Analysis of the treatment of RT2 recessions with a xenogeneic collagen matrix vs. connective tissue graft combined with a coronally advanced flap. A double-blinded randomized clinical trial

RESEARCH Clinical O al In es iga ions (2024) 28:215 h ps://doi.o g/10.1007/s00784-024-05602-9 In oduc ion Gingi al ecessions a e a e y common pa hology in he adul popula ion [1, 2]. The ideal goal o ecession ea men is o achie e comple e oo co e age (CRC) [3] and good aes he ic esul s o su ounding so issues [4]. In e ms o he pe cen age o mean oo co e age (MRC) and CRC, he ea men o choice is he combina ion o a subepi helial connec i e issue g a (CTG) wi h a co onally ad anced lap (CAF) [5–7]. The use o a CTG inc eases gingi al hickness (GT) and achie es long- e m s abil- i y [8] o he gingi al ma gin [6, 9]. Howe e , ob aining a CTG may cause pos ope a i e complica ions [10, 11], hus leading o he de elopmen o di e en al e na i es, such Ga cía-De-La-Fuen e Ana-Ma ía [email p o ec ed] 1 Uni e si y o he Basque Coun y (UPV/EHU), Biscay, Spain 2 Resea ch G oup: GIU21/042. Depa men o S oma ology, Facul y o Medicine and Nu sing, Uni e si y o he Basque Coun y (UPV/EHU), Ba io Sa iena s/n, Biscay, Leioa 48940, Spain 3 Resea ch G oup: GIU21/042. Depa men o Nu se y I. Facul y o Medicine and Nu sing, Uni e si y o he Basque Coun y (UPV/EHU), Biscay, Spain 4 Resea ch G oup: GIU21/042. Depa men o S oma ology, Uni e si y o he Basque Coun y (UPV/EHU), Biscay, Spain Abs ac Objec i es To compa e he clinical e icacy in e ms o mean oo co e age in RT2 ecession ea ed wi h a co onally ad anced lap combined wi h a xenogeneic collagen ma ix e sus a connec i e issue g a . Ma e ials and me hods A o al o 20 pa ien s we e andomized o ecei e one o wo ea men s: co onally ad anced lap + xenogeneic collagen ma ix ( es g oup) and co onally ad anced lap + connec i e issue g a (con ol g oup). Pa ien - ela ed ou comes measu es and p o essional aes he ic assessmen by oo es he ic sco e we e pe o med. A desc ip i e and analy ical s a is ical analysis o he a iables was pe o med. Resul s A 12 mon hs, he mean oo co e age was 56.48% in he es g oup and 69.72% in he con ol g oup (p = 0.048), wi h a 35% and 40% comple e oo co e age in he xenogeneic collagen ma ix and connec i e issue g a , espec i ely. Tes g oup p esen ed less pain (3.65 s. 5.2 VAS uni s) (p = 0.015) and less su gical ime (45 s. 49.15 min) (p = 0.004) han con ol g oup. Conclusion The use o xenogeneic collagen ma ix in RT2 ecessions was e ec i e o ecession educ ion o hose ob ained using au ologous g a s; wi h he ad an age ha he du a ion o su ge y and pa ien mo bidi y dec eased. The e o e, xenoge- neic collagen ma ix in RT2 ecessions could be an al e na i e o au ologous g a s. Clinical ele ance The use o xenogeneic collagen ma ix dec eases he su ge y ime and pa ien mo bidi y bu connec i e issue g a esul s in signi ican ly be e mean oo co e age and comple e oo co e age. Xenogeneic collagen ma ix can be used in he ea men o RT2 gingi al ecessions. S udy egis a ion NCT 03344315. Keywo ds Collagen ma ix · Gingi al ecession · Connec i e issue · Plas ic su ge y p ocedu es · Clinical ial Recei ed: 8 Decembe 2023 / Accep ed: 5 Ma ch 2024 / Published online: 15 Ma ch 2024 © The Au ho (s) 2024 Analysis o he ea men o RT2 ecessions wi h a xenogeneic collagen ma ix s. connec i e issue g a combined wi h a co onally ad anced lap. A double-blinded andomized clinical ial Ruiz-de-Gopegui-PalaciosElena1· Vilo -Fe nándezMi en1· Ga cía-De-La-Fuen eAna-Ma ía2,4· Ma ichala -MendíaXabie 3· Agui e-Zo zanoLuis-An onio2 1 3 Clinical O al In es iga ions (2024) 28:215 as memb anes [12], biological agen s [13], and allog a s [14]. The objec i e o hese he apies was o ind a he apeu- ic al e na i e o he use o CTGs, hus allowing he ea - men o mul iple ecessions in a single session, which can educe su ge y imes, a oid he need o a second su ge y, and imp o e