A COMPARATIVE EVALUVATION OF HERBST APPLIANCE AND THE ADVAN SYNC 2 IN THE TREATMENT OF CLASS II MALOCCLUSION

Background D And Objectives: Treatment of class II malocclusion has been a prime focus of orthodontic investigators for decades. Objectives: To evaluate the effects of Herbst fixed functional appliance in the treatment of class II malocclusion, to evaluate the effects of Advansync 2 fixed functional appliance in the treatment of class II malocclusion, to compare the effects of Herbst and Advansync

Many of the earlier methods for treatment of Class II patients typicallyinvolvedremovablecompliance-basedmodalitiessuchasremovablefunctionalappliancesandintermaxillaryClassIIelastics.Overtime, lackofpatientcomplianceandthedesiretoproducemorepredictableresultsinamoreefficientmannerledtothedevelopmentofn umerousfixedappliances,whichdidnotrequirepatientcomplianceforefficacy.Thereare advantages and disadvantages for each type of appliance and the orthodontist mustchoosethemostappropriatemodalityforeachindividualpatient. 14 Withtheconstantarrivalofnewtechniquesandappliances,orthodontists are now equipped with more options than ever before but have theresponsibility to base their treatment decisions on sound evidence. It is crucial fororthodonticappliancestobethoroughlyinvestigatedtofullyunderstandtheirtrueeffects. Appliances designed to correct Class II malocclusions provide their effectsthrough a combination of skeletal and dentoalveolar changes (McSherry et al., 2000).Understandingthespecificskeletalanddentaleffectsofeachapplianceisvitaltoproperapplianceselectionbasedonindi vidualpatientrequirements AdvanSync TM isafixedappliancedevelopedbyOrmco TM totreatClassIImalocclusions.Theapplianceconsistsofcrownscemente dtopermanentupperandlowerfirstmolarswhichareconnectedbytelescopingrods.TheAdvanSync TM wasdesignedtoallowforsi multaneousfixedorthodonticappliancetreatment,asthecrownsareequippedwith 0.022" x 0.028" slots; this has been claimed to reduce overall treatment times.AdvanSync TM ismeanttoposturethemandibleforward,andthereforecanbeclassifiedas a fixed functional appliance. According to Ormco TM , Advansync TM produces stableorthopedicchangebyskeletaladvancementofthemandible,whileeliminatingtheneedforpatientcompliance. 22 Therefore, the purpose of this study was to evaluatethe skeletal, dentoalveolar and soft tissue effects of the AdvanSync appliance and Herbstappliance in the correction of Class II malocclusions in growing patients and tocomparetheeffectsofHerbstandAdvanSyncfixedfunctionalappliances. To standardize the radiographs, all magnifications were corrected to 0%. Oneinvestigatordrewallthetracingsandmeasurements.Inboththegroupsfixedorthodontic treatment was started only at the end of fixed functional phase. Followingthe active phase of the treatment the fixedfunctional appliance wasremovedonlyafter a minimum of three-month retention period.
The effects of ap p liances wer e me a s u r e dattwointervals 1. T 0 -At the b eginni n g of the tr eatment 2. T 1 -Nine months after appliance delivery The data was collected, coded, and fed in SPSS (IBM Version 23) for statistical anal ysis . The descriptive statistics includ ed mean &standa rd deviation. Inferential statistics included paired tTest&Ind ep end ent t Test for the comparison.

Results:-
The descriptive statistics done using SPSS (IBM SPSS Statistics for Windows, Version22.0, Armonk, NY: IBM Corp. Released 2013) included mean & standard deviation. The inferential statistics included independent t test, and paired t test. Independent t test was used to compare the mean of two unrelated independent groups. Paired t test was used to compare the difference between two sets of values of a parameter from the same subjects. The level of significance was set at 0.05 at 95% Confidence Interval.

