/home/opencode/cpanel/stomaeduj_hacked/uploads/Art-3-Tsolaki.pdf ORTHODONTICS www.stomaeduj.com MANDIBULAR INCISOR INCLINATION IN PATIENTS Original Articles WITH CLASS II MALOCCLUSION: COMPARISON OF TREATMENT EFFECTS THROUGH TIME Anastasia Tsolaki1a , Maria Tsami2b , Athina Chatzigianni3c , Moschos A. Papadopoulos3d* 1Health Professions Division, Department of Orthodontics, College of Dental Medicine, Nova Southeastern University, FL, USA 2Private practice, Larissa, Greece 3Department of Orthodontics, School of Health Scieces, Faculty of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece a Postgraduate Student; e-mail: anastasia.tsolaki96@gmail.com; ORCIDiD: https://orcid.org/0009-0005-9856-8140 b Dentist; e-mail: mlilly@hotmail.com; ORCIDiD: https://orcid.org/0009-0001-8481-0128 c Assistant Professor; e-mail: achatzigianni@dent.auth.gr; ORCIDiD: https://orcid.org/0000-0001-7114-689X d Professor and Head; e-mail: mikepap@dent.auth.gr; ORCIDiD: https://orcid.org/0000-0002-7630-7258 ABSTRACT https://doi.org/10.25241/stomaeduj.2022.9(3-4).art.3 Introduction The aim of this study was to evaluate the effect of different treatments on lower incisor (L1) inclination in patients with Class II malocclusion. Methodology 73 patients (39 females, 34 males) with Class II malocclusion were retrospectively collected from the postgraduate orthodontic clinic. All patients were treated at least with multibracket appliance (MBA) and Class II elastics (CLII) alone (control group), or in combination with the removable-functional appliance (RFA), fixed-functional appliance (FFA), or lingual arch (LA). Pre- and post-treatment L1-NB (mm), L1-GoGn (°) and L1-NB (°) values were analyzed. The analysis of the treatment effect in relation to the outcomes and time were done by the Propensity Score Matching (PSM) method using Cox regression and Survival analysis. Results Regarding L1-NB distance, patients treated only with CLII elastics have lower risk of incisor proclination, however, the risk may occur from the beginning of the treatment. FFA, RFA and LA present higher risk of incisor proclination, but this occurs later in time (hazard ratio HR= 0.4 RFA/0.22 FFA and LA). Concerning L1-GoGn angle, all treatments have high risk of proclination. However, RFA reduces the rate of risk (p=0.003) (HR=0.22), while FFA increases the rate of risk (HR=0.35). Conclusion Multibracket orthodontic treatment with CLII elastics alone produces unfavorable labial incisor inclination rapidly. Combination treatment of RFA with CLII elastics delays the occurrence of proclination, while FFA highly increases the risk of proclination. The use of the lingual arch retains the position of the dentition for longer time, however once the lower incisor proclination occurs, it deteriorates fast. KEYWORDS Mandibular Incisor; Inclination; Class II Malocclusion 1. INTRODUCTION is achieved with a variety of extraction and non- extraction approaches, maxillary expansion, use of From the early steps in orthodontic science, the headgears, functional appliances, fixed-functional position and inclination of the lower incisor has appliances, Class II elastics, with or without skeletal been considered essential in diagnosis, treatment anchorage and other [5]. planning and retention. In 1941 Holly Broadbent Systematic reviews (SRs) and meta-analyses (MAs) correlated normal dentofacial growth with incisor in Class II malocclusion patients treated with mandibular plane angle and set the basis for removable functional appliances revealed minor cephalometric analysis [1]. In 1943 Margolis was the skeletal changes, while the effects of the treatment first to correlate lower incisor inclination with chin were mostly dentoalveolar, such as increased position [2]. Tweed advocated that the mandibular inclination of lower incisors and uprighting of the incisors must always be positioned upright on the maxillary incisors [6-7]. Because the lack of success alveolar process in order to achieve harmony in the of functional appliances has been attributed under lower facial third [3]. some circumstances to the lack of patient compliance Class II malocclusion is present in approximately regarding appliance wear, the treatment effects of one-third of the patients seeking orthodontic fixed functional appliances (FFAs) were examined treatment [4]. Correction of Class II discrepancies as well in other SRs or/and MAs and presented with OPEN ACCESS This is an Open Access article under the CC BY-NC 4.0 license. Peer-Reviewed Article Citation: Tsolaki A, Tsami M, Chatzigianni A, Papadopoulos AM. Mandibular incisor inclination in patients with class II malocclusion: comparison of treatment effects through time. Stoma Edu J. 2022;9(3-4):95-102. Received: