Canine Cases Research Articles

Leishmaniasis in Tuscany: investigation of hidden human cases and comparison with canine incidence

Abstract The Mediterranean basin hosts endemic areas for leishmaniasis, mainly attributable to the presence of sand flies. Leishmaniasis has gained importance in Europe due to climate change, globalisation and migration. For at least the last 10 years in Tuscany, Italy, there has been an important discrepancy between official notifications of visceral and cutaneous leishmaniasis cases in humans and the number of hospital admissions, highlighting an important underestimation, despite mandatory notification. Moreover, official reports have increased alarmingly in the last three years. Human leishmaniasis does not always require hospitalisation: it often presents cutaneous manifestations, whereas in the immunocompetent individual it may not occur at all. For this reason, it is reasonable to assume that the number of cases is higher than the number of hospitalisations. The project aims to investigate the underreporting of human leishmaniasis cases from 2014 to 2023 by analysing laboratory diagnoses (considering any laboratory test that, according to the Italian Ministry of Health guidelines, is useful to identify a ‘confirmed case’, thus serological tests; parasitological tests; culture tests; PCR). To estimate the extent of underreporting, the capture-recapture method will be used, taking into account laboratory data, official reports and hospital data. Subsequently, a comparison will be made with the incidence, in the same territory, of veterinary cases, particularly in dogs, using data obtained from the Lazio-Tuscany Zooprophylactic Institute, to compare the trend of human and canine cases over time. Analyses are in progress and the results will be presented at the conference. Poor surveillance leads to ineffective prevention policies. The impact of the project is to strengthen the leishmaniasis surveillance system in Tuscany in order to reinforce prevention systems and face emergencies. Key messages • Due to climate change, globalization, and migration, there has been an increase in diagnoses of vector-borne diseases, including Leishmaniasis. • Leishmaniasis surveillance need to be strengthened in order to enhance prevention systems and address emergencies.

Age at Tumor Diagnosis in 14,636 Canine Cases from the Pathology-Based UNIPI Animal Cancer Registry, Italy: One Size Doesn't Fit All.

Cancer is the most common cause of death in adult dogs. All dogs would benefit from early diagnosis, but there are no specific guidelines regarding the schedule of cancer screening in companion animals. The aim of this study was to retrospectively evaluate the age at diagnosis in Italian oncological canine patients. A total of 14,636 canine histologically confirmed neoplastic cases were coded according to the Vet-ICD-O-canine-1 and stratified by malignancy, sex, neutering status, breed, cephalic index, body size, and tumor type. Differences in age distribution were analyzed and the influence of these variables on the time of first malignancy diagnosis was assessed using an event history analysis model. The median age at diagnosis for benign and malignant tumors was 9 and 10 years, respectively. Intact and purebred dogs were diagnosed earlier, but the median age differed significantly by breed. The earliest age at diagnosis was recorded for lymphomas and mast cell tumors. The model showed an accelerating effect of large size, brachy- and dolichocephaly, and sexual integrity in female dogs on the time of malignancy diagnosis. Our results confirm that a "one-size-fits-all" approach to cancer screening is not accurate in dogs and provide relevant data that may lead to the establishment of breed-based screening schedules.

