16
BIOLOGICAL EVALUATION OF COCR DENTAL ALLOY FOR
SELECTIVE LASER MELTING AND 3D PRINTING.
(
A PILOT STUDY)
Tomova, Z., Vlahova, A., Chonin, A., Georgiev, Zh., Alexandrov, Sv.
Faculty of Dental Medicine, Medical University - Plovdiv, Bulgaria
Abstract
: Free metal ions from dental alloys may cause allergic, cytotoxic or
pathogalvanic reactions. The presence of free cobalt ions is tested by a quantitative
reaction. Saliva samples are taken for checking the presence of metal ions and
isoprostanes. Open circuit potential measurements are conducted before and after fixing
the PFM crowns produced by SLM and 3D printing.
Key words
: base dental alloys, SLM, free Cobalt ions
Introduction
: CAD/CAM technologies provide fast production of precise dental
restorations. There are two main ways of making the metal copings when using digital
methods - milling and 3D printing (selective laser melting (SLM)). Biocompatibility of
PFM restorations depends on the ion emission from the metal infrastructure. Free
Cobalt ions may cause allergic, cytotoxic, or even carcinogenic reactions in human
div. Ion release from metal objects in the oral cavity may be a reason for symptoms
of pathogalvanism.
The aim
of the study is to evaluate the biological properties of a dental alloy 3D
printing via SLM regarding the presence or absence of free Cobalt ions.
Materials and Methods
: PFM crowns were produced for 18 patients using CAD/CAM technology. After taking digital impressions, the metal copings were designed, and the files were sent to the 3D printer EOS M100, Germany, present at the
CAD/CAM Center of FDM-Plovdiv for selective laser melting of the dental alloy. 3D printed resin models were used for completing the PFM restorations (Fig.1). 3D printed copings made of CoCr dental alloy EOS CobaltChrome SP2 (EOS,
Finland) were tested for presence of free Cobalt ions using “Chemo Cobalt Test” (Chemotechnique Diagnostics, Sweden). Reaction between nitroso-R-salt and free cobalt leads to change in color of the cotton tip from white to reddish-brown.
Copings were tested at several stages of production process - after 3D printing, after stress relieving, after preparation for porcelain firing and after restoration is completed. Additional testing was performed after stay of the copings in distilled
water.
Fig.1. PFM crowns produced by CAD/CAM technology and SLM of the metal
Fig. 2. Testing after 3D printing of the copings.
17
copings. Saliva samples from the patients were taken before, 2 hours and 7 days after
fixing the crowns in the oral cavity. Open circuit potential measurements were
conducted at the same intervals using apparatus Dentotest Six (Atlantis OOD,
Bulgaria).
Results and Discussion: Copings tests were positive for free Cobalt ions at all
stages during production of PFM restorations (Fig. 2,3). Negative reaction was found
only at the copings after 3-day stay in distilled water (Fig.4). Results indicated that there
is a risk of potentially harmful ion emission from the metal copings. The intensity of
coloration may indicate the concentration of free Cobalt ions. An additional treatment
of the copings may reduce the level of free Cobalt probably due to forming of stable
oxide layer. Further investigations are needed. Saliva testing for Cobalt ions is planned
using ICP-MS. A method for detecting isoprostanes in saliva as a marker of oxidative
stress due to free metal ions is in process of validation. Results of open circuit potential
measurements are in statistical processing.
Conclusion
: The presence of free Cobalt ions requires further studies on the
biological properties of dental CoCr alloy for selective laser melting and 3D printing.
This pilot study was funded by Grant NO-01/2020 of Medical University- Plovdiv,
BULGARIA.
References
1.
Tulyaganov, Dilshat U., et al. "In Vivo Evaluation of 3D-Printed Silica-
Based Bioactive Glass Scaffolds for Bone Regeneration." Journal of Functional
Biomaterials 13.2 (2022): 74.
2.