January 02, 2022; Revised: March 17, 2022; Accepted: March 28, 2022; Published: March 30, 2022. *Corresponding author: Prof. Moschos A. Papadopoulos; Department of Orthodontics, School of Health Sciences, Faculty of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece; Tel./Fax: +302310999556; e-mail: mikepap@dent.auth.gr Copyright: © 2022 the Editorial Council for the Stomatology Edu Journal. Stoma Edu J. 2022;9(3-4):95-102 pISSN 2360-2406; eISSN 2502-0285 95 Tsolaki A, et al. www.stomaeduj.com similar results as far as the inclination of the lower line (L1-GoGn°) and the distance between L1 and Original Articles incisors is concerned. Nasion-B point line (L1-NB mm) were examined. The Further, the application of Class II elastics apart from total treatment time and also the treatment time the side effects that produces, such as extrusion of each appliance was available from the patients’ of the lower first molars and of the upper incisors, records. More specifically, the date of application their use is highly associated with proclination of of the MB, CLII, RFA, FFA or LA and the total active the lower incisors and retroclination of the upper treatment of each appliance were retrieved. Also, incisors [8]. crowding was evident in 35 patients (47,9%), while 38 A direct comparison of the effect of different patients (52,1%) had no crowding (Tab. 2). therapeutic methods on lower incisor inclination Table 2. Descriptive statistics of the sample regarding the presence of seems not to have been examined thoroughly. Thus, crowding in the lower arch in the different treatment groups. the aim of this study was to evaluate the effect of MBA+CLII No other + FFA + RFA + LA Total different orthodontic treatment approaches taking treatment also into consideration the possible influence of treatment time on the lower incisor inclination of Yes 23 3 2 7 35 Crowdin patients presenting Class II discrepancy. No 16 7 15 0 38 Total 39 10 17 7 73 2. METHODOLOGY An analysis of the treatment effect in relation to the A study sample of 73 patients (39 females and 34 outcomes and the implementation of time was done males; mean age 13.2±4.1 years) was retrospectively by the propensity score matching (PSM) method collected in consecutive order from the Postgraduate using Cox regression and Survival analysis [9]. In Orthodontic Clinic. The patients’ inclusion criterion randomized clinical trials (RCTs) treatment groups was the Class II malocclusion with at least half cusp and/or control groups are balanced for the baseline to full Class II canine and molar relationship and Class characteristics of participants between groups with II treatment approach, such as functional appliance, no systematically difference between them. With Class II elastics and other. Patients with extractions, the use of PSM the differences between groups can stripping, surgical intervention or craniofacial be estimated and the distribution of the baseline anomalies were excluded. All patients were treated at characteristics can be balanced to be similar between least with the multibracket appliance (MBA) (Straight the groups [10]. In the orthodontic field, orthodontic wire, Roth prescription) in both dental arches and treatments are not static with a direct treatment Class II elastics, with or without another treatment, effect. Instead, different types of treatments, which preceded or followed, such as removable- appliances or methods are used during a long period functional appliance (RFA), fixed-functional appliance of time and usually there are differences between a (FFA), or lingual arch (LA). specific treatment effect and the time of application The descriptive statistics of the sample are shown of the corresponding treatment. The treatment effect in Tab. 1. Pre-treatment and post-treatment lateral is affected by the time period of the treatment. The cephalograms were analyzed with the use of the involvement of time in the orthodontic treatment Viewbox 4 software (dHal Software, Athens, Greece) effect can be studied and analyzed using two to measure the inclination and position of the lower statistical tools, which are very common in medical incisors at the beginning and at the end of the science; the Survival analysis and the Cox regression treatment. The angles between the lower incisor analysis. Survival analysis is a statistical technique to (L1) and the Nasion-B point line (L1-NB°), the Go-Gn analyze a “time to event outcome variable”, where the Table 1. Descriptive statistics of the sample. CLII Tx time: Time of Class II elastics wear during treatment; Total Tx Time: Total treatment duration; L1-NB (mm): distance between the lower incisor (L1) and Nasion-B point line; L1-GoGn°: angle between L1 and the Nasion-B point line; L1-GoGn°: angle between L1 and the Go-Gn line. Variable N Age Sex CLII Total L1-NB L1-NB L1-GoGN Treatment Mean Male Tx Time Tx Time (mm) (°) (°) (±SD) % Mean Mean Mean Mean Mean (±SD) (±SD) (±SD) (±SD) (±SD) MBA + CLII 39 14.1 46.15% 13 37.6 2.73 25.5 98.3 (±5.18) (±8.2) (±16.3) (±1.58) (±6.44) (±6.40) MBA + CLII + FFA 10 13.8 60% 11 34.4 4 30.8 107 (±1.93) (±10.9) (±8) (±2.43) (±8.36) (±8.44) MBA + CLII + RFA 17 11.4 47.06% 16.4 48.6 3.93 28.3 102 (±1.46) (±10.7) (±16.1) (±2.35) (±6.03) (±5.02) MBA + CLII + LA 7 11.1 71.42% 11.2 47.7 2.70 26.8 99.7 (±1.07) (±13.4) (±19.9) (±1.63) (±8.15) (±9.08) 96 Stoma Edu J. 2022;9(3-4):95-102 pISSN 2360-2406; eISSN 2502-0285 Mandibular incisor inclination in Class II malocclusion www.stomaeduj.com outcome variable are the treatments that have been value. Tab. 3 and Figs. 1, 2, 3 show the results of the Original Articles used in a study and the event is the goal achievement Cox regression analysis. of the treatment. The Cox (Proportional Hazards) Table 3. Prognostic performance of different treatments on the lower regression is a statistical method for studying the incisor inclination for the accepted outcome (post-treatment normal effect of multiple variables upon the time an event incisor inclination) after adjusting with ATT Propensity Score. takes to happen. Treatments/ L1-NB L1-NB L1-GoGN An important limitation of observational studies Outcomes (mm) (°) (°) in relation to non-randomized study designs is the treatment selection bias. Due to that limitation, the Coef -1.15 -1.48 -1.12 baseline characteristics of the study population Hazard could dramatically differ for each treatment group FFA Ratio 0.31 (0.07-1.41) 0.23 (0.02-2.07) 0.32 (0.04-2.46) [10-13]. Direct estimations about the treatment (CI) effect without considering these sources of p value 0. 1312 0.36 0. 276 heterogeneity can lead to bias estimations about Coef -3.39 -2.71 -0.98 the treatment effects [14]. Propensity score can be Hazard estimated by a logistic regression model that predicts RFA Ratio 0.03 (0.003-0.33) 0.07 (0.01-0.31) 0.37 (0.05-2.69) the treatment assignment given the observed (CI) baseline characteristics. This method gives the p value 0.00371** 0.000618*** 0.260 opportunity to evaluate the treatments through relatively homogeneous population groups. It is Coef -1.37 1.77 -1.62 worth mentioning that the considerable amount Hazard of differences in the sample size of the groups of LA Ratio 0.25 (0.05-1.29) 0.17 (0.01-2.88) 0.2 (0.01-3.32) this study is balanced with the use of PSM, which (CI) takes this inequality into account. For example, p value 0.09813 0.22 0.12 crowding differences between patient groups were *p<0.05, **p<0.01 balanced with the use of different statistical weights among groups. Randomized clinical trials are the goal standard for estimating casual effectiveness by assigning treatments independently from covariates. The process of propensity score simulates the process of RCTs with the limitation that the unobserved confounders have no way to be adjusted [15]. 3. RESULTS AFirst the Propensity Score of the 73 patients was computed with the Average Treatment Effect (ATE) method to compare outcomes among the Figure 1. Reverse Kaplan-Meier is presented for the cumulative treatments. Treatment outcomes were categorized probability of Lower Incisor NB (mm) for the endpoint with normal into “accepted” or “not accepted” according to the inclination. value of the outcome and the relationship with the physiological mean values. More specific, the value of outcome is referred to the post-treatment value of the lower incisor inclination. Accepted outcomes had a post-treatment incisor inclination value within the mean ± Standard Deviation (SD) value of each measurement, while not accepted outcomes lay beyond the SD values and exceeded the mean value. The ATE method was also used to compute Propensity Scores for the population and a Cox proportional hazard model was implemented to assess the impact of the treatments on the above outcomes. The group Figure 2. Reverse Kaplan-Meier is presented for the cumulative of patients treated with MBA/Class II elastics and no probability of Lower Incisor-GoGN angle for the endpoint with normal inclination. other treatment were used as reference group to estimate the effect of the other treatments. For the The analysis showed that RFA treatment results in above method we had two groups of patients, those a statistically significant achieve effect of L1-NB who had an accepted outcome (normal lower incisor (mm) and the L1-NB (°) (p=0.00371 and 0.000618 inclination) and those who had a non-accepted respectively). The negative sign of the regression