he colo and ex u e o he issues [12–16]. This is especially impo an in pa ien s wi h pe iodon i is and mul iple ecessions wi h in e p oximal a achmen loss whose ea men is mo e complex [17]. The use o a xenogeneic collagen ma ix (CMX) (Geis lich Mucog a ®: Geis lich Pha ma, AG, Wolhusen Swi ze land) has been p oposed as an al e na i e ea men o egene a ion a ound ee h, ob aining p omising esul s in compa ison wi h CAF alone [6, 18, 19] in achie ing g ea e oo co e age and ke a inized issue. These s udies ha e been pe o med in single and mul iple RT1 [20] ecessions wi h di e en ollow-ups and su gical echniques such as CAF o Modi ied Ad anced Co onal Tunneling Ad anced (MCAT) [6, 18, 19]. While he pe cen age o MRC a 12 mon hs wi h MCAT [21, 22] anged om 53.2% [21] o 71% [22] he combina ion o CMX + CAF [8, 15, 23–26] showed be e esul s in oo co e age (76.28% [23] − 94.32% [26]). RT2 [20] ecessions a e e y p e alen in he adul pop- ula ion [6], bu he CRC is no always p edic able [27]. Al hough he e a e clinical s udies in which CRC as well as high pe cen ages o MRC ha e been achie ed [28, 29], i is necessa y o de e mine he p edic abili y o ea men wi h au ologous g a s as well as wi h possible al e na i e he apies [6, 30], such as he CMX. Hence, his mul icen e clinical ial aimed o compa e he clinical e icacy o CMX (Geis lich Mucog a ®: Geis lich Pha ma, AG, Wolhusen Swi ze land) e sus a subepi helial CTG when combined o CAF [31] o he ea men o RT2 ecessions in e ms o pe cen age o MRC. Ma e ials and me hods T ial design This was a andomized, double-blind, mul icen e (2-cen- e ) clinical ial wi h a 12-mon h ollow-up pe iod. The s udy was egis e ed in clinical ials.go (NCT 03344315) and was conduc ed ollowing he Consolida ed S anda ds o Repo ing T ials (CONSORT) guidelines [32]. The s udy was conduc ed ollowing he p inciples o he Decla a ion o Helsinki ( e ised in 2013) and was app o ed by he Eus- kadi E hics Commi ee (CEIC-E) (PI 20,161,008-PS) in Feb ua y 2017. The p ima y aim was o analyze he pe cen age o MRC associa ed wi h he ea men o ecessions wi h CMX ( es g oup) s. CTG (con ol g oup), wi h he null hypo hesis (H0) ha bo h ea men s a e equally e ec i e a 12 mon hs. The seconda y ou comes we e he pe cen age o CRC, he educ ion o ecession (REC ed) measu ed in mm, he gain in ke a inized issue wid h (KTW), he change in GT, pa ien - ela ed ou come measu es (PROMs) ega ding pos - su gical pain, sa is ac ion wi h he ea men and aes he ics pe cei ed by he pa ien , and aes he ics by a blinded clinical moni o (MVF). Pa icipan s Re e ence popula ion All pa icipan s we e ec ui ed om wo p i a e cen e s be ween Ma ch 2017 and May 2019. Pa ien s ecei ed in o ma ion abou he ea men and he ad an ages and dis- ad an ages o pa icipa ing in his s udy. In o med consen was ob ained om all pa icipan s be o e he s a o he s udy. Inclusion c i e ia we e as ollows: (a) pa ien s ≥18 yea s old; (b) pe iodon ally ea ed and heal hy wi h a leas one o mo e RT2 buccal gingi al ecessions in inciso s, canines, and p emola s, loca ed in he same quad an o sex an wi h a minimal dep h o ≥ 2 mm; (c) ull mou h plaque index had o be unde 25% [33]. The exclusion c i e ia we e as ollows: (a) ac i e pe i- odon al disease; (b) subjec s wi h se e e sys emic pa hology who ook o had aken medica ion ha could in e e e wi h he healing o pe iodon al issues du ing he las 6 mon hs. Sample size calcula ion Fo sample size calcula ion, he pe cen age o MRC was conside ed as he p ima y ou come o calcula e he sample size. To p o ide a s a is ical powe o 80%, an α- isk o 5%, and an SD = 14, as p e iously desc ibed in he li e a u e [22], 18 pa ien s would be necessa y. To accoun o an ici- pa ed d opou s, an addi ional 10% was added, esul ing in 20 pa ien s. Randomiza ion To de e mine he ype o g a (CMX o CTG) o be used, he pa ien s we e andomized in blocks o wo ea men s using s a is ical so wa e (IBM