Y HQC VIET NAM THANG 5 - SO DAC BIET/2012
LAM SANG VA KET QUA DIEU TRj SAI KHOP CAN LOAI I
THEO ANGLE B A N G KHI CU DAY THANG
TOM T A T
Qua phan tich cac dac diem lam sang va danh gia ket qua dieu tri sai khdp can loai I theo Angle bSng khi cu day thang cho 127 benh nhan bSng phu'dng phap nghien cu'u theo chieu dpc, chung tdi rut ra mpt so ket luan sau;
- Trong sai khdp can loai I theo Angle, cac tru'dng hpp sal khdp can tieu loai I theo Anderson chiem ty le cao nhat 50,40%.
- Tren lam sang cac benh nhan sai khdp can loai I theo Angle co cac bieu hien:
. Khudn mat can doi d tu' the nhin thang chiem ty le cao nhat 74,8%.
. Md nha chu va khdp thai du'dng ham binh thu'dng.
Phim Cephalometric cd tu'dng quan tot theo chieu tru'dc sau.
. Diem PAR trung binh cua ca nhdm nghien ciru tru'dc dieu tri la 23,28±7,24 va sau dieu tn la 4,61±1,11.
- Ket qua dieu tri tot chiem ty le 90.55%.
SUMMARY
CLINICAL ANALYSIS AND RESULTS OF APPLYING STRAIGHT WIRE APPLIANCE AT AN ANGLE IN THE TREATMENT FOR CLASS
I MALOCCLUSION Through clinical analysis and evaluation of the outcomes of using straight wire appliance at Angles to treat class I malocclusion for 127 patients by Cohort study method, we've concluded that:
In Class I malocclusion, class I of Dewey Anderson's modification occured most often:
50,40% of all types.
Clinical results of treated class I
* Tru'dng Cao dang Yte Khanh Hoa
Nguyen Th^ Dung*, Vu Hai Phong*
malocclusion patients were:
o 74,8% of the patients showed normal appearance of the front of their faces.
0 Periodontal tissues and temporal mandibular joints were normal.
o Cephalometric films showed a good correlation between anterior and posterior regions.
0 Before treatment, the average PAR score of the patients group was 23,28±7,24 After the treatment, the average PAR score was 4,61 ± 1,11.
The overall effect of this treatment was 90.550%.
I. OATVANOE
Trong nhirng nam gan day, chdt lupng cupc sdng ciia ngudi dan Viet Nam ngay cang cao, do dd nhu cau thlm my dupe nhilu ngudi quan tam, mpt trong nhiing vin dl tham my dupe ddng dao gidi tre va cac bac phu huynh quan tam la chinh hinh rang mat.
Chinh hinh rang mat khdng chi dem lai tham my ve rang va guong mat, ma cdn ca chiic nang an nhai cho moi ca nhan.
Tren the gioi nganh chinh hinh rang mat phat trien da lau, nhung d nude ta nd tuong ddi mdi me, dac biet chinh hinh rang mat bang khi cu co djnh chi mdi phat trien vao thap nien 90 khi cdng nghe vat lieu y hpc phat trien, kien thiic mdi ve sd sd do sp mat dupe phan tich ky, nhd dd cd chan doan chinh xac va lap ke hoach dieu tri cu the cho timg benh nhan dupe dl dang hon.
Chinh hinh rang mat la ITnh vuc chuyen
CHUYEN DE: HQI NGH] KHOA HOC NGANH Y T ^ ' T I N H KHANH HOA - LAN THtf II
mdn sau ciia nganh rang ham mat Viet nam nham nghien ciiu, theo doi su phat trien va tang trudng cita he thdng ham mat de phong ngira va chiia tri cac sai lech cua cac bd phan rang va xuong ham.
Lich sii chinh hinh rang mat da cd khai niem tir thdi Hippocrate (460-370 BC), Ong la ngudi dau tien ghi nhan ve su chen chitc cua rang Celcus (AD 50) lan dau tien dua ra phucmg phap chinh hinh rang mat bang lire co hpc:
"NIU rang siia van tdn tai khi rang vinh vien mpc, rang se bi lech. Khi dd phai nhd rang siia va dimg ngdn tay day moi ngay cho rang vinh vien bj I?ch di chuyen ve diing vi tri".
