別紙42 信果程博士(和文))令和 2年01月

応用化学・生命工学専攻

今女窮舌?弄号'

第 169401号
指導教員

伊津野真一

原口直樹

08日

井波智鶴

氏名

論文内容の要旨(博士)
博士学位論文名トリブチルボランを重合開始剤とした歯科用高分子材料の研究(要旨 1,200字程度)

多くの歯を残すととで心身的健康状態を保ち, QOL を向上することは国際的な健康課題として掲げられてぃる.従来,「歯を削る」治療を主としていた歯科治療は「歯を残す」,「歯を再生する」治療へと移行している

トリブチルボラン(TBB)は,1971年に「歯科用接着性材半羽の重合開始剤として米国で製品化された.歯科で使用される一般的な開始剤と比較してTBBを重合開始郵ルする材料は歯質接着性が高い
こと,残存する未反応モノマーが少ないなど歯科・材料として望ましい特長を有することが報告されている. TBB は長きにわたり「歯科用接着性材料」として歯科治療の進歩に大きく貢献してきたが, TBBの特性を活かすことで「歯を残す」,「歯を再生する」次世代の歯科,材料への展開が期待できる
そこで本研究では, TBB を重合開始斉1ルした「歯の保存を可能とする新しい高分子材料」を開発することを目的とした第一章では,口腔保健の意義と歯科材料が担う役割にっいて述べた.剛控状態が全身健康に及ぽす影
響を明らかにし,歯科治療,材料の分類と材料に求められる要件を概説した第二章では, TBB と他の重合開始斉1ルの違い, TBB の利点および生体適合性を説明し,本研究の意
義と目的を明確にした第三章では,歯科・で一般的に使用される過酸化べンゾイルとアミン(BPO/アミン)を重合開始邦ルしたメタクリル酸メチル(MMA)の重合挙動と TBB のそれを比較した. TBB による MMA の転化率がBPO/アミンより高く,生成したポリマーの分子量が 2 倍以上となることを明らかにした.更に, TBBのラジカル強度が長期間に渡って保たれ, TBB によって調製したポリマーが重合開始剤機能を有することを見出した

第四章では,本研究において TBB と組み合わせた無機材半斗である mineraltrioxideaggregate (MTA)の特長と歯科.における用途や効果拶甫凱こっいて説明した上で,1BB と組み合わせる意義にっいて述べた

第五章では,従来のMTA材料の操作性と辺縁圭M拠陛を向上した新規材料を設計,歯科材料として必要な諸物性の付与ど性状調整を行った.加えて,実使用を想定した保存安定性試験や細胞毒陛試験を行い,最終組成を決定した

第六章では,歯科治療の予後を左右する重要な因子である歯冠修復物の辺縁圭H貰陛にっいて,新規材料と従来型の材料との比較評価を行い,第五章で開発した新規材'料が優れた辺縁圭"拠性を有する材料であることを示した

第七章では,新規材料の物理化学的特性を,臨床使用されている光化学重合性MTA材料(既存材料)との比較により評価し,新規材料の物理化学的特性が優れていることを明らかにした第八章では, MTA 材料の最も重要な機能である「生体適合性」と「硬組織再生誘導能」を,イヌを用いた臨床使用模擬試験により評価した.新規材料の炎症性反応は既存材料と同等以下であり,硬組織再生誘導能は既存材料よりも高いことを示した
第九章では,新規材料の臨床への展開と課題について述べた別紙4

1 (課程博士(英文))Date of sublnission (1nonth day, year)

01/08/2020

Department

Department ofApplied
Chemistry and Life

StudentlD Nulnber

Science

D169401

Shlnichiltsuno
Supervisors

NaokiHaraguchi
ChidzuN lnami

Applica11t's nalne

Abstract (Doctor)
Title ofThesis

Study on dental polylner lnatedals using tri・butylborane as a polylnerization initiator

Approx.80o words
Much attention to keep healthy state and to ilnprove the quality ofHfe has been attracted as worldwide concem.
It is ilnportant to preserve many teeth for the lnaintenance of mental and physical health. For this reason,
dental treatmel〕t is shifting from "dri11ing teeth" to "preserving teeth" or "regenerating teeth".
Tri・butylborane (TBB) was coln1ΥlerciaHzed in 1971 as a polylnetization initiator for dental adhesivematerial.1t was reported that dental materials using TBB as a polymerization initiator showed higher toothadhesion and less residua11nonolner compared to generalinitiators used in dentistry. TBB has long
Contributed to the advancement of dentaltreatment as an "adhesive material" for dental use. Furthermore,
it is expected that TBB can be expanded into new dental materials for " preserving teeth" or "regeneratingteeth". The purpose of this study was to develop "a new polymer materialthat can preserve teeth" usingTBB as a polylnerization initiator.
In chapter l, the significance of oral health and the role played by dental materials were described. The
effects of oral condition on general health were clarified.1hen, dental treatment, classiacation ofn〕aterials, and requlrements of denta11natetials were outlined.
In chapter 2, the difference between lBB and other polymerization initiators, the advantages of TBB attl〕e tooth interface, and biocolnpalibility 、刃ere explained.1n addition, we lnentioned the significance andPurpose of this study.
In chapter 3, the polymerization behavior of lnetl〕y11nethacrylate (NIMA) using TBB was compared withthat ofbenzoyl peroxide and alnine (BPO/amine) as polylnerization initiators colnlnonly used in dentistry.
As a result, we clarified that the conversion of MMA by TBB 、vas higher than that of BPO/amine.
Furthermore, the molecular welght of polymer produced by TBB was more than twice as b地 as that ofBPO/amine.1n addition, we found thatthe radicalintensity ofpolymerization by TBB was n〕aintained fora long tilne, and the polymer that was prepated by TBB had a polymerization initiator function.
In chapter 4, the features and ef負Cacies of mineraltrioxide aggregate (MTA), which is an inorganic
Inaterial colnbined with TBB W由'e outHned. Then, the sionificance of colnbining TBB and MTA wasdescrlbed.

In chapter 5, we designed a ne、刃 material that ilnproves the operability and seaHng・ability of theConventional MTA lnaterial. The reactivity of lnonolner, X・ray contrast agent, and colnposition of
Inaterials were investigated.1n addition, storage stability tests and cytotoxicity tests were perforlned
assluning cHnical use, and the flnal colnposltion was deterlnined.

In chapter 6, a colnparative evaluahon of the new N11A material and the conventional MIA lnaterial wasCarried out to evaluate the marginal sealing・ability of the crown restoration. The lnarσinal sealing・ability
is an important factm'that detem〕ines the prognosis of dentaltreatment.1n this chapter, it was shown thatthe new MTA material has exce11ent maroinal sealing・ability.

In chapter 7, the physicochelnical properties of the new MIA lnaterials were evaluated by comparison、vith Hght・curable MTA materials already used cHnica11y, As a result, we clarified that the new MIA
material has the exce11ent physicochemical properties.
In chapter 8,"biocompatibility" and "hard tissue regeneration inducing ability" that were the mostilnportant functions of NITA materials were evaluated by a clinical use silnulation test using dogs, As aresult, the inaammatory changes by the new MTA material was less than or equalto that of the existing
MTA material. Thus, we considered that the new MTA material can be used clinica11y. Furthennore, theCondition ofthe hard tissues that were regenerated by applying the new MTA materlal was superior to that
Ofthe existing MTA material、In chapter 9, the clinical application of new MTA lnatetials and their cha11enges were described.