SPSS® S a is ics 20.0) (AMGF). The alloca ion was kep hidden by a clinical moni o (AMGF) un il he ime o he in e en ion in opaque en e- lopes ha we e opened immedia ely a e lap ele a ion. 1 3 215 Page 2 o 12 Clinical O al In es iga ions (2024) 28:215 Con ol o s udy bias The clinical examine (MVF) and he bios a is ician (XMM) we e blinded o he ype o ea men (CMX o CTG). The ep oducibili y o he clinical examine (MVF) was de e - mined by e alua ing 4 pa ien s (p esen ing mul iple RT2 ecessions) no ela ed o he s udy, a leas wice, wi h a sepa a ion o a leas 24 h. An in aclass co ela ion coe - icien > 0.85 was conside ed accep able. In e en ion: Su gical p ocedu e All pa ien s ini ially comple ed a plaque con ol p og am, including o al hygiene ins uc ions [34] o co ec hab- i s ela ed o he e iology as well as a p esu gical p ophy- laxis. All he su ge ies we e pe o med by wo expe ienced pe iodon is s (LAAZ and ERGP), being he CAF [31] he echnique chosen in all cases. The da a ela ed o he chai ime, de ined as he du a ion o he su gical p ocedu e (in minu es) om he i s incision o he las su u e was also egis e ed. A e p epa ing he ecipien bed, a CMX (Geis lich Mucog a ®: Geis lich Pha ma, AG, Wolhusen Swi ze land) ( es g oup) o CTG (con ol g oup), which was ob ained using he UPV/EHU echnique [35], was implan ed. Bo h he CMX and he CTG we e su u ed wi h abso bable su u es (E hicon Vic yl® 5/0; Johnson & Johnson); he lap was su u ed wi h Go e-Tex e-PTFE® 5/0 (W.L. Go e & Associ- a es (UK), LTD, Sco land)) Pos ope a i e ca e included a single p esu gical dose o 2 ml o in amuscula be ame hasone (Celes one® C ono- dose®, Sche ing Plough S.A., Spain), amoxicillin 875 mg/ cla ulanic acid 125 mg (Augmen ine®, GlaxoSmi hKline S.A., Spain) e e y 8 h o 7 days, analgesics on demand (25 mg dexke op o en) and inses wi h 0.2% chlo hexidine diglucona e (2 imes a day o 3 weeks). Also, local cold applica ions o wo days, a so die and no physical exe - cise du ing he i s week a e he su ge y we e ad ised. Su u es we e emo ed om he pala e a 7 days and om he ecipien bed a 14 days espec i ely. A 21 days a e su ge y, daily b ushing was esumed [34]. Moni o ing and da a collec ion A 7, 14 days, 4 weeks, 6, and 12 mon hs pa ien s we e scheduled o a end ollow-up appoin men s, which included a p o essional plaque emo al wi h ein o cemen o o al hygiene ins uc ions. Clinical pa ame e s A baseline, 6 and 12 mon hs, an expe ienced, blinded, and p e iously calib a ed examine (MVF) eco ded he ol- lowing pa ame e s using a s anda dized pe iodon al p obe (PCP-11, Hu-F iedy, M g. Co. LLC, Chicago, USA); he measu emen s we e ounded o he nea es 0.5 mm: ●Recession dep h (REC dep h): measu ed in he mid es- ibula om he cemen o-enamel junc ion (CEJ) o he deepes poin o he pocke . As non-ca ious ce ical le- sions we e no excluded, i he CEJ was no p esen o no de ec able, i was de e mined using he echnique desc ibed by Cai o and Pini-P a o [36] in 2010. ●Recession wid h (REC wid h): measu ed mesio-dis ally a he le el o he CEJ. ●Ke a inized issue wid h (KTW): measu ed om he gingi al ma gin o he mucogingi al junc ion. ●Clinical a achmen le el (CAL), measu ed om he CEJ o he gingi al ma gin o he deepes poin o he pocke (PD + REC dep h). ●Pe cen age o CRC ( he numbe o ea ed ecessions wi h REC dep h = 0 mm): CRC × 100/numbe o ecessions. ●Pe cen age o MRC (mean p eope a i e REC dep h -mean pos ope a i e REC dep h/mean p eope a i e REC dep h × 100) we e calcula ed. ●GT: measu ed 3 mm apical om he cen e o he gingi- al ma gin (a baseline and 12 mon hs) using a 25-gauge K endodon ic ile wi h a ubbe s oppe , measu ed pe - pendicula o he oo h axis unde local anes hesia. Pa ien - ela ed ou comes measu es Rega ding es he ics, a PROM was ca ied ou using a isual analogue scale (VAS, anging om 0 o10) in which pa ien s we e asked o sco e hei sa is ac ion ela ed o hei clinical expe ience (p ocedu e and pos