Survey on Dermatological Disorders of Dogs during 2020-2022 in Rabat, Morocco

Dermatology is an important specialty in veterinary medicine, focusing on the skin and its appendages. Therefore, the present study highlighted the percentage of skin disorders, as well as their associated risk factors, from cases received at the Parasitology-Dermatology clinic of the Hassan II Institute of Agronomy and Veterinary Medicine (IAV Hassan II), Rabat, Morocco for two years. A total of 1561 dogs (1450 dogs were in 28 different pure breeds and 111 dogs were mongrels, 805 males, and 756 females, with an average age of 6.5 years old) were presented at the University Veterinary Teaching Hospital (UVTH) of the IAV Hassan II from the end of October 2020 to the end of May 2022 (including vaccinations) and 125 dogs were assessed and 161 skin diseases were found (a few dogs had more than one skin disease). Dermatological examinations represented an average of 8.00% (125/1561) of all canine cases received at the University Veterinary Teaching Hospital. The most common clinical signs were pruritus, alopecia, erythema, onychogryphosis, and visible ectoparasites. Parasitic dermatoses were the most frequent, representing 44.10% of all dermatological cases, followed by allergic dermatoses (25.47%) and fungal skin infections (19.25%). Bacterial skin infections and dermatological manifestations of endocrine disorders were infrequent, representing 8.70% and 2.48%, respectively of all observed cases. Risk factors contributing to the occurrence of canine skin disorders included age and lifestyle for sarcoptic mange. An apparent predilection for the living environment was observed in the case of canine leishmaniosis, and an apparent predilection for sex regarding otodectic mange was also demonstrated. Similar results were found for the living environment and lifestyle concerning canine atopic dermatitis. Data reported herein fill gaps in knowledge of skin disorders and their associated risk factors in dogs in Morocco, demonstrating the dominance of skin diseases of zoonotic interest, including flea bite allergy dermatitis (FBAD), dermatophytosis, and canine leishmaniosis.

Monte Carlo dosimetric analyses on the use of 90Y-IsoPet intratumoral therapy in canine subjects

Objective. To investigate different dosimetric aspects of 90Y-IsoPet™ intratumoral therapy in canine soft tissue sarcomas, model the spatial spread of the gel post-injection, evaluate absorbed dose to clinical target volumes, and assess dose distributions and treatment efficacy. Approach. Six canine cases treated with 90Y-IsoPet™ for soft tissue sarcoma at the Veterinary Health Center, University of Missouri are analyzed in this retrospective study. The dogs received intratumoral IsoPet™ injections, following a grid pattern to achieve a near-uniform dose distribution in the clinical target volume. Two dosimetry methods were performed retrospectively using the Monte Carlo toolkit OpenTOPAS: imaging-based dosimetry obtained from post-injection PET/CT scans, and stylized phantom-based dosimetry modeled from the planned injection points to the gross tumor volume. For the latter, a Gaussian parameter with variable sigma was introduced to reflect the spatial spread of IsoPet™. The two methods were compared using dose-volume histograms (DVHs) and dose homogeneity, allowing an approximation of the closest sigma for the spatial spread of the gel post-injection. In addition, we compared Monte Carlo-based dosimetry with voxel S-value (VSV)-based dosimetry to investigate the dosimetric differences. Main results. Imaging-based dosimetry showed differences between Monte Carlo and VSV calculations in tumor high-density areas with higher self-absorption. Stylized phantom-based dosimetry indicated a more homogeneous target dose with increasing sigma. The sigma approximation of the 90Y-IsoPet™ post-injection gel spread resulted in a median sigma of approximately 0.44 mm across all cases to reproduce the dose heterogeneity observed in Monte Carlo calculations. Significance. The results indicate that dose modeling based on planned injection points can serve as a first-order approximation for the delivered dose in 90Y-IsoPet™ therapy for canine soft tissue sarcomas. The dosimetry evaluation highlights the non-uniformity of absorbed doses despite the gel spread, emphasizing the importance of considering tumor dose heterogeneity in treatment evaluation. Our findings suggest that using Monte Carlo for dose calculation seems more suitable for this type of tumor where high-density areas might play an important role in dosimetry.

Abdominal aortic malformation in 2 dogs

Aneurysms of the abdominal aorta are only sporadically documented in the veterinary literature. This publication describes 2 canine cases in which abdominal aortic malformation was detected by sonography and confirmed by computed tomography. In one case a histological diagnosis of an aortic aneurysm was possible.One dog showed posterior weakness, in the second dog the aortic aneurysm had been noticed sonographically during a routine examination.In the patient with the proven aortic aneurysm, it may be presumed that a hemodynamically relevant component in consequence to the altered flow profile and occurring turbulence exists. In accordance with human medical standards, regular monitoring of these patients, both clinically and by ultrasound, would therefore appear to be useful in order to be able to detect the occurrence or progression of secondary hemodynamic changes and possible thrombus formation at an early stage. In contrast, the second case presented here has not shown any clinical signs with regard to the abdominal vascular malformation up to the present time.