Thi ky thii 17, Pierre Fauchard (1678- 1761) da nghi ra cac phuong phap co hpc de sap xep rang deu dan, dng la ngudi dau tien cho rang cd the thuc hien su noi rong cung rang theo cliieu ugang, dng dupe xem la cha de ciia nganh nha khoa hi$n dai.
Norman Kinsley (1850- 1890) dua ra muc tieu ciia dieu trj chinh nha la Iam deu rang va mang lai net mat can xiing.
Edward Angle (1890 - 1928) dua ra khai niem khdp can binh thudng dua tren tuong quan rang ham Ion thii nhat nhu la "chia khda khdp can". Muc tieu dieu tri thay ddi tir chi lam diu rang lech lac den thiet lap khdp cdn ly tuong.
William Proffit (1986 - 1993) dua ra muc tieu ciia dieu tri chinh nha hien dai la
"T90 ra tuong quan khop can tdt nhat cd the chSp nhan va khdp can dn dinh" bao gom giam sat, hudng dan, dieu chinh su tang trudng va cau true rang mat, sira chiia nhiing tuong quan sai lech va di tat cau tnic bang each dilu chmh tuong quan giua rang - xuong mat bang each su dung lire de kich thich va doi hudng phat trien 6 phiic hpp sp mat.
Ngay nay dieu tri chinh hinh rang mat theo quan niem "MultidiscipUnary
Orthodontics"- Muc tieu dieu tri chinh hinh rang mat nham mang lai cho benh nhan mpt kit qua tdt vh thkm my chiic nang, khdp cSn dn dinh va siic khde rang mieng tdt. Ket qua chinh hinh rang mat nay cd the dat dupe bang each ket hpp kien thiirc va ky thuat lam sang ciia tat ca cac mdn nha khoa khac nhu phau thuat mieng, nha chu, phuc hinh, Implant... chinh hinh rang mat khong nhung chi lam di chuyen rang ma cdn la mdt mdn khoa hpc, mpt nghe thuat cua nganh nha khoa.
Ap dung nhiing tien bd va thanh tuu cua nganh chinh hinh rang mat trong nude va th^
gidi, chiing tdi chpn de tai: "Lam sdng vd kit qud dieu tri sai khdp cdn loai 1 theo Angle bdng khi cu day thdng" de nghien cuu nhSm cac muc tieu:
1- Khao sat cac d^c diem lam sang, X quang ciia benh nhan lech lac khdp cSn loai I theo Angle.
2- Danh gia ket qua dieu tri cac b$nh nhan lech lac khop can loai I theo Angle, da dupe dieu tri bang khi cu day thang.
II. D d l TUpNG VA PHUONG PHAP NGHIEN CCTU
2.1. Doi tupng: Benh nhan bi lech lac khop can loai I theo Angle.
Tieu chudn chon lua:
Tudi: > 10, dupe chan doan lech lac khop can loai I, ddng y tham gia nghien cim.
Tieu chudn loai trie:
Benh nhan cd cac loai lech lac khdp can khac hay tudi < 10, khdng tu nguyen tham gia nghien ciiu.
2.2. Phuong phdp nghien ciru:
Thiet ki nghien ciru: Cat ngang md ta, tien ciiu.
Ca mdu nghien cuu: 127 benh nhan dupe thu thap tir thang 3/2008-9/2011.
2.3. Thu thap thong tin:
Tat ca benh nhan nghien cihi deu dupe ghi
Y HQC VI$T NAM THANG 5 - SO DAC BIET/2012
lai cac thong tin vao mdu benh an nghien cmi.
Phucmg tien thu thap thong tin:
Gucmg gap, tham tram, thuoc PAR, may anh, thuoc Icep di do.
Phucmg phap thu thap thong tin:
- Kham Iam sang xac dinh Idiop cdn, chup phim Cephalometric, Panorex va phan tich phim, chup 4nh thjng, nghieng, ijy diu do mlu bang thach cao va do cac chi s6.
- Lap ke hoach dieu tri va giai thich cho benh nhan ve ke hoach dilu tri.
Thuc hi|n ke hoach diSu tri: g6m chuan bi benh nhan truoc dilu tri, gin khau va mac cai (kim loai, kim loai tu bupt, da) va
gin cac loai day cung Nikel-Titanium (NiTi), Stainless Steel (SS), loai day tron (mm) 0.14, 0.16, day vuong 0.16x0.16, day chO nhat 0.16x0.22, 0.17x0.25, 0.19x0.25...benh nhan dugc dieu tri qua cac giai doan dung thing true rang, dong cac khoang tr6ng, hoan chinh giai doan cuoi va duy tri.