Lukovskaya, E. V., Bobyleva, A. A., Pekhk, T. I., Dubitskaya, N. F.,
Petrushenkova, I. A., & Belikova, N. A. (1988). Interaction of cis-bicyclo (4.3. 0) nona-
3, 7-diene with iodine. Synthesis of tricyclo (4.3. 0.0 3, 7) nona-4, 8-diene (brexa-4, 8-
diene). Zhurnal Organicheskoj Khimii, 24(7), 1457-1463.
3.
Флейшер,
Григорий. Пропедевтика
детской
ортопедической
Fig. 3. Testing before porcelain firing.
Fig. 4. Testing after stay in
distilled water.
18
стоматологии. Руководство для врачей. Litres, 2022.
4.
Расулова, Ш., et al. "Обоснование к учёту вертикального компонента
роста при диагностике и планировании лечения у пациентов с дистальным
прикусом." Медицина и инновации 1.1 (2021): 101-104.
БОЛАЛАР ПУБЕРТАТ ЁШИДА ОҒИЗ БЎШЛИҒИНИНГ
МАЛАКАЛИ ГИГИЕНАСИНИ РИВОЖЛАНТИРИШ
Аббасова Д.Б., Арипов М.А.
Ташкент давлат стоматология институти
Калит сўзлари:
Оғиз бушлиғи, гигиена, фтор, эритрозинли буёқ.
Долзарблиги.
Оғиз бўшлиғининг малакали гигиенаси - бу оғиз бўшлиғи
тишлар юзасидан юмшоқ карашларни, тиш чўкмаларини(тошларини) махсус
асбоб- ускуналар ёрдамида мутахассис томонидан маълум қоидаларга риоя
қилинган ҳолда тозалашдан иборат муолажадир. Бугунги кунда болалар ўртасида
амалга ошириладиган оғиз бўшлиғининг малакали гигиенаси тадбири
стоматологик касалликлар комплекс профилактикаси элементларидан бирига
айланган. Буларга:
1.
Болаларни рационал овқдтланишини таъминлаш.
2.
Фтор сақловчи воститаларни маҳдллии қўллаш.
3.
Оғиз бўшлиғи гигиенасининг мунтазамлигини таъминлаш.
4.
Малакали гигиенани амалга ошириш.
Мазкур дастурга мувофиқ оғиз бўшлиғининг малакали гигиенасини амалга
оширишлар орасидаги вақт болаларда 2-3 ҳафтани ташкил қилган, чунки зич
карашлар мавжуд пайтида гингивит белгилари ва бошланғич кариес
ривожланиши учун тахминан шунча вақт етарли. Бугунги кунда оғиз бўшлиғи
малакали гигиенасини амалга ошириш вақти болада шу муолажага нисбатан
талаб пайдо бўлиши билан боғлиқ қилиб белгиланган.
Материаллар ва тадқиқот усуллари.
1.
Барча тишлар йодли ёки эритрозинли буёқ билан бўялади. Шифокор
беморга тишлар қаторидаги караш кўпроқ йиғиладиган соҳаларни ойна оркали
кўрсатади. Беморларга тишларни туғри ювиш қоидалари ўргатилади ва амалга
оширилади.
2.
Тишни чўтка ва пасталар билан тозалангандан сўнг колган тиш
карашларини абразивли фтор сакловчи силликловчи махсус пасталар ёрдамида
тозаланади. Абразив модда сифатида асосан диоксид кремнийдан
фойдаланилади. Фторидлар концентрацияси абразив тозаловчи пасталарда
0,1%(0,22%- МАГ ёки 0,8%- МАР03Н
1
) ни ташкил этадиТишларнинг чайнов
юзасидан карашлар айланувчи махсус чўткалар ёрдамида, силлик юзалардан эса-
юмшок резина калпокчалар ёрдамида абразив паста билан тозаланади. Бунда
абразив паста тутган чўтка ва резина калпокчалар айланиш тезлиги 5000 айл/сек
ташкил этиши керак.Тишларнинг контакт (апроксимал) юзалари флосслар
ёрдамида тозаланиши лозим.
3.
Тишлар юзаси карашлардан тозаланиб бўлгандан сунг тиш тозалиги
даражасини назорат килиш керак булади. Мустакил назорат учун болаларга уйда