Preoperative parameters (signalment, digital radiography, urinalysis, urine microbiological culture) and novel algorithm improve prediction of canine urocystolith composition.

To determine the accuracy of 4 preoperative parameters (signalment, urinalysis, urine microbiological culture, and digital radiography) in predicting urocystolith composition, compare accuracy between evaluators of varying clinical experience and a mobile application, and propose a novel algorithm to improve accuracy. 175 client-owned dogs with quantitative analyses of urocystoliths between January 1, 2012, and July 31, 2020. Prospective experimental study. Canine urocystolith cases were randomly presented to 6 blinded "stone evaluators" (rotating interns, radiologists, internists) in 3 rounds, each separated by 2 weeks: case data alone, case data with a urolith teaching lecture, and case data with a novel algorithm. Case data were also entered into the Minnesota Urolith Center mobile application. Prediction accuracy was determined by comparison to quantitative laboratory stone analysis results. Prediction accuracy of evaluators varied with experience when shown case data alone (accuracy, 57% to 82%) but improved with a teaching lecture (accuracy, 76% to 89%) and further improved with a novel algorithm (accuracy, 93% to 96%). Mixed stone compositions were the most incorrectly predicted type. Mobile application accuracy was 74%. Use of the 4 preoperative parameters resulted in variable accuracy of urocystolith composition predictions among evaluators. The proposed novel algorithm improves accuracy for all clinicians, surpassing accuracy of the mobile application, and may help guide patient management.

Ecology and molecular analysis of sand flies in Bambuí, Minas Gerais, Brazil: Implications for leishmaniasis surveillance.

Leishmaniasis stands out as a public health problem in the state of Minas Gerais, Brazil, especially in the Midwest region. However, the entomological aspects in several municipalities remain unknown. Therefore, this study aimed to investigate the sand fly fauna in Bambuí, encompassing ecological dynamics and molecular detection of Leishmania. Monthly collections were conducted using CDC light traps from September 2018 to August 2020 across 16 selected points with urban and rural characteristics, chosen based on the coverage area of the Municipal Health Department and the occurrence of canine and human visceral leishmaniasis (VL) cases. Ecological indices of the sand fly population (Chao1, Shannon, Simpson and Pielou) were assessed, and sand fly abundance was correlated to climatic variables (humidity, temperature and rainfall). A total of 8838 specimens representing 17 species within nine genera were collected (estimated species richness by Chao 1 estimator = 17; SE ± 1.8). Predominantly, Lutzomyia longipalpis, Nyssomyia whitmani and Evandromyia cortelezzii constituted approximately 98% of all captured sand flies. While species richness and diversity displayed variations throughout the study, a positive correlation emerged between temperature (p < 0.0001; r = 0.7767), monthly rainfall (p < 0.0001; r = 0.7810) and sand fly abundance. Molecular analysis revealed Leishmania DNA in 2.05% of female sand flies, with the presence of Leishmania infantum in Lu. longipalpis and both Le. infantum and Leishmania braziliensis in Ev. cortelezzii. The entomological data, coupled with the occurrence of autochthonous cases of canine visceral leishmaniasis, offer valuable insights for evidence-based strategies to prevent leishmaniasis in Bambuí.

Human Case of Leptospirosis During a Canine Disease Outbreak - Wyoming, 2023.