outcome (lower incisor proclination), according to coefficient (coef ) in the tables shows that the the post-treatment incisor inclination value. probability of each additional treatment to reach the desired accepted result for every outcome reduces 3.1 Patients with an accepted outcome the effect of Class II elastics. For example, regarding Patients with an accepted outcome presented an the L1-NB (mm) value, the RFA treatment decreases accepted post-treatment lower incisor inclination the cumulative probability of producing an accepted Stoma Edu J. 2022;9(3-4): 95-102 pISSN 2360-2406; eISSN 2502-0285 97 Tsolaki A, et al. www.stomaeduj.com outcome by a hazard ratio of only 0.03, while the FFA Regarding the L1-GoGn (°) measurement, according Original Articles decreases the probability by 0.31 and the LA by 0.25. to the Kaplan-Meier graph (Fig. 5) patients treated with CLII, RFA, FFA and LA have all high risk of producing lower incisor proclination. Likewise, for CLII alone treatment the risk may occur from the beginning, during the first weeks of application of the Class II elastics. In contrast, RFA, FFA, and LA have the probability to produce the occurrence of proclination later in time than the CLII. Figure 3. Reverse Kaplan-Meier is presented for the cumulative probability of Lower Incisor-NB angle for the endpoint with normal inclination. 3.2 Patients with a non-accepted outcome Patients with a non-accepted outcome presented a non-accepted post-treatment lower incisor Figure 5. Kaplan-Meier curve is presented for patients with Lower inclination value. Further analysis was conducted Incisor-GoGN angle with proclined endpoint. in this group of patients and these were the most important results. Specifically, the Average Treatment Effect on the Treated (ATT) Propensity Score was Especially the RFA treatment reduces the rate of risk computed for the group who exceeded the accepted with a statistical significance of p=0.00269 compared values and presented incisor proclination. Survival to the other treatments, with a hazard ratio of 0.22. analysis was conducted to examine the risk of labial On the other hand, FFA has an increased rate of risk incisor inclination among the different treatments. for proclination with a hazard ratio of 0.35. Regarding the L1-NB (mm) measurement, according Lastly, regarding the L1-NB (°) measurement, to the Kaplan-Meier graph (Fig. 4) patients treated according to the Kaplan-Meier graph (Fig. 6) patients only with CLII have lower risk of exceeding the L1-NB treated with CLII, RFA, FFA and LA have all again high (mm) value. risk of producing lower incisor proclination. Figure 4. Kaplan-Meier curve is presented for patients with Lower Incisor-NB (mm) for the proclined endpoint. Figure 6. Kaplan-Meier curve is presented for patients with Lower Incisor-NB angle with proclined endpoint. The risk for labial inclination is the same as for L1- However, this risk may occur from the beginning, GoGn (°) measurement. RFA reduces the rate of risk during the first weeks of application of the Class II with a statistical significance of p=0.0465 compared elastics. On the other hand, RFA, FFA, and LA present to the other treatments, with a hazard ratio of 0.3. a higher risk of producing a not accepted outcome FFA on the other hand has an increased rate of risk of the L1-NB (mm) value compared to CLII alone for increasing lower incisor inclination with a hazard during the treatment, but this happens later in time ratio of 0.5. than the CLII. Moreover, RFA causes a not accepted As above, only the combination of CLII with FFA L1-NB (mm) value in a later time compared to all the increases the probability of proclination, while the other treatments. combination with RFA and LA seems to reduce the Specifically, RFA has a higher rate of increasing the probability of lower incisor proclination with a probability of risk of proclination. hazard ratio of 0.4 compared to FFA and LA, which As for the treatment time, CLII alone produces have a hazard ratio of 0.22. This means that once unfavorable treatment effects more rapidly the risk occurs, RFA can deteriorate the L1-NB (mm) compared to all combinations. Table 4 shows the value in a shorter time period. effect sizes of survival analysis. 