Thai gian dilu tri: Khoang 24 dSn 30 thang khong kl giai doan duy tri.
2.4. Bdnh gid kh qud:
Can ctr vao cac tieu chuan: chuc nang, tham my, X quang, dilm PAR truoc va sau dieu tri dl danh gia kit qua.
in. KET QuA NGHIEN COU 1- Phan bo benh nhan theo gioi va
Gidi Nam
m
Conq Ty le %
nhom tuoi;
Nhom tuoi 10 - 15 tuoi
28 53 81 63,77
16 - 24 tuoi 6 34 40 31,49
> 2 5 0 6 6 4,72
Cong 34 93 127 100%
Ty le °/o 26,77 73,22 100%
2- B|nh nhSn bi lech lac rang co cha ha>
Gidi
Nam NiJ Conq
Ty le %
me ciing bi lech lac rang:
Bo me CO lech lac R Khonq
13 46 59 46,45
Co 21 47 68 53,54
Cong 34 93 127 100%
Tyle 26,77 73,22 100%
3- Mat b?nh nhan chyp thang tru-frc va sau dieu tri:
M3t chup thang tru'dc dieu tri
Can doi Khonq can doi Conq
Ty le %
Mat chup thang sau dieu tri Can doi
82 31 113 88,97
Khong can dol 13
1 14 11,02
Cong 95 32 127 100%
Ty le % 74,80 25,19 100%
C H U Y S N BE: Hpi NGHI KHOA HOC NGANH Y TfeTiNH KHANH HOA - LAN THlJll 4- M a t benh n h a n chup
l^at chup ngliieng tru'dc dieu tri
I^at niio iviat tiiang Mat 16m Conq
Ty le %
nghieng tru'o'c va sau dieu t r i : Mat chup nqhienq sau dieu tri Mat nho
15 7 2 24 1 8 , 8 9
Mat thanq 75 21 5 101 7 9 , 5 2
M a t lom 2 0 0 2 1,57
Cong 92 28 7 127 100%
Ty le o/o 7 2 , 4 4 2 2 , 0 4 5 , 5 1 100%
5- Phan loai lech lac rang loai I theo Anderson: Trong loai I theo Angle, Anderson chia ra lam 5 tieu loai, tieu loai I chiem ty le cao nhat 50,4%, tieu loai II chiem 15,7%, tieu loai III chiem 13,4%, tieu loai IV chiem 11,8% va tieu loai V chiem 8,7%.
6- T i n h t r a n g n h a chu tru'o'c va sau dieu t r i :
Mo nha chu trudc dieu tri
Conq Tv le %
Binh thudnq Khonq binh thudnq
Mo nha chu sau diieu tri Binh t h u d n g
103 14 117 9 2 , 1 2
Co t o n thu'dng benh Iv
9 1 10 7 , 8 7
Cong 112
15 127 1 0 0 %
Ty le % 8 8 , 1 8 1 1 , 8 1 100%
7- T i n h t r a n g k h d p t h a i du'Ong h a m triroc va sau dieu t r i :
KhdpTDH Tru'dc dieu tri
Binh thudnq Khonq binh thudnq Conq
Ty le %
Khdp TDH sau dieu tri Binh
thu'dng 105
13 118 9 2 , 9 1
Co t o n thu'dng benh Iv
9 0 9 7 , 0 8
Cpng
114 13 127 100%
Ty le % 89,76 10,23 100%
8- T i n h t r a n g d u d n g
OUdng cong Spee trudc dieu tri
Sau Vuii Phanq Conq
Ty le %
cong Spee trudge va sau dieu t r i : DUdnq conq Spee sau dieu tri Sau
6 3 2 11 8 , 6 6
Vira 31 71 7 109 8 5 , 8 2
Phanq 2 5 0 7 5 , 5 1
Cong 39 79 9 127 100%
Tv le % 3 0 , 7 0 6 2 , 2 0 7,08 100%
Duong cong Spee loai vita truoc dilu tri chilm 62,20%, sau dieu tri chiem 85,82% nhung sir khac biet nay khong co y nghTa thong ke vcri X.^ = 7.107, p = 0,130.