ope a i e pain) a 7 days and es he ic (0 = wo s possible aes he ic esul and 10 = excel- len aes he ic esul ) a 12 mon hs. Respec ing he clinical expe ience (0 was conside ed he wo s p ocedu e expe i- enced o he pa ien and 10 he bes ) and o pos ope a i e pain (0 = no pain and 10 = ex eme pain). P o essional es he ic e alua ion Besides he pa ien ’s es he ic pe cep ion, he es he ics we e also assessed om a p o essional poin o iew. Thus, one blinded and calib a ed examine (MVF) compa ed he pho- og aphs aken a baseline and 12 mon hs pos ope a i ely. 1 3 Page 3 o 12 215 Clinical O al In es iga ions (2024) 28:215 S udy popula ion Twen y pa ien s (13 women (65%)) wi h a mean age o 48.59 yea s (SD:10.32), o whom wo we e smok- e s (10%) pa icipa ed in his s udy. The 96.39% o he pa icipan s had mul iple ecessions. A o al o 111 RT2 ecessions we e ea ed (CMX: 58 s. CTG: 53), among which 65 (CMX: 34 s. CTG: 31) we e in he mandible (58.5%). A o al o 31 inciso s (27.92%), 36 canines (32.43%), and 44 p emola s (39.63%) we e included. REC dep h, REC wid h, KTW, GT, and CAL a baseline a e shown in Table 1. Clinical esul s Clinical esul s a 6 mon hs a e summa ized in Table 2. When analyzing he in e g oup esul s, no signi ican di - e ences we e obse ed in any o he pa ame e s analyzed. Clinical esul s a 12 mon hs a e epo ed in Tables 2 and 3, and 4; he changes be ween 6 and 12 mon hs a e shown in Table 3. The pe cen age o MRC was 56.48% on es and 69.72% on con ol si es a 12 mon hs (p = 0.048). Be ween 6 and 12 mon hs, he pe cen age o MRC dec eased om 59.60 o 56.48% in he es g oup The assessmen was made using he Roo Co e age Es he ic Sco e (RES) [37]. S a is ical analysis All he ob ained da a we e analyzed using s a is ical so - wa e (IBM SPSS® S a is ics 20.0; IBM, Chicago, IL, USA), wi h he pa ien as he uni o analysis. Ini ially, he Shapi o–Wilk es was used o e alua e i he dis ibu ion was no mal o no . Fi s , desc ip i e s a is ics we e pe - o med, and means and s anda d de ia ions we e p o ided o quan i a i e a iables, and pe cen ages we e de e mined o ca ego ical a iables. Subsequen ly, in he analysis o s a is ical ela ionships, no mali y es s led o he use o nonpa ame ic es s o bo h in ag oup (Wilcoxon es o he anges o ela ed samples) and in e g oup compa isons (Mann–Whi ney U). Resul s The CONSORT diag am, which shows each g oup and he numbe o pa icipan s, as well as he numbe o d op-ou s, is shown in Fig. 1. Fig. 1 CONSORT diag am 1 3 215 Page 4 o 12 Clinical O al In es iga ions (2024) 28:215 Table 1 Baseline cha ac e is ics o he s udy popula ion Tes (CMX) (n = 0) Con ol (CTG) (n = 20) P alue To al Age (mean ± SD) 48.79 ± 10.35 48.39 ± 10.59 0.73 48.59 ± 10.32 Females n (%) 13 (65%) 13 (65%) > 0.05 13 (65%) Smoke s n (%) 1 (5%) 1 (5%) 2 (10%) REC pe pa ien (mean ± SD) [ ange] 2.9 ± 1.12 [1–5] 2.65 ± 0.99 [1–4] 0.622 2.78 (1.05) [1–5] REC maxilla n (%) 24 (41.38%) 22 (41.51%) > 0.05 46 (41.44%) REC mandible n (%) 34 (58.62%) 31 (58.49%) 65 (58.5%) REC dep h (mm) (mean ± SD) [ ange] 3.69 ± 1.03 [2.25–5.5] 3.67 ± 0.66 [2.25–4.75] 0.968 3.68 ± 0.85 [2.25–5.5] REC wid h (mm) (mean ± SD) [ ange] 4.15 ± 0.73 [2.75–5.5] 3.91 ± 0.68 [2.5–5.5] 0.289 4.03 ± 0.71 [2.5–5.5] CAL (mm) (mean ± SD) [ ange] 4.88 ± 1.12 [3.33–7] 4.95 ± 0.75 [3.25–6.5] 0.565 4.91 ± 0.95 [3.25–7] KTW (mm) (mean ± SD) [ ange] 1.78 ± 1.24 [0–5] 1.77 ± 1.10 [0–4] 0.968 1.78 ± 1.24 [0–5] GT (mm) (mean ± SD) [ ange] 1.09 ± 0.28 [0.5–2] 1.19 ± 0.29 [1–2] 0.365 1.14 ± 0.29 [0.5–2] REC dep h (Recession dep h); REC wid h (Recession wid h); KTW (ke a inized issue wid h); CAL (Clinical a achmen le el); GT (Gingi a hickness); SD (s anda d de ia ion); mm (millime e s); CMX (xenogeneic collagen ma ix); CTG (connec i e issue g a ) Table 2 Clinical esul s a baseline (T0), six (T1) and wel e (T2) mon hs G upo T0T1 T2T0-T1 T0-T2 T1-T2 (baseline) (mean ± SD) (6 mon hs) (mean ± SD) (12 mon hs) (mean ± SD) P in ag oup P in ag oup P in ag oup RECdep h (mm) Tes (CMX) n = 20 3.69 ± 1.03 1.48 ± 0.73 1.55 ± 0.77 < 0.001 < 0.001 0.448 Con ol (CTG) n = 20 3.68 ± 0.66 1.18 ± 0.88 1.11 ± 0.78 0.905 P (in e g oup) 0.968 0.314 0.149 - - - RECwid h (mm) Tes (CMX) n = 20 4.15 ± 0.74 2.83 ± 1.02 2.9 ± 0.94 < 0.001 < 0.001 0.866 Con ol (CTG) n = 20 3.91 ± 0.69 2.38 ± 1.56 2.48 ± 1.58 0.767 P (in e g oup) 0.289 0.478 0.583 - - - KTW (mm) Tes (CMX) n = 20 1.79 ± 1.25 2.36 ± 2.47 1.96 ± 1.09 0.307 0.443 0.623 Con ol (CTG) n = 20 1.78 ± 1.11 2.47 ± 1.3 2.43 ± 1.17 0.004 0.01 0.752 P (in e g oup) 0.968 0.301 0.242 - - CAL (mm) Tes (CMX) n = 20 4.88 ± 1.12 2.53 ± 0.78 2.64 ± 0.79 < 0.001 < 0.001 0.14 Con ol (CTG) n = 20 4.95 ± 0.76 2.35 ± 0.96 2.28 ± 0.87 0.284 P (in e g oup) 0.565 0.738 0.265 - - - REC dep h (Recession dep h); REC wid h (Recession wid h); KTW (ke a inized issue wid h); CAL (Clinical a achmen le el); SD (s anda d de ia ion); mm (millime e s); CMX (xenogeneic collagen ma ix); CTG (connec i e issue g a ) 1 3 Page 5 o 12 215 Clinical O al In es iga ions (2024) 28:215 o all pa ame e s (excep KTW and GT) in he con ol g oup be ween he uppe and lowe jaws, wi h a o able esul s o he maxilla; in he es g oup, he di e ences be ween he maxilla and mandible we e only signi ican o he inc ease in GT. Resul s o he su gical p ocedu e and PROMs No pos ope a i e complica ions we e obse ed a e any su ge y. The esul s a e epo ed in Table 5. The mean su - gical ime was 45 min (SD:9.01), i.e., 41 min (SD:7.6) (CI 95% 37.41–44.59) in he es g oup and 49.15 min (SD:8.5) (CI 95% 45.15–53.15) in he con ol g oup; he di e ences be ween g oups we e signi ican (p = 0.004). Rega ding he assessmen o pain, less pain was epo ed by pa ien s who ecei ed CMX, wi h a VAS = 3.65 (SD:2.08) (95% CI 2.67–4.63) s. VAS = 5.2 (SD:2.31) (95% CI 4.12–6.28) (p = 0.015). Pa ien s in he es g oup we e mo e and an inc eased in he con ol g oup om 68.70 o 69.72%, espec i ely. The CRC was achie ed in 7 pa ien s (35%) in he es g oup and 8 pa ien s (40%) in he con ol g oup Th ee pa ien s p esen ed wi h CRC o all ea ed ecessions in he con ol g oup. A he ecession le el, he pe cen age o CRC dec eased in he es g oup ( om 15.5 o 12.1%), and in he con- ol g oup, i inc eased om 18.9 o 22.6% om 6 o 12 mon hs. Bo h ea men g oups showed signi ican pos -su gi- cal imp o emen in all clinical a iables, excep o he KTW in he es g oup. The GT inc eased a e he su gical p ocedu es: 0.46 mm (SD:0.54) in he es g oup and 0.78 mm (SD:0.47) in he con ol g oup (p = 0.038). An analysis was pe o med by he ea men g oup ( es g oup o con ol g oup) and he esul s a e summa ized in Table 4. S a is ically signi ican di e ences we e obse ed Table 3 Resul s o clinical changes a six (T1) and wel e (T2) mon hs Clinical pa ame e G oup T1 T2 P in ag oup (6 mon hs) (12 mon hs) MRC (%) Tes (CMX) n = 20 59.60 ± 16.23 56.48 ± 19.68 0.167 Con ol (CTG) n = 20 68.70 ± 23.53 69.72 ± 21.21 0.378 P in e g oup 0.163 0.048 CRC (%) Tes (CMX) n = 20 45 35 0.084 Con ol (CTG) n = 20 40 40 0.086 P in e g oup 0.64 0.14 REC ed (mm) Tes (CMX) n = 20 2.21 ± 0.90 2.14 ± 1.07 0.448 Con ol (CTG) n = 20 2.50 ± 0.84 2.56 ± 0.86 0.905 P in e g oup 0.277 0.181 CAL gain (mm) Tes (CMX) n = 20 2.36 ± 0.97 2.64 ± 0.79 0.14 Con ol (CTG) n = 20 2.60 ± 1.10 2.28 ± 0.87 0.284 P in e g oup 0.512 0.221 KTW gain (mm) Tes (CMX) n = 20 0.57 ± 2.08 0.18 ± 0.84 0.623 Con ol (CTG) n = 20 0.69 ± 0.85 0.65 ± 0.92 0.752 P in e g oup 0.174 0.114 GT (mm) Tes (CMX) n = 20 -0.46 ± 0.54 - Con ol (CTG) n = 20 -0.78 ±0.47 - P in e g oup -0.038 MRC (mean oo co e age), CRC (comple e oo co e age), REC ed ( educ ion in ecession); KTW (ke a inized issue wid h); CAL (Clinical a achmen le el); GT (Gingi al hickness); SD (s anda d de ia ion); % (pe cen age); mm (millime e s); CMX (xenogeneic collagen ma ix); CTG (connec i e issue g a ) 1 3 215 Page 6 o 12 Clinical O al In es iga ions (2024) 28:215 sco e in he es g oup (6.7 (SD:1.97)) and in he con- ol g oup (7.28 (SD:2.24)). Clinical and adiog aphic cha ac e is ics and su gical p ocedu es o one pa ien om es g oup and con ol g oup a baseline and 12 mon hs a e shown in Figs. 2 and 3. Discussion To ou knowledge, he e is no double-blind andomized clinical ial in he li e a u e ha compa es he use o a so issue subs i u e such as he CMX s. he CTG o he ea men o RT2 ecessions in combina ion wi h CAF, hus making i di icul o compa e ou esul s wi h ecen e i- dence [6, 27, 30]. The esul s o his s udy indica ed ha he pe cen age o MRC was lowe in he es g oup han in he con ol g oup (CMX: 56.48% s. CTG: 69.72%) (p = 0.048) and ha he pe cen age o CRC was lowe in he es g oup han in he con ol g oup (35% s. 40%) a e 12 mon hs; he e o e, hypo hesis (H0) is ejec ed. Ou esul s pa ially coincide wi h a ecen me a-analysis o Mille classes I and II ecessions [18, 38], in which lowe MRC we e obse ed wi h CMX compa ed wi h CTG, wi h simila CRC in bo h s udy g oups. sa is ied wi h he p ocedu e in gene al, bu he di e ences be ween g oups we e no signi ican . The aes he ic e alua ion sco e a 12 mon hs was 6.85 (SD:1.5) in he es g oup and 7.15 (SD:1.3) in he con ol g oup These alues we e simila o he RES Table 4 Clinical esul s in maxilla and mandible a 12 mon hs o ollow-up Pa ame e T2Loca ion CMX CTG p in e g oup MRC (%) Maxilla (n = 9) 65.01 ± 16.83 83.34 ± 15.68 0.015 Mandible (n = 11) 49.49 ± 19.74 58.58 ± 18.83 0.141 p in ag oup 0.152 0.007 CRC n (%) Maxilla (n = 9) 55.56 77.78 0.034 Mandible (n = 11) 27.28 9.09 0.72 p in ag oup 0.412 0.012 REC dep h (mm) (mean ± SD) Maxilla (n = 9) 2.61 ± 0.97 3.15 ± 0.73 0.297 Mandible (n = 11) 1.76 ± 1.06 2.08 ± 0.67 0.217 p in ag oup 0.08 0.003 REC wid h (mm) (mean ± SD) Maxilla (n = 9) 1.6 ± 0.99 2.5 ± 1.48 0.19 Mandible (n = 11) 0.97 ± 0.89 0.57 ± 0.78 0.332 p in ag oup 0.147 0.001 KTW gain (mm) (mean ± SD) Maxilla (n = 9) 0.16 ± 1.09 0.87 ± 1.07 0.185 Mandible (n = 11) 0.19 ± 0.63 0.46 ± 0.77 0.401 p in ag oup 0.943 0.33 CAL gain (mm) (mean ± SD) Maxilla (n = 9) 2.67 ± 0.97 3.47 ± 0.88 0.222 Mandible (n = 11) 1.89 ± 1.07 2.01 ± 1.03 0.562 p in ag oup 0.08 0.004 GT gain (mm) (mean ± SD) Maxilla (n = 9) 0.81 ± 0.55 0.97 ± 0.48 0.481 Mandible (n = 11) 0.17 ± 0.31 0.64 ± 0.44 0.034 p in ag oup 0.004 0.135 MRC (mean oo co e age), CRC (comple e oo co e age), REC ed ( educ ion in ecession); KTW (ke a inized issue wid h); CAL (Clinical a achmen le el); GT (Gingi a hickness); SD (s anda d de ia ion); % (pe cen age); mm (millime e s); CMX (xenogeneic collagen ma ix); CTG (connec i e issue g a ) Table 5 Pa ien based su gical pa ame e s and pa ien pe cep ion du - ing he su ge y Tes (CMX) Con ol (CTG) in e - g oup p N = 20 (mean ± SD) N = 20 (mean ± SD) Su gical ime (minu es) 41 ± 7.6 49.15 ± 8.5 0.003 RES 6.74 ± 1.97 7.29 ± 2.24 0.309 PROMs VAS pos ope a i e pain 3.65 ± 2.08 5.2 ± 2.31 0.015 VAS clinical expe ience 6.4 ± 2.21 5.35 ± 2.08 0.134 VAS aes he ic 6.85 ± 1.5 7.15 ± 1.3 0.64 Su gical ime: du a ion o he su gical p ocedu e (in minu es); RES ( oo co e age es he ic sco e), PROMs: clinical expe ience using a isual analog scale (VAS) (0 being he wo s p ocedu e and 10 he bes ); pos ope a i e pain using a isual analog scale (VAS) (0 being he leas pain and 10 being he maximum pain). Aes he ic esul as assessed by he pa ien using a isual analog scale (VAS) (0 = wo s possible aes he ic esul and 10 = excellen aes he ic esul ) SD (s anda d de ia ion); mm (millime e s); CMX (xenogeneic collagen ma ix); CTG (connec i e issue g a ) 1 3 Page 7 o 12 215 Clinical O al In es iga ions (2024) 28:215 in ou s udy (35%), hey a e no compa able due o he ype o ecessions ea ed, whe e he REC ed as well as KTW gain should be conside ed a ea men success in he ea - men o gingi al ecessions associa ed wi h loss o in e - p oximal a achmen [44, 45]. In Chamb one’s 2010 me a-analysis [46], o he ea - men o RT1 ecessions, in s udies wi h mo e han 10 pa ien s, a 6 mon hs, he CTG yielded e y he e ogeneous esul s, wi h pe cen ages o MRC (64.5 − 97.3%) and pe - cen ages o CRC (10 − 96.1%) alues ha coincide wi h a p e ious e iew [3]. The e o e, ou MRC esul s (CMX: 56.48% s. CTG: 69.72%) o RT2 ecessions a e encou ag- ing. Howe e , CRC (CMX: 35% s. CTG: 40%) is a om he esul s o ecessions wi hou inse ion loss, which was expec ed based on e idence in he li e a u e [6]. A ecen CRC me a-analysis o 37 publica ions abou hese ypes o ecessions [27] ound wide CRC anges (32.87 − 63.82%). Achie ing CRC o hese ypes o ecessions is conside ed a challenge because o in e p oximal a ach- men loss [47], which implies an inc ease in he a ascula su ace [26, 48]. Ou esul s a e consis en wi h hose p e- iously epo ed [49] o Mille class III ecessions ea ed wi h modi ied unnel echnique (TTM) in combina ion wi h Howe e , he pe cen age o MRC (CMX:56.48% s. CTG: 69.72%) (p = 0.048) and he pe cen age o CRC (CMX:35% s. CTG: 40%) esul s o bo h ea men g oups we e wi hin he anges epo ed in p e ious s udies o RT2 ecessions wi h CAF + CTG a 12 mon hs (54.8- 77.57%) [39–41]. Only, Fe nández-Jiménez e al. [40], 2023, e alua ed he CRC a 12 mon hs in mul iple eces- sions wi h esul s (50%) ha we e sligh ly supe io o hose he ein (40%) whe e he KTW a baseline was highe . The e idence ega ding CMX is limi ed o RT1 eces- sions whe e di e en ea men s ha e been compa ed: (a) CAF + CTG s. CAF + CM [8, 15, 26] (b) CAF s. CAF + CM [23–25, 42, 43]; (c) Modi ied Co onally Ad anced Tunnel (MCAT) + CTG s. MCAT + CM [22, 23]. The pe cen age o MRC wi h CMX a 12 mon hs anged om 76.2% [23] o 94.32% [24]. Ou esul s we e lowe (56.48%) han he cu en e idence, p obably due o he ype o ecessions ea ed in his clinical s udy (RT2) whe e a achmen loss was p esen . Also, only h ee s udies un il now ha e ea ed mul iple ecessions [8, 24, 25] wi h CAF + CMX, and CRC was e alua ed in i e s udies p e i- ously [8, 24–26, 42] and i anged om 36% [42] o 72% [24]. Al hough hese esul s we e supe io o hose ob ained Fig. 3 Su gical in e en ion in a pa ien alloca ed o he CAF + CTG g oup: (g)(h) clini- cal and adiog aphic ea u es a baseline, (i) In a-ope a i e iew: CTG (j) Immedia e pos ope a i e iew: co onally lap ad ancemen and closu e (k)(l) Ou come a 12-mon hs ollow-up Fig. 2 Su gical in e en ion in a pa ien alloca ed o he CAF + CMX g oup. (a)(b) clini- cal and adiog aphic ea u es a baseline, (c) In a-ope a i e iew: CMX, (d) Immedia e pos ope a- i e iew: co onally lap ad ance- men and closu e, (e)( ) Ou come a 12-mon hs ollow-up 1 3 215 Page 8 o 12 Clinical O al In es iga ions (2024) 28:215 s ep o CEJ whose impo ance has been e idenced in he ecen 2018 classi ica ion. Also, he so issue ou comes we e assessed a 12 mon hs, so long- e m obse a ions a e necessa y o con i m hese esul s. Howe e , his is he i s double-blinded RCT in RT2 ecessions ha compa es a CMX and au ogenous g a s, including bo h maxillae (man- dible:58.5%), and mul iple ecessions (96.39%). Conclusions Wi hin he limi a ions o his clinical s udy, al hough MRC was g ea e wi h CTG we conclude ha CMX is a ea men op ion o hese challenging RT2 ecessions. The su gical ime and pa ien mo bidi y we e educed in he es g oup. The e o e, CMX can be conside ed an al e na i e o au olo- gous g a s. I is necessa y o pe o m mo e RCTs in pa ien s wi h pe iodon i is due o he high p e alence o mul iple eces- sions in hese pa ien s, which equi e la ge g a s ha en ail g ea e pos ope a i e mo bidi y. Acknowledgemen s The au ho s would like o hank o he s a om Clínica D . Agui e (Bilbao, Bizkaia, Spain) and Clínica Den al La Casilla, SL (Bilbao, Bizkaia, Spain) o hei collabo a ion. Also, he au ho s would like o hank o he UPV/EHU o p o iding he Open Access unding and o Geis lich Pha ma, AG (Wolhusen/ Swi ze land) o p o iding s udy ma e ials. Au ho con