98 Stoma Edu J. 2022;9(3-4):95-102 pISSN 2360-2406; eISSN 2502-0285 Mandibular incisor inclination in Class II malocclusion www.stomaeduj.com Class II elastics are effective in correcting class II Original Articles Table 4. Prognostic performance of treatments for L1-NB (mm), L1-NB (°), L1-GoGN (°) for the not accepted outcome (post-treatment lower incisor malocclusions and that their effects are primarily proclination) after adjusting with ATT Propensity Score. dentoalveolar, such as flaring of mandibular incisors Treatments/ L1-NB L1-NB L1-GoGN and loss of mandibular anchorage. In this study it Outcomes (mm) (°) (°) was evident that multibracket appliance with Class II Coef -1.5 -0.68 -1.06 elastics treatment is associated with the highest risk Hazard of lower incisor proclination compared to the other FFA Ratio 0.22 (0.03-1.61) 0.5 (0.12-2.17) 0.35 (0.08-1.5) treatments under investigation. (CI) To overcome the lower incisor proclination side effect, p value 0.137 0.36 0.157 different types of appliances have been proposed to reinforce the anchorage in the molar region and Coef -0.9 -1.2 -1.51 thus, overcome the mandibular dental side effects. Hazard For example, the development of the lingual arch RFA Ratio 0.4 (0.06-2.52) 0.3 (0.09 - 0.98) 0.22 (0.08-0.59) is attributed to the efforts of Lloyd S. Lourie [25] (CI) and John V. Mershon [26]. It is considered that the p value 0.333 0.0465 0.00269** lingual arch can resolve lower incisor crowding by Coef -1.5 0.87 -1.08 maintaining the arch perimeter [27]. The aim of Hazard including the lingual arch in the treatment of Class LA Ratio 0.22 (0.02-3.12) 0.42 (0.11-1.56) 0.34 (0.09-1.33) II malocclusion is mostly to enhance mandibular (CI) anchorage and minimize the side effects of Class II p value 0.265 0.19 0.12 elastics, such as molar rotation and lingual tipping *p<0.05, **p<0.01 and protrusion of mandibular incisors [28]. In this study it was confirmed that the use of the lingual 3.3 Treatment time arch, when used with MBA and Class II elastics can It is worth mentioning that the treatment time of retain the mandibular incisors for a longer period the CLII elastics wear was studied separately for of time compared to MBA and Class II elastics each combination treatment, so as to determine alone. This means that the lingual arch retains whether the treatment time of the CLII elastics in the the probability of risk for a longer period of time, combined treatments with other appliances affects the final outcome. After the statistical analysis it meaning that the lower incisors may remain stable appeared that the treatment time of CLII elastics during treatment before reaching the not accepted in the combination treatments does not affect proclined endpoint. However, once the risk with the statistically significant the outcome (p-values of use of LA occurs, then the incisors may deteriorate 0.765, 0.907, 0.498 for lower incisor NB, lower incisor fast. Concluding, there is a timepoint after which the NB (mm) and lower incisor GoGn respectively). lower incisor inclination may deteriorate very fast and abruptly when lingual arch and Class II elastics 4. DISCUSSION are used. A lot of studies have been conducted in order TAs already known, studies comparing dentoskeletal to evaluate the skeletal and dental changes that alterations in treated Class II patients with those account for the Class II correction in subjects treated of untreated subjects, revealed significant with Class II elastics compared with subjects treated retroclination of maxillary incisors and protrusion with removable or fixed functional appliances [29- and proclination of lower incisors [16-18]. 31]. These studies suggested that either there was Despite the limitation of this study regarding the no statistically significant difference between the considerable amount of differences in the sample two treatment modalities or if there was any, it did size of the groups, the use of the PSM method, not last in the long term [32]. These results indicate which takes into account those differences, seemed that the final outcome of the treatment of Class II to have clearly depicted the probability of risk for malocclusion might be similar independently of the lower incisor proclination between the investigated orthodontic device used. treatment approaches. However, the risks of incisor proclination varied The use of intermaxillary elastics is well documented among treatments at this study. Compared to the in the literature, which claims that they are effective use of MB and CLII alone, only the combination of MB in correcting the anteroposterior relationship of the and CLII with FFA increases the probability of incisor dentition, although undesirable side effects can proclination, while the combination of MB and CLII occur [19-22]. Most authors mention adverse results with RFA or LA seems to reduce the probability of from the horizontal vector of force, which has been risk of proclination. This probably means that the use shown to rotate or mesially tip the mandibular first of RFA reduces the total time of Class II elastics wear, molars, procline the mandibular anterior teeth, leading to more favorable