Y HOC VigT NAM THANG 5 - SOBAC BIET/2012
9- Chi so PAR phan theo nhom trudc va sau dieu tri: (theo he s6 ciia Anhl Nhdm
1 (5-10) 2 (11-20) 3 (21-30) 4 ( >31)
Cong
Nhdm tru'dc di'eu tri Sd benh nhan
7 28 83 9 127
Ty le % 5.5 22.0 65.4 7.1 100.0
Nhdm sau dieu tri Sd benh nhan
127
Ty le % 100
- Chi so PAR trung binh truoc dieu tri 23,28±7,241, nho nhit la 6 va Ion nhit la 47 nhom 3 (CO tri s6 tit 21-30) chilm ty le cao nhit 65,40%.
- Chi s6 PAR trung binh sau dilu tri: 4,61±1,114, nho nhit la 2 va Idn nhit la 8, nhom 1 (co hi so tir 5-10) chilm ty le tuyet ddi 100%.
Su khac biet giira chi so PAR trung binh trudc va sau dilu tri co y nghTa thing ke vdi J.^= 277.021, p = 0,000.
10- Moi lien quan giiia nhdm chi so PAR tru'dc dieu tri va khoang con thilu d benh nhan:
Nhom b$nh nhan cd chi s6 PARfrung binh ttr 21- 30, phai nhi rang chilm ty le cao nhit 65,35%.
Nhdm chi so PAR trUdc dieu tri
Conq Ty le %
1 2 3 4
(5 - 10) (11-20) (21- 30) 0 31)
Nhd' rSnq Cd nhd' rang
0 0 78
9 87 68,50
Khong nho rang 7 28
5 0 40 31,49
Cpng 7 28 83 9 127 100%
11- Tri so trung Gdc Gdc SNA Gdc SNB Gdc ANB Gdc 1 - 1
binh ciia cac chi so tren phim Tri sd tru'dc dieu tri
83,6941 i 6,4284 80,8963 i 0,3623 3,7206 i 0,2125 117,9657 i 5,3712
Cephalometric:
Tri s d s a u dieu tri 83,2869 i 0,1971 80,4965 i 0,2738 3,1890 i 0,1729 128,1185 ±0,4595
12- Thoi gian ^eu tri trung binh: 22,56 thang ± 3,366 13- Ket qua dieu tri:
PhUdng phap dieu tri
Khi cu day thanq Cd ket hdp khi cu khac Conq
Tv le %
Ket qua dieu tri Tot
101 14 115 90,55
Kha 6 5 11 8,66
Trung binh 0 1 1 0,78
Cpng 107
20 127 100%
Y HOC VigT NAM THANG 5 - SO D^C BIET/2012 IV. BAN LUAN
1- DiSu kien tien quyet trong chinh hinh rang mat: Trong dieu tri chinh hinh rang mat, co 3 dieu kien tien quyet gop phan cho su thanh cong: su hap tac cua benh nhan, ky nang ciia nha Iam sang va co day du diJ lieu thong tin ve benh nhan.
Su hgp tac cua benh nhan tot hau nhu co the dat dugc khi co dong luc manh me va muc tieu ro rang, dieu nay se lam tang dong luc cua benh nhan hgp tac voi bac sT trong suot qua trinh dieu tri.
Se la sai lam khi nghT rang dieu tri bang khi cu day thang khong can ky nang cao nhu khi sii dung cac loai khi cu co djnh khac, vi thuc hi?n ky thuat be day chinh xac rat can thiet de dieu chinh day cung va bac sT dieu tri phai quan sat theo doi dien bien qua trinh dieu tri nham t3ng chat luong cua ket qua dieu tri.
Mot ke hoach dieu tri tot huong den muc tieu ro rang khi nha Iam sang thu thap day du diJ lieu cua benh nhan truoc khi dieu tri va trong qua trinh dieu tri neu co nhimg van de khong mong muon xay ra kip thai chinh siia de cho ket qua cuoi cimg dat muc tieu mong dgi.
Qua 127 truong hgp dugc dieu tri, chiing toi CO 6 truong hgp benh nhan hgp tac chua tot liic dau nen thai gian dilu trj phai keo dai han ke hoach dieu tri mong dgi.