ibu ions Concep ualiza ion: ERdG-P and LAAZ; me h- odology: ERdG-P, MVF, AMGF, and LAAZ; da a collec ion: MVF; o mal analysis and in es iga ion: ERdG-P, MVF, AMGF, and XMM.; w i ing—o iginal d a p epa a ion:ERdG-P and AMGF; w i ing— e- iew and edi ing: ERdG-P and AMGF; supe ision: LAAZ; all he au- ho s e iewed and app o ed he manusc ip . Funding Open Access unding p o ided hanks o he CRUE-CSIC ag eemen wi h Sp inge Na u e. S udy ma e ials we e kindly p o ided by Geis lich Pha ma, AG (Wolhusen/ Swi ze land). Open Access und- ing p o ided by he Uni e si y o Basque Coun y (UPV/EHU), Leioa, Biscay, Spain. Open Access unding p o ided hanks o he CRUE-CSIC ag eemen wi h Sp inge Na u e. Da a a ailabili y No da ase s we e gene a ed o analysed du ing he cu en s udy. Decla a ions E hics app o al All p ocedu es pe o med in s udies in ol ing hu- man pa icipan s we e in acco dance wi h he e hical s anda ds o he ins i u ional and/o na ional esea ch commi ee and wi h he 1975 Helsinki Decla a ion ( e ised in 2013) and i s la e amendmen s o compa able e hical s anda ds. Consen o pa icipa e In o med consen was ob ained om all indi- idual pa icipan s included in he s udy. CTG, whe e di e ences be ween he MRC (83%) and he CRC (40%) we e epo ed. The di e ences wi h ou esul s in MRC could be due o he su gical echnique [39] and/o he cha ac e is ics o he sample (ou ecessions we e wide and had a lowe KTW). Ad an ages o using al e na i e ma e ials include he educ ion in in aope a i e ime and pa ien mo bidi y [8], indings ha we e con i med in his RCT. A educ ion in su - gical ime o 8 min was obse ed in ou s udy, less han ha ob ained in a ecen s udy [50], whe e RT1 ecessions we e ea ed (15 min). Pa ien sa is ac ion was gene ally highe in he es g oup, which also p esen ed lowe mo bidi y (p = 0.015); hese indings con i m p e ious esul s [8], in which he eco e y ime o pa ien s was sho e (1.8 days) in he CMX g oup, hus a o ing a be e assessmen o he ea men ecei ed. Ano he objec i e o hese p ocedu es is o inc ease ke a- inized issue [18], which is key in ecessions wi h ine phe- no ypes and in main aining he GM in he long e m [51, 52]. I has been epo ed ha KTW gains a e highe wi h CTG han wi h CMX, bu wi hou being signi ican [18], which coincides wi h ou esul s a 6 mon hs, bu no a 12 mon hs, whe e a g ea e dec ease in KTW was obse ed in he CMX g oup. The e idence o inc eased GT wi h CMX s. CTG is limi ed [25]; in his s udy, a 12 mon hs, he e was a end o inc eased GT wi h he CTG (0.32 mm, p = 0.056), coin- ciding wi h a di e ence o 0.23 mm in a o o CTG in he s udy by Ca da opoli e al. [26]. In he CMX g oup, he hickness gain was g ea e in he uppe maxilla (p = 0.004), unlike in he con ol g oup, whe e he di e ences be ween he maxilla and mandible we e no signi ican . The main indica ion o he ea men o ecessions is aes he ic demand [53]. The e is no consensus on which app oach yields mo e aes he ic esul s conce ning CRC o he simila i y o ea men issue wi h adjacen is- sue [4, 45]. In ou s udy, he aes he ic assessmen by he pa ien s was high and simila in bo h g oups (CMX: 6.85 (SD:1.5) s. CTG: 7.15 (SD:1.3)), a inding ha coincides wi h p e iously epo ed esul s [24], whe e no di e ences we e obse ed be ween g oups. In con as , a ecen s udy ob ained a mo e na u al ex u e and con ou wi h CMX han wi h a CTG [54]. When he p o essional assessmen was pe o med he RES was simila be ween g oups (CMX: 6.70 (SD:1.97) s. CTG: 7.28 (SD:2.24)) and compa able o esul s epo ed in he li e a u e [23], i.e., RES o 7.85 (SD:2.42) o CMX and 7.34 (SD:2.90) o CTG. The e o e, bo h ea men modali ies achie ed sa is ac o y aes he ic esul s o bo h p o essionals and pa ien s. Al hough his RCT shows new and ele an in o ma ion on he ea men o RT2 ecessions, i is no exemp om limi a ions. Fi s , he e was he lack o assessmen o he lap hickness ma gin in su ge y o he p esence o de ec able 1 3 Page 9 o 12 215