Advansync2 Fixed Functional Appliance:
In the patients treated with Advansync2 fixed functional appliances, the mean of the cephalometric readings before and after the treatment were recorded ( 331 ANB, UI -A and UL -EPL values were reduced after nine months of theAdvansync2 fixed functionalappliance delivery. UI -A showed no difference in their mean valuesfrom the beginning of the treatment and nine months after appliance delivery.
P-values were observed to be less than 0.5 for parameters such as SNA, WITZ, CO -A, C0 -GN, ANB and LI -B. Hence, we rejected the null hypothesis and accepted the alternate hypothesis for these parameters. Therefore, for these values the differences from the beginning of the treatment and nine months after appliance delivery were observed to be statistically significant. P-value for SNB, C0 -GO, UI -A, UI -A, LI -B, UL -EPL and FMA was however observed to be greater than 0.5. Hence, we failed to reject the null hypothesis for these parameters. Therefore, for these values the differences from the beginning of the treatment and nine months after appliance delivery were observed to be statistically insignificant.

Herbst Fixed Functional Appliance:
In the patients treated with Herbst fixed functional appliances, the mean of the cephalometric readings before and after the treatment were recorded ( SNB, C0 -GN, UI -A, LI -B and FMA was found to have increased after nine months of theHerbst fixed functional appliance delivery. On the contrary SNA, WITZ, CO -A, ANB, LI -B and UL -EPL were decreased after nine months of theHerbst fixed functional appliance delivery. C0 -GO and UI -A had no difference in their mean valuesfrom the beginning of the treatment and nine months after appliance delivery.
P-values was observed to be less than 0.5 for parameters such as SNA, WITZ, C0-GN, ANB, and LI-B. Hence, we rejected the null hypothesis and accepted the alternate hypothesis for these parameters. Therefore, for these values the differences from the beginning of the treatment and nine months after appliance delivery were observed to be statistically significant.
P-value for SNB, CO -A, C0 -GO, UI -A, UI -A, LI -B, UL -EPL and FMA was however observed to be greater than 0.5. Hence, we failed to reject the null hypothesis for these parameters. Therefore, for these values the differences from the beginning of the treatment and nine months after appliance delivery were observed to be statistically insignificant.

Comparison between Advansync2 and Herbst Fixed Functional appliance:
When readings at the beginning of the treatment were compared between patients who were treated with theAdvanSync fixed functional appliances and Herbst fixed functional appliance (Table 3A,   At the beginning of the treatment, when P-values of the patients who underwent treatment with theAdvansync2 fixed functional appliances and Herbst fixed functional appliances were compared for all the observed factors, Pvalue was observed to be greater than 0.05 for all the observed factors. Hence, we failed to reject the null hypothesis. Therefore, the difference at the beginning of treatment between these appliances was observed to be statistically insignificant. After the nine months of appliance delivery, when P-values of the patients who underwent treatment with theAdvansync2 fixed functional appliances and Herbst fixed functional appliances were compared, patients who underwent treatment with theAdvansync2 fixed functional appliances had better readings of C0 -GN, C0 -GO and UI -A and patients underwent treatment with the Herbst fixed functional appliances had better readings of SNA, SNB, WITZ, CO -A, ANB, UI -A, LI -B (angular, linear), UL -EPL and FMA.
After the nine months of appliance delivery, when P-values of the patients who underwent treatment with theAdvansync2 fixed functional appliances and Herbst fixed functional appliances were compared for all the observed factors, P-value was observed to be greater than 0.05 for all the observed factors except C0 -GO. Hence, we failed to reject the null hypothesis for all the observed factors except C0-GO. Therefore, the difference after nine months of appliance delivery between these appliances was observed to be statistically insignificant except CO-GO which was statistically Significant.

