In vitro and in vivo feasibility study of ultrasound for monitoring tooth surface loss

This work attempted to appraise the usefulness of ultrasound as a diagnostic tool for use in dentistry. A number of possibilities were modelled and the most promising, at this time, was monitoring tooth surface loss (TSL). TSL is a serious dental condition affecting patients worldwide. Current methods used to monitor TSL in the dental surgery are subjective and unreliable. Laboratory-based monitoring methods are time consuming and costly. Ultrasound is a non-invasive, non-destructive method that is mainly used in the medical field. Its use in dentistry started in the 1950s but is still limited to therapeutics (e.g. periodontics and endodontics) and head and neck imaging. There are several modes of ultrasound imaging. Of particular note are amplitude mode (A-mode) and brightness mode (B-mode) ultrasound. In A-mode, a single beam is sent to an object, and its reflected echo is captured. This mode does not produce an image but is rather displayed as a waveform in time and amplitude domains. B-mode ultrasound has two spatial axes and therefore is used as a cross-sectional imaging tool. To date, there are no in vivo studies investigating the use of ultrasound to directly monitor TSL in the dental surgery. The aim of this thesis was to assess the feasibility and optimisation of ultrasound as a potential clinical dental tool in monitoring erosive TSL in vivo. This thesis investigated the coupling efficiency of various dental and other materials and their suitability as couplants. The results showed that Perspex was a suitable ultrasonic couplant for the purpose of enamel thickness measurements and the tightness of the coupling at an interface was of importance for efficient transmission of ultrasound energy into an object. However, a purpose-built apparatus was required for this as the ultrasound echoes were angle dependent. It further investigates the angle dependency of echoes arising from premolars compared to synthetic maxillary central incisors, as natural incisors were not available. The results demonstrated that the more planar incisors reflected ultrasound more readily and were less angle dependent than premolars (p-value < 0.001). B-mode ultrasound imaging was then investigated to measure intact enamel in human teeth and validated with μ-computed tomography (μ-CT). Two systems were evaluated for this purpose; the first was an in-house ultrasound apparatus and the second was a commercial ultrasound scanner, with the data obtained validated with μ-CT. The results showed that the commercial ultrasound scanner was more accurate than the in-house scanner with Bland-Altman 95% limits of agreement of -0.48 to 0.47 mm and -1.21 to 0.87 mm respectively. However, the B-mode images produced were not of sufficient clarity and consequently the accuracy of the enamel thickness measurements was not suitable for monitoring progressive enamel loss. Therefore, the simpler A-mode ultrasound approach was investigated for enamel thickness measurements and validated with histological sections of the same teeth. A study of speed of sound (SOS) variations in enamel was also performed. It was found that A-mode ultrasound was able to measure enamel thickness in vitro with an accuracy of 10% compared to histology and the mean SOS in enamel was 6191 ±199 ms-1. Finally, A-mode ultrasound was assessed in vivo (n = 30) to determine if it could monitor enamel thickness reliably and reproducibly on the labial surface of maxillary central incisors. The results showed that ultrasound was a highly reproducible and reliable technique for monitoring enamel thickness with 95% limits of agreement of -0.04 to 0.05 mm. The results demonstrated for the first time in vivo that A-mode ultrasound had sufficient precision (0.05 mm) to allow it to be used as a direct method for serial assessment of erosive TSL. The preferable site for making ultrasonic measurements was the cervical site (site 1) followed by the mid-buccal site (site 2). Therefore ultrasound is a promising and simple method to monitor early erosive changes in thickness of the enamel layer, especially in vulnerable patients with frequent acidic intake or in patients with gastro-oesophageal reflux disease (GORD)

In vitro enamel thickness measurements with ultrasound

In the work described here, agreement between ultrasound and histologic measurements of enamel thickness in vitro was investigated. Fifteen extracted human premolars were sectioned coronally to produce 30 sections. The enamel thickness of each specimen was measured with a 15-MHz hand-held ultrasound probe and verified with histology. The speed of sound in enamel was established. Bland–Altman analysis, intra-class correlation coefficient and Wilcoxon sign rank test were used to assess agreement. The mean speed of sound in enamel was 6191 ± 199 m s−1. Bland–Altman limits of agreement were −0.16 to 0.18 mm when the speed of sound for each specimen was used, and −0.17 to 0.21 mm when the mean speed of sound was used. Intra-class correlation coefficient agreement was 0.97, and the Wilcoxon sign rank test yielded a p-value of 0.55. Using the speed of sound for each specimen results in more accurate measurement of enamel thickness. Ultrasound measurements were in good agreement with histology, which highlights its potential for monitoring the progressive loss of enamel thickness in erosive tooth surface loss

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030