2- Chin dodn vd ki hogch diiu tri:
Trong chinh hinh rang mat, chan doan va kl hoach dieu trj la ca sof can thiet cho su thanh cong cua dieu tri. Can nhan biet chinh xac vi tri cua rang tren mau ham nghien ciiu la di6u can thiet va dugc bo sung bai cac so do cua phim Cephalometric, tien su benh, va kham Iam sang.
Ke hoach dieu tri bao gom viec liet ke cac muc tieu dieu tri cho tung benh nhan.
Khi cu day thang dugc thiet ke cho khap c4n ly tucmg nhung di nhien cung phai tinh tai
cac yeu to anh huong, khi bat dau dieu tri can phai xem kha nang dap ling cua xuang d6i voi su di chuyen ciia rang va viec nong r^ng xucmg ham tren, kha nang tang truong, ti le rang/khoang con thieu, nhimg phat hien bdt thuong, linh trang siic khoe ciia rang va nha chu, khop thai duang ham, kilu dang ciia mo mem, thoi quea dong co va moi truong xa hoi.
Buac tiep theo la phac thao kl hoach cho vi tri va goc cua cac rang truac, ciing nen tinh den nhiing thay doi do tang truong.
Trong viec xac dinh muc tieu t6i uu, ve mat ngoai va tinh on dinh la rdt quan trong, doi khi la cac yeu to d6i Mp. Bdt k^ su bu trii nao de dem lai su thay doi co the chap nhan dugc cua xuang deu co tac dung phu, su gia tang g6c rang ciia giiia ham tren va ham du6i co lien quan den khuynh huong gia tang dp can phii va khap can hang II [2,5,6]. Thay dSi vS chieu dai cung ham va dung thang true rang deu can khoang trong. Khi bilt cac dilu hSn, phan tich can than se mang lai nhan thiic diy du ve nhu cau neo chan nen trongl27 truong hgp, chiing toi co 87/127 (68,50%) trucmg hgp thieu khoang >10mm va phai nh6 rSng de CO khoang cho rang di chuyen va tang dp can phii. Do nghieng true rang nghieng ve phia moi can thay doi de bu trii cho cac kieu xuong khac nhau, neu muon co d6 cin chia phu hgp, bii trii xuong doi hoi bracket viing rang truac phai thay doi torque de bu tni cho hang II, III xuong.
3- Lam deu vd dung thdng trtfc rang:
Ky thuat day thang khi bat dhx sOr dung, day cung dan hoi tren toan bg cimg rang.
Giai doan dieu tri nay rat quan trgng va di nhien cac tac dung phu phai dugc kilm soat dl tranh dugc cac van de nguy hai. Khi cdc rang chen chiic dugc lam diu, phin ham lien quan se tang do dai va do dai co thi tang khi lam thing duong cong Spee [5,6]. Nhihig
Y HQC VigT NAM THANG 5 - SO BAG BIET/2Q12 khoang khong mong mu6n nay co the la
nguyen nhan Iam cho cac rang truoc nghieng nhieu, dan den su khong viing on.
Do nghieng ly tuong ciia bracket rang nanh thucmg Iam cho chop rang nanh di xa.
Mot tac dung phu ciia day cung hoan chinh khi bang ngang qua bracket cua rang nanh dang dugc dung true hay co than rang nghieng xa se lam tang khop can sau. Mac du tac dung phu thii hai it thay tren I ^ sang, do la khi chan rang di xa se lam cho than rang di gin, trir khi buoc nay dugc tinh tai, khoang neo chan cBn thiSt sau nay c6 th6 bi nguy hai.
4- Kiim sodt can chia vd can phA:
Khi gan bracket cho cac rang tru6c ham duoi CO thi c6 su cham khop, can phai sii d\mg mat phang can dh kiem soat dg can phu.
Khi khi c\i c6 dinh dugc gan diing vi tri, do cin phii sS dugc dieu chinh bang each sii dung day cung cung. Trong giai d o ^ som, day cung tron dugc sii dung, sau do la day 1cm hon o h ^ tren va day cong ngugc a ham duoi (day cung chii nhat ciing). D I giam can phii bang each k^o lui khdi rang truac ham tren, diy cung ciing ham tren dugc su dung, tilt di$n va kich cS day dugc chgn phii hop voi vimg chop rang can kiem soat. Dimg thim keo dl tao luc, neo c h ^ co the tren mot ham hay la lien ham. Day phai trugt de dang trong slot v^ tube a vimg rang sau.