Leptospirosis is a zoonotic bacterial disease spread through the urine of infected animals; the typical incubation period is 5-14 days. In approximately 90% of human cases, illness is asymptomatic or mild, characterized by fever, chills, myalgia, nausea, vomiting, diarrhea, headache, calf pain, and conjunctival suffusion, but severe illness can progress to multiorgan dysfunction and death. Although Wyoming is considered a low-risk area for leptospirosis because of its cold and semiarid climate, the Wyoming Department of Health was notified of a probable human case in August 2023, the first reported in the state since 1983. The patient had occupational exposure to dogs but did not report other risk factors. The same week that the human patient's illness began, public health authorities received notification of an increase in canine leptospirosis cases. Public health authorities investigated to determine potential sources of infection, identify additional cases, and recommend control measures. After public health outreach activities were implemented, canine vaccination practices changed substantially in the affected city: a survey conducted after the outbreak revealed that all responding veterinary clinics in the affected city were recommending the vaccine more frequently to dog owners and reporting higher levels of owner compliance with vaccination recommendations. Increased vaccination coverage offers protection from leptospirosis for both dogs and persons exposed to them. Leptospirosis should be considered in the differential diagnosis of persons with occupational exposure to animals and clinically compatible signs and symptoms, including fever, chills, myalgia, nausea, vomiting, diarrhea, headache, calf pain, and conjunctival suffusion, irrespective of geographic location.

Diagnostic ultrasonography and antimicrobial resistance of different pathogens associated with canine and feline lower urinary tract disorders

There is a significant issue concerning the dissemination of antimicrobial-resistant bacteria within companion animals. Urinary tract infections (UTIs) are a common problem in veterinary medicine for which empirical antibiotics are utilized. This study aimed to investigate the antimicrobial resistance of different uropathogens associated with UTIs in canine and feline cases. A total of 146 dogs and 162 cats suffered from lower urinary tract disorders were subjected to ultrasonographic and microbiological examination. Cystitis, urinary sediment, and cystic calculi are the most common ultrasonographic abnormalities associated with bacterial UTIs. Bacterial UTIs were obtained in 36.98 % and 25.92 % of cases in dogs and cats, respectively. A low rate of mixed infection was detected in canine cases (3.7 %). E. coli was the most prevalent pathogen isolated from 46.4 % and 66.7 % of canine and feline isolates, respectively followed by Proteus spp. in canine isolates (16.1 %) and Klebsiella spp. in feline isolates (14.3 %). Staphylococcus spp. was isolated from canine cases only with the detection of methicillin-resistant Staphylococcus pseudintermedius (MRSP) strains at 3.6 %. The majority of the isolated strains were resistant to various antibiotic classes, particularly β-lactams. All gram-negative bacteria were susceptible to amikacin, whereas gram-positive strains exhibited 100 % sensitivity to nitrofurantoin and linezolid. Different bacterial species displayed low resistance to carbapenems and fluoroquinolones. Multi-drug resistance was reported in canine and feline strains at 64.3 % and 54.8 %, respectively. These findings prove the crucial necessity to restrict antibiotic consumption depending on urine culture and antibiotic sensitivity tests.

Canine Leishmaniasis in Algeria: a retrospective study

ABSTRACT The main objectives of our study were to highlight the annual incidence of Canine Leishmaniasis (CanL) in Algeria. A retrospective study was conducted on CanL in Algeria between 2010–2019, by means of a questionnaire survey of 30 canine veterinarians practising in the North central region, Algiers. The retrospective study showed 78 cases of Canine Leishmaniasis (2010 and 2019), with an average of 13.73 per year. The highest mean was observed in 2013:3.400, [1.517–5.283] 95%, with a significant difference (p = 0.028). The cross-sectional survey showed that 44.4% of canine leishmaniasis cases are prevalent in spring and summer. Weight loss was the most frequent clinical sign of 88.9% and skin sampling was the most used diagnostic test to confirm this disease 66.9%. Our study provides a general view of the situation of this disease, particularly the number of cases, and their geographical distribution in Algeria. Canine leishmaniasis (CanL) is a serious zoonosis. Strict measures must be put in place.

