotoxic agents and targeted therapies and also between targeted drugs themselves. These new targeted treatments are costly and in this context the question of the identification of the right drug for the right patient is particularly relevant. Adequate tools in predicting the efficacy of targeted treatments are still needed.

A cross-sectional study of medication-related factors and caries experience in asthmatic children

PURPOSE

The purpose of this study was to examine the relationship between the specific types of medication, length of use, frequency of use, and dosing time of day on the dental caries of children diagnosed with asthma.

METHODS

Using a patient list from a previous study, surveys were mailed to the parents of 179 asthmatic children. The survey itself consisted of a table that asked 4 questions: (1) What combination of asthma medications was used by the subject? (2) How long were the medications used? (3) How often were the medications used? (4) What time of day were the medications used?

RESULTS

Of the 179 surveys that were mailed out, 156 were returned. Children who used their medication greater than twice daily were significantly more likely to experience dental disease in both the primary (odds ratio [OR]=2.56, 95% confidence interval [CI]=1.45-6.29) and mixed dentitions (OR=3.56, 95% CI 2.45-5.94).

CONCLUSIONS

Increased frequency of asthma medication use was associated with increased likelihood of caries experience. The time of day asthma medication was used was associated with increased likelihood of caries experience in children in the primary dentition. Duration of asthma medication use was associated with a decreased likelihood of caries experience in children in the mixed dentition.

Le récepteur à l'EGF et les cancers des voies aérodigestives supérieures

EGFR is overexpressed and is associated with a poor prognosis in head and neck cancer. Among the biological and cellular effects resulting from EGFR targeting in head and neck cancer there is the capacity to restore apoptotic capacities. Other experimental results put into evidence that DNA-repair activity was reduced by the application of EGFR targeting agents. This context was in favor of a research oriented towards combination between anti-EGFR drugs and cytotoxic agents, particularly irradiation. Supra-additive cytotoxic effects have been observed at the experimental level when combining anti-EGFR drugs with irradiation in head and neck cancer. These experimental data were recently confirmed at the clinical level in locally advanced head and neck cancer.

Dental students' experiences with and attitudes toward people with mental retardation

BACKGROUND

People with mental retardation have limited access to oral health care. Dental school administrators reported minimal training in U.S. dental schools for these patients. As a result, students and practitioners may not be prepared to provide needed services.

METHODS

The authors surveyed 295 third- and fourth-year students at five dental schools about their didactic and clinical preparation for, attitudes toward and comfort levels with treating people with mental retardation, as well as whether their experiences affect their willingness to treat people with mental retardation. The authors analyzed data using previously developed statistical software.

RESULTS

A little more than 68 percent of respondents reported receiving five hours or less of instruction devoted to how to care for people with mental retardation, and 50.8 percent reported having no clinical training in this area. Nearly 60 percent reported that they had little to no confidence in providing care, while 74.6 percent reported they had little to no preparation in providing care. Students who had experience working with people with mental retardation attributed greater capabilities to such people than did students who had no such experience.

CONCLUSIONS

Many U.S. dental students are prepared inadequately to provide services for people with mental retardation. Spending time with these patients provides a more positive understanding of the capabilities of these people.

PRACTICE IMPLICATIONS

Increasing numbers of people with mental retardation no longer live in institutions, and they are dependent on dentists in private practice for care. Increased dental school training and continuing education programs are needed to meet this need.

Fluoride-releasing resin bonding of amalgam restorations in primary teeth: in vitro secondary caries effect

PURPOSE

To evaluate the effects of a fluoride-releasing resin designed for amalgam bonding on secondary caries formation in primary teeth restored with amalgams.

MATERIALS AND METHODS

Primary teeth with caries-free buccal and lingual surfaces were selected and underwent a fluoride-free prophylaxis. Cavity preparations were performed in the buccal and lingual smooth surfaces of 20 primary teeth. A fluoride-releasing dimethacrylate resin bonding agent (Alloybond) was placed prior to amalgam restoration (Dispersalloy) of the cavity preparations in 10 teeth. Amalgam restorations placed in 10 teeth following copal cavity varnish (Copalite) served as controls. The teeth were thermocycled in synthetic saliva (500 cycles, 5 degrees-50 degrees C), and then coated with an acid-resistant coating, leaving a 1mm rim of sound enamel surrounding the restorations. Artificial secondary caries were created (2.2 mM calcium, 2.2 mM phosphate, 50 mM acetic acid, 0.5 ppm fluoride, pH 3.90). Following lesion formation, longitudinal sections (five per tooth) were prepared for polarized light evaluation. Mean depths for the primary surface lesions were determined using a computer-interfaced digitized tablet. Cavity wall lesion frequencies were also evaluated. Comparisons were made between groups (ANOVA, DMR).

RESULTS

Primary surface lesion depth was reduced significantly (P < 0.05) with Alloybond-amalgams (135 +/- 14 microm) when compared with Copalite-amalgams (184 +/- 21 microm). Cavity wall lesion frequency was decreased (P < 0.05) significantly with Alloybond-amalgams (57%) compared with Copalite-amalgams (89%). The beneficial effect of the fluoride-releasing amalgam bonding agent was not limited to the cavosurface enamel. The caries susceptibility of enamel surfaces adjacent to amalgams with the fluoride-releasing bonding agent was decreased considerably. The incorporation of the amalgam-bonding resin with fluoride-releasing capabilities provided greater protection against a constant cariogenic attack over that for a conventional amalgam restoration.

Mucosal calcified nodule of the gingiva in an infant

The mucosal calcified nodule is a rare oral lesion that has a predilection for the young child. This case report describes an infant with a persistent and tender gingival swelling associated with an unerupted, maxillary central incisor. Besides a differential diagnosis for this entity, the causes of abnormal calcium deposits within the skin of children are discussed.

Dental care for special needs patients: a survey of Texas pediatric dentists

The purpose of this study was to determine the amount of time Texas pediatric dentists spent, as both residents and in their professional position, in the treatment of special needs patients. In addition, an attempt was made to determine the dental services offered to these patients along with the barriers to obtaining care. A survey was mailed to the 334 members of the Texas Academy of Pediatric Dentistry. From the returned surveys (61.9% or 207/334) the following conclusions were drawn: 1) Most respondents had a significant portion of their training program devoted to special patient care, 2) Virtually all reported treating some special needs patients in their professional position, 3) Most provided conscious sedation and general anesthesia and adjuncts to behavior management for these patients, 4) Insufficient financial reimbursement was a major reason cited for not providing dental services to more of these patients.

Multi-rooted mandibular premolars: report of case

Differential growth of the epithelial diaphragm is needed for the formation of multiple roots in the primary and permanent dentitions. In most instances, the mandibular premolars possess a single root. It is a very unusual event to find a case of bilateral multi-rooted first and second mandibular premolars. This paper presents such a case.