Discussion:-
This was a retrospective cephalometric study looking at the dental, skeletal,and soft tissue treatment impacts of the AdvanSync2appliance and Herbst appliance inthe treatment of skeletal Class II malocclusions. Our outcomes indicated that the 2treatmentmodalitiesdelivered comparativeimpactswithcertainspecialcases.
The maxillary restriction was the major skeletal impact of the AdvanSync2.ThisconcurswithanotherresearchbyAl-Jewairetal.testingtheequivalentappliance. 5 Al-Jewairetal.detailedanoveralldecreaseinSNAof3.3°,areduction in A-Na perp of 3.3 mm, and an increase in maxillary length (Co-A) of 1.8mm (from natural growth). 5 In anotherstudybySanthoshJayachandranetal.,SNA decreased by 2.1°, A-Na perp decreased by 2.0 mm, and Co-A increased by 1.7mm. 1 Inourstudy,SNAdecreasedby4.4°.Inallthethreestudies,overallmandibular and vertical skeletal changes with AdvanSync didn't vary altogether fromthe untreated controls. 3 Maxillary limitation has been shown with the Herbst and theMARA,yettheycanenhancemandibulargrowthtoo. 4 Maxillary dentoalveolar changes with the AdvanSync in our investigationwere like the past examination, with no critical changes contrasted with the untreatedcontrols(exceptforaslightincisorextrusion,undoubtedlybecauseoffixedappliancemechanics) 4 .Mandibularden toalveolarchangeswereadditionallyreliable with the past investigation, with the AdvanSync patients displaying incisorprotrusion and proclination and molar mesialization contrasted with their separatecontrolgroups. 4 However,Al-Jewairetal.revealedhugemandibularmolarextrusion with AdvanSync contrasted with the controls; this was not found in ourexamination. 5 Thismightbecreditedtovarietiesinthefixedappliancemechanics utilized. The noticed dentoalveolar changes with the AdvanSync were predictablegenerallywiththosedetailedininvestigationsincludingtheHerbstandtheMARA. 4,5 Theresults of theinvestigationbyMcNamarashowedthatthepubertalgrowth spurt, in the permanent dentition, is the most good time frame to achieve amore noteworthy amount of mandibular skeletal impacts and a more modest measureofdentalcompensationatthelowerarchasforpre-orpost-topperiods. 15 Treatment with MARA and fixed appliances at a pre -peak development stage hadthe option to promptideal results at the degree of the maxillary skeletal structuresthat gave a more modest amount of sagittal advancement and length when contrastedwith untreated Class II control information. 2 The so-called' headgear-effect' thathas been depicted as a potential impact of the Herbst appliance (Hansen et al. 1991; Pancherz and Hägg, 1985) was found additionally in patients treated with the MARAbefore pubescence. Baccetti et al. found in his study that the pre pubertal phase ofdevelopment in presence of residual sutural action of the maxillary skeletal structurestookintoconsiderationtheidealresultinthemaxilla,consequentlyaffirmingprevious observations in a sample treated with the headgear, fixed appliances, andClass II elastics at the same stage in skeletal maturation. The early treatment groupdemonstrated some huge changes in the vertical parameters with a reduction in theintermaxillary skeletal divergency checked by a lot of decrease in the overbite (− 3.1mm on average when contrasted with controls). 15 Regarding the dentoalveolarlevel, the huge adjustments were situated at the lower arch with proclination of thelowerincisors. The absence of sagittal support because of the loss of the lowersecond deciduous molars, which was regular at some phase of the treatment in pre peakpatients,wasjustsomewhatbalancedbythefixedapplianceandthethick lingualarchconnectingthemolarbands. 15 Thismayhaverepresentedtheextrusionandmesializationofthelowerfirstmolars. Theseimpactsarefundamentally the same as those depicted by Baccetti et al. after the utilization ofClassIIelasticsincombinationwithfixedappliances. 15 A limitation of this retrospective study is that only two time points before thetreatment phase and nine months after functional appliance removal was included.Therefore, the long-term effects could not be investigated. A time point at fixedorthodontic treatment should have been recorded. There are also inherent limitationswith the use of a small data base to compare the effects of Herbst and Advansync2fixedfunctionalappliancesinthe treatmentofclassIImalocclusion.
Unmistakablythevariousapplianceshavedifferenttreatmentimpacts, consequently various indications. As indicated by our study and that of Al-Jewairetal., patients requiring restriction of maxillary growth and proclination and protrusionof mandibular incisors, while keeping up the vertical growth pattern, appear to beunmistakably appropriate for AdvanSync treatment. Thusly, growing patients with askeletal Class IImalocclusionbroughtabout by maxillary prognathism whocanaffordmesializationofthemandibulardentitionaretheprimepossibilityforAdvanSync