Status on the incidence of coronaviral infection (CCoV) in canine cases of haemorrhagic gastroenteritis by rapid lateral flow assay (LFA) in Namakkal

Status on the incidence of coronaviral infection (CCoV) in canine cases of haemorrhagic gastroenteritis by rapid lateral flow assay (LFA) in Namakkal

VG111: A novel formulation demonstrating clinical evidence of anti-pathogenic activity and accelerated wound healing in humans and companion animals

Objectives: The increasing incidence of chronic wounds such as diabetic foot ulcers and pressure ulcers, often compounded by bacterial infections and biofilm formation, presents significant challenges in wound management. Despite advancements in wound care products and a better understanding of molecular wound repair mechanisms, the treatment of chronic ulcerating conditions remains incomplete. VG111, a novel natural product formulation, emerges as a promising therapeutic candidate addressing the need for an effective wound healing agent with antimicrobial and tissue regenerative properties. Materials and Methods: A thorough evaluation of VG111 included antimicrobial assays to determine its minimum inhibitory concentration against an array of pathogens, assessment of its biofilm disruption capabilities, investigation into its profibrogenic activity through scratch assays, and analysis of its immunomodulatory effects on macrophage-derived cytokines. Quality consistency was ensured by high-performance liquid chromatography fingerprinting, while clinical applicability was assessed through observations in canine and human wound healing cases. Statistical Analysis: The cytotoxic effects of VG111 were assessed using a Two-way ANOVA, indicating no significant cytotoxicity at the tested concentration (Column factor p&lt;0.0001). Results: VG111 demonstrated potent antimicrobial action with effective concentrations ranging from 2.5% to 5.0% v/v, targeting resistant strains of Methicillin-resistant Staphylococcus aureus, colistin-resistant Escherichia coli, Acinetobacter baumannii, and other priority pathogens. It showed biofilm clearance, enhanced fibroblast migration, and a favorable immunomodulatory profile by reducing inflammatory cytokines in vitro. In vivo applications corroborated these findings, with significant wound healing observed in both veterinary and clinical settings, negating the need for additional antibiotics. Conclusions: The study emphasized on VG111 as a robust wound healing agent with significant antimicrobial and biofilm-disrupting properties. Its broad-spectrum efficacy against critical pathogens and ability to promote tissue regeneration mark it as a promising avenue in the management of complex chronic wounds, meriting further clinical exploration.

Molecular detection of major coagulase positive Staphylococcus isolates from the canine pyoderma cases

Molecular detection of major coagulase positive Staphylococcus isolates from the canine pyoderma cases

Antimicrobials administration, treatment outcome and bacterial susceptibility in canine pyometra cases subjected to ovariohysterectomy

Pyometra is a bacterial uterine infection that frequently affects intact older bitches. The treatment of choice is ovariohysterectomy, often associated with perioperative antimicrobial therapy. The aim of this retrospective investigation was to evaluate the antibiotic choice at different administration times (pre-surgery, at surgery/during hospitalization, and post-surgery) against complications and outcomes, considering the susceptibility profile of bacteria.The medical records of 51 bitches referred to the Veterinary Teaching Hospital of the University of Turin (January 2021-November 2023) and subjected to ovariohysterectomy and bacteriological examination (bacterial culture and susceptibility tests) of the uterine exudate, were analysed. All animals had a positive outcome without surgical site infections, with a longer hospitalization time in case of peritonitis or sepsis; antimicrobials were administered for an average of 7 days. Comparing the susceptibility of the isolated bacteria towards the antimicrobials administered before, during and after surgery, complete efficacy was observed in 42 %, 46 % and 50 % of cases, respectively. In addition, 5/16 peritonitis cases were treated with an in vitro ineffective antimicrobial, and 30 % of the bitches never received a fully effective antibiotic, according to susceptibility tests using the minimum inhibitory concentration method (MIC). Cephazolin resulted the best option for Escherichia coli, the most frequently isolated bacterium. Our study confirms that pyometra has a good prognosis following ovariohysterectomy and antibiotic administration. Monitoring the clinical evolution without changing the antibiotic according to bacterial susceptibility could represent the right choice in uncomplicated cases. Evaluation of outcomes without postoperative antibacterial treatment or with a shorter course would be another topic worth investigating, with the aim to judiciously reduce the use of antibiotics.

Are Pathogenic Leptospira Species Ubiquitous in Urban Recreational Parks in Sydney, Australia?