5- Ddng khodng, kit thiic vd duy tri:
Khi tuong quan rang ciia diing, thun dugc dimg d l dong cac khoang tr6ng con lai, sii dung day Ion 0.19x0.25 dugc sir dung de torque dugc chSc chan.
Khi cac rang da hoan tdt viec di chuyin, giai doan duy tri vol khi cu thao lap hay co dinh dugc thuc hien d l giiip 6n dinh kit qua.
iTu dilm ciia khi cu day thang la tuong quan ly tuang giiia cac rang cira dugc thiet lap som trong qua trinh dieu trj va dugc duy tri
cho toi liic hoan tat. Dieu nay lam giam thai gian duy tri so voi cac khi cu khac khi tuong quan rang ciia dugc thiet lap At trg trong dilu tri. Cuoi cimg sir thang bang cua khop can va su thay doi ciia chan rang co the dugc nhan hilt d l dam bao voi benh nhan ve tinh trang chiic nang, tham my cao nhat c6 till dat dugc.
V. KET LUAN
Qua phan tich cac dac diem Iam sang va danh gia ket qua dieu tri sai khop can loai I theo Angle bang khi cu day thang cho 127 benh nhan, nit ra mot so ket luan sau:
1- Cac dac diem Iam sang, X quang ciia b$nh nhan lech lac khap can loai I theo Angle: Trong sai khap can loai I theo Angle, cac truong hgp sai khop can tieu loai I theo Anderson chiem ty Ie cao nhat 50,40%, tieu loai II chilm 15,70%, tieu loai III chiem 13,40%, tilu loai IV chilm 11,80% va tilu loai V chilm 8,70%.
Tren Iam sang cac benh nhan sai khap cin lo^i I theo Angle co cac bieu hien:
- Khuon mat can doi a tu the nhin thang chilm ty Ie cao nhit 74,80%.
- Mo nha chu va khop thai duong ham binh thuang.
- Phim Cephalometric co tuong quan tot theo chieu truoc sau.
- Dilm PAR trung binh cua ca nh6m nghien ciiu truoc dieu tri la 23,28±7,24 va s a u d i l u t r i l a 4 , 6 1 ± l , l l .
2- Ket q u a dieu tri tot chiem ty le 90.55%, kha 8,66% va trung binh 0,78%.
TAI LIEU THAM KHAO
1- Bo mdn chinh hinh rang mat, dai hoc Y Duffc T/P Ho Chi Minh, Chinh hinh rang mdt-Kien thirc ca bdn vd dieu tri du phdng.
Nha xuat ban Y hoc, 2004.
CHUYEN BJ: HQI NGHj KHOA HOC NGANH Y Tg TJNH KHANH HOA - LAN THCT II Hoang Dire Thai, Thuc hanh chinh nha cd
dinh - Ky thugt day cung thdng liin tuc (tap 1,2,3), Nha xuat ban Y hgc, 2011.
DSng Kh^c Tham, Khdo sdt tinh trgng khap cdn a ngudi Viit trong do tuoi 17-27.
Luan van thac sT y hoc, trucmg dai hoc Y Dugc T/P Ho Chi Minh 2000.
Graber T.M, Ranarsdall R.L,
Orthodontics current principles and techniques, third edition, 2000, Mosby, Inc.
5- Proffit, WR, Contemporary Orthodontics, fourth edition, 2007, Mosby, Inc.
6- Steven M.H Lee, Course I, Diagnosis and Treatment Plan Cephalometric Analysis Straight Wire Appliances Mixxed Dentition Dianosis and Treatment, 2010.
MOT SO KET QUA BIEU TRI QUA HINH ANH BENH NHAN
BN. Huynh Nguven Anh Thu !^ tuoi cin LIKL \ung R cua. Angle L tieu loai TG dieu tri 18 lliang
BN. Doan T. Lan 16 tuoi, can cheo \un^ R LUT + R MU hen T, Angle I, tieu loai 3+4, TG dieu tn 22 thanti
BN. Ng. H Phuoc 18 tuoi, R cua tren chen chuc va can cheo. Angle I, tilu loai 1 +3, TG dieu trj 24 thang