results. and displace the entire lower dental arch anteriorly Systematic reviews and meta-analysis concluded [19,21,23,24]. Systematic reviews revealed that that the treatment of Class II malocclusion with FFAs Stoma Edu J. 2022;9(3-4):95-102 pISSN 2360-2406; eISSN 2502-0285 99 Tsolaki A, et al. www.stomaeduj.com was associated with more pronounced soft tissue 6. ABBREVIATIONS Original Articles and dentoalveolar changes, including significant proclination and protrusion of mandibular incisors CLII: Class II elastics [16]. RFA: Removable functional appliance This is in accordance with our study and moreover, it FFA: Fixed functional appliance was evident that FFA treatment has the highest risk LA: Lingual arch of producing mandibular incisor proclination among MBA: Multibracket appliance HR: Hazard ratio all treatments under investigation. PSM: Propensity score matching RCT: Randomized clinical trial 5. CONCLUSION Tx: Treatment ATE: Average treatment effect Multibracket appliance (MBA) orthodontic treatment SD: Standard deviation with Class II elastics alone is associated with the high risk of producing unfavorable mandibular CONFLICT OF INTEREST incisor proclination, which takes place more rapidly None to declare. when compared to the combination treatment of Class II elastics with the other appliances under FUNDING investigation. This research did not receive any specific grant from funding Removable appliance treatment in combination agencies in the public, commercial, or not-for-profit sectors.. with MBA and Class II elastics reduces the risk and AUTHOR CONTRIBUTIONS delays the occurrence of proclination, AT, MT: Data collection and interpretation, manuscript writing; AC: • Fixed functional appliance treatment in combina- Conceptualization, methodology, manuscript writing, reviewing tion with MBA and Class II elastics highly increases and editing; MAP: Conceptualization, methodology, supervision, the risk of proclination. reviewing and editing. • The use of the lingual arch in combination with MBA and Class II elastics retains the probability of risk at AKNOWLEDGEMENTS the early stages of treatment, however a high risk of The authors acknowledge Mr. Evaggelos Akrivos for the statistical incisor proclination occurs abruptly later in time. analysis of the data. REFERENCES 1. Broadbent BH. 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Google Scholar CrossRef Google Scholar Scopus Anastasia TSOLAKI DDS, Postgraduate Student Health Professions Division Department of Orthodontics College of Dental Medicine Nova Southeastern University, FL, USA CV Anastasia Tsolaki, DDS, is a postgraduate student in Orthodontics at the Department of Orthodontics, College of Dental Medicine, Health Professions Division, Nova Southwestern University in Florida, USA since 2021. She received her Doctor of Dental Surgery degree from the Aristotle University of Thessaloniki, Greece in 2019. She has participated in a number of congresses and conferences in the dental and orthodontic field with poster or oral presentation. She has professional experience in dental and orthodontic practices since 2020. Her skills include knowledge of 3 foreign languages. Stoma Edu J. 2022;9(3-4):95-102 pISSN 2360-2406; eISSN 2502-0285 101 Tsolaki A, et al. www.stomaeduj.com Questions Original Articles 1. There is a higher risk of mandibular incisor proclination when: qa. Fixed functional appliances are combined with multibracket appliance treatment; qb. Removable appliances are combined with multibracket treatment and Class II elastics; qc. Removable appliance alone are used; qd. Lingual arch is used. 2. Which appliance retains the inclination of the lower incisors at the early stages of treatment? qa. The multibracket appliance; qb. The fixed functional appliance; qc. The removable appliance; qd. The lingual arch. 3. When does the risk of mandibular incisor proclination increase during treatment? qa. At the early stages of multibracket appliance treatment; qb. At the later stages of multibracket and Class II treatment, where lingual arch is used; qc. At the early stages of treatment, where lingual arch is used; qd. At the early stages of fixed functional treatment. 4. Which combination treatment delays the occurrence of lower incisor proclination? qa. The combination of fixed functional appliance and multibracket appliance; qb. The combination of Class II elastics with multibracket appliance; qc. The combination of removable appliance, followed by multibracket appliance and Class II elastics; qd. The combination of fixed functional appliance, multibracket appliance and Class II elastics. https://iccmo.org/home/event/india-2023 102 Stoma Edu J. 2022;9(3-4):95-102 pISSN 2360-2406; eISSN 2502-0285