Leptospirosis is a zoonotic disease caused by the spirochete bacteria Leptospira spp. From December 2017 to December 2023, a total of 34 canine leptospirosis cases were reported in urban Sydney, Australia. During the same spatio-temporal frame, one locally acquired human case was also reported. As it was hypothesised that human residents and companion dogs might both be exposed to pathogenic Leptospira in community green spaces in Sydney, an environmental survey was conducted from December 2023 to January 2024 to detect the presence of pathogenic Leptospira DNA in multipurpose, recreational public parks in the council areas of the Inner West and City of Sydney, Australia. A total of 75 environmental samples were collected from 20 public parks that were easily accessible by human and canine visitors. Quantitative PCR (qPCR) testing targeting pathogenic and intermediate Leptospira spp. was performed, and differences in detection of Leptospira spp. between dog-allowed and dog-prohibited areas were statistically examined. The global Moran's Index was calculated to identify any spatial autocorrelation in the qPCR results. Pathogenic leptospires were detected in all 20 parks, either in water or soil samples (35/75 samples). Cycle threshold (Ct) values were slightly lower for water samples (Ct 28.52-39.10) compared to soil samples (Ct 33.78-39.77). The chi-squared test and Fisher's exact test results were statistically non-significant (p > 0.05 for both water and soil samples), and there was no spatial autocorrelation detected in the qPCR results (p > 0.05 for both sample types). Although further research is now required, our preliminary results indicate the presence of pathogenic Leptospira DNA and its potential ubiquity in recreational parks in Sydney.

Haematological, biochemical, histopathological studies and isolation of bacteriological agents from canine pyoderma cases in Karnataka

Haematological, biochemical, histopathological studies and isolation of bacteriological agents from canine pyoderma cases in Karnataka

Management of Unilateral Impacted Maxillary Permanent Canine: A Case Report

Introduction The management of maxillary canine is very complex because it must be carefully planned and carried out as a team. The handling of impacted canine cases must be seen from a clinical and radiological point of view. Maxillary canine impaction can be caused by a lack of space or inadequate seed placement. The time to treat canine impaction is usually between the ages of 11 and 14. Objective The aim of this case report was to describe the management of an impacted maxillary left canine of a teenage girl. Successful treatment requires complete diagnostics, such as radiographs, good teamwork, and precise treatment planning of the dental team. Case Report An 11-year-old female patient with class I molar relationship, bimaxillary protrusive, and impacted left upper canine visited the clinic for orthodontic treatment. Extraction of four first premolars (bicuspids) was carried out, and exposure by the periodontist was completed on the maxillary left canine for the installation of a traction device (gold chain traction). Conclusion The appropriate timing, treatment plan, and proper surgical exposure preparation in handling this case produced optimal and ideal results.

Exploratory screening for micro-RNA biomarkers in canine multicentric lymphoma.

Lymphoma is one of the most frequent hematopoietic tumors in dogs and shares similar features with human counterparts. MicroRNAs (miRNA, small non-coding RNAs) are pivotal in gene regulation fine tuning and cancer hallmarks are influenced by their aberrant expression. Consequently, miRNA biomarkers may assist predicting therapeutic response and clinical outcome by providing less-invasive novel diagnostics tools. The aim of this study was to detect dysregulated miRNAs in lymphomatous lymph node tissues in comparison to lymph node material or PBMCs from healthy control dogs. Potential significant differences in miRNA expression profiles between four lymphoma entities were evaluated. A customized PCR array was utilized to profile 89 canine target miRNAs. Quantification was performed using qPCR, relative expression was determined by the delta-delta Ct method, and p-values were calculated with student's t-test. In the 14 diffuse large B-cell lymphoma (DLBCL) patients, 28 and 24 different miRNAs were significantly dysregulated compared to lymph node material or PBMCs. Sixteen miRNAs occurred in both control groups, with 12 miRNAs being down- and four miRNAs being upregulated. The six peripheral T-cell lymphoma (PTCL) samples showed 24 and 25 dysregulated miRNAs when compared to the healthy controls. A combined analysis of DLBCL and PTCL samples revealed seven shared and 19 differently expressed miRNAs. Potential biomarkers in T- and B-cell lymphoma could be the miRNA-17/92 cluster and miRNA-181-family together with miRNA-34a and miRNA-150. Diagnostic utility of potential biomarkers must be validated in larger, prospective cohorts of canine lymphoma cases and in higher numbers of physiological patient material.

The construction of canine distal limb models used in teaching sonography identification of vegetal foreign bodies.

Musculoskeletal ultrasonography is a useful tool to identify radiolucent vegetal foreign bodies (VFBs). However, limited ultrasound experience and unfamiliarity with the normal sonographic appearance of anatomical structures can decrease clinician confidence. This study aimed to design a reusable silicone model that can teach VFB identification within the canine distal limb. Four canine hindlimbs were used to design the silicone models, and 12 canine distal forelimbs were constructed. The model was constructed using cadaver bones, barley grass (Avena fatua) seeds, and silicone to mimic the anatomy of the canine distal limb with a grass seed VFB. Limbs were randomly grouped based on grass seed locations: (1) the interdigital webbing, (2) the palmar surface of the canine forelimb immediately proximal to the metacarpal pad, (3) the dorsal surface of the distal limb immediately proximal to the proximal phalange, or (4) no grass seed (control) placed. Each limb was systematically ultrasounded and compared with cadaver limbs and clinical VFB cases. A comparison of ultrasonographic images validated the construction, revealing that the simulation model replicates the anatomical and echotexture characteristics of the normal canine distal limb. Furthermore, these models also have a likeness to clinical canine distal limb VFB cases and can be utilized as a training tool.

Biomechanics of clear aligner therapy: Assessing the influence of tooth position and flat trimline height in translational movements.

The present clear aligner therapy (CAT) research focuses on isolating and reporting the biomechanical performance for three separate teeth, three translational movements and two flat trimlines at different heights. By identifying key patterns, the research seeks to inform the development of improved aligner designs, ultimately enhancing the effectiveness of clinical orthodontic treatments. In an invitro setting using the Orthodontic Force Simulator (OFS), the biomechanical response of 30 aligners was investigated on three different teeth of a straight symmetric maxillary dentition (central incisor, canine and first molar). Each tooth was tested under two flat trimline conditions (trimmed at gingival margin, TL0; extended 2.0 mm below, TL2) and for three types of translational movements (palatal translation, mesial translation and intrusion). Forces and moments were reported at the centre of resistance for each displaced tooth as well as the two neighbouring teeth, evaluating a total of 18 distinct scenarios. Findings indicate significant variability in the biomechanical responses based on tooth location in the arch, trimline height and movement performed. For palatal translations, the palatal force required to perform the movement was observed highest in molar cases, followed by canine and incisor cases, with a notable difference in the distribution of side effects, indicating a strong influence of tooth anatomy and position in the arch. Similarly, in mesial translations and intrusions molars experienced greater forces and moments than the corresponding movements applied on canines and incisors, but uniquely dispersed for each configuration tested. Regarding the shape of the aligner, TL2 consistently showed improved control over orthodontic movements compared to TL0. Neighbouring teeth frequently displayed compensatory reactions up to about half of the intensity observed on the tooth being moved, with notable variations from case to case. This research supports fundamental factors impacting CAT: Characteristic patterns in the direction and intensity of forces and moments are associated with each of the three translational movements tested. Tooth anatomy and arch location significantly influence the biomechanical performance of aligners, with an observed trend for molars to display higher forces and moments over canines and incisors, but distributed differently. The height of a flat trimline, specifically TL2, shows enhanced control over orthodontic movements. Additional findings revealed a compensatory activity of neighbouring teeth, which varies based on tooth region and movement type. It potentially could influence CAT outcomes negatively and merits attention in future investigations. These results support a tailored CAT method that improves aligner design for better force application. This method needs to be used alongside, and confirmed by, clinical knowledge. Future research should extend these findings to a wider range of clinical conditions for greater applicability in the day-to-day orthodontic practice.