The Materials Lab: Biomaterials in Modern Dentistry https://the-materials-lab.transistor.fm Transistor (https://transistor.fm) https://feeds.transistor.fm/the-materials-lab The chemistry of how teeth decay and recover, and the materials that help them rebuild, explained through dentistry's shift from drilling and filling to prevention and minimal intervention. Conversations go below the headline: why a slow release of fluoride grows acid-resistant fluorapatite while a burst forms calcium fluoride, how bioactive glasses release calcium, phosphate and other ions, how formulations are tested, and how better materials reach the clinic. With Dr Saroash Shahid, Reader in Dental Biomaterials at the Institute of Dentistry, Queen Mary University of London. For dental students, hygienists, therapists, dentists, dental technicians, industry and public health professionals, regulators, and curious listeners. © 2026 Aloudable Ltd 64ad241c-b990-59be-bc80-1831ab4362e4 yes en Tue, 10 Nov 2026 06:08:09 +0000 Tue, 10 Nov 2026 06:09:05 +0000 https://img.transistorcdn.com/51LH22tj1T2ggjnTDV4PpdKmr5ys2sqtVEsD4eoXctM/rs:fill:0:0:1/w:1400/h:1400/q:60/mb:500000/aHR0cHM6Ly9pbWct/dXBsb2FkLXByb2R1/Y3Rpb24udHJhbnNp/c3Rvci5mbS85ZTI3/NzI2NTI4YjgyN2E0/Nzc1OWU1Zjk1YTBl/MGIxZS5qcGc.jpg The Materials Lab: Biomaterials in Modern Dentistry https://the-materials-lab.transistor.fm episodic Saroash Shahid The chemistry of how teeth decay and recover, and the materials that help them rebuild, explained through dentistry's shift from drilling and filling to prevention and minimal intervention. Conversations go below the headline: why a slow release of fluoride grows acid-resistant fluorapatite while a burst forms calcium fluoride, how bioactive glasses release calcium, phosphate and other ions, how formulations are tested, and how better materials reach the clinic. With Dr Saroash Shahid, Reader in Dental Biomaterials at the Institute of Dentistry, Queen Mary University of London. For dental students, hygienists, therapists, dentists, dental technicians, industry and public health professionals, regulators, and curious listeners. The chemistry of how teeth decay and recover, and the materials that help them rebuild, explained through dentistry's shift from drilling and filling to prevention and minimal intervention. Aloudable No No What one drop of SDF turns into on a decayed tooth 2 2 What one drop of SDF turns into on a decayed tooth full cbc931e2-a63e-43b7-831b-69488dfd29ea https://the-materials-lab.transistor.fm/episodes/what-one-drop-of-sdf-turns-into-on-a-decayed-tooth Silver diamine fluoride arrives as one clear drop of silver, fluoride and ammonia. On decayed dentine, Saroash explains, it reacts with saliva and light to form a mixed layer of fluorapatite, calcium fluoride, silver salts and silver metal that lodges in the dentine tubules. The question at the centre is how that layer arrests decay and why it turns the tooth black.

Listeners will come away understanding why the stain is the same chemistry as black-and-white film, how chloride from saliva changes what forms, and why the layer protects by degrading under acid and releasing more ions rather than hardening. Saroash sets out what fluorine NMR shows, where his lab model stops, and how clinical trials in children confirm caries arrest. He also covers SDF with uncooperative children, its place in NHS guidance during COVID, and whether silver interferes with reparative dentine.

00:00 Intro
00:43 Three ingredients in one clear drop
02:50 Why it turns black: light, not the tooth
04:06 Saliva joins in, and dentine holds on
06:57 Not neat stripes: reading the layer with NMR
09:16 Where the lab model stops, and what trials confirm
11:00 A sacrificial barrier, not a hard shell
13:05 At the chair: uncooperative children and COVID
14:41 An orchestra, and what a year-long study should ask
16:53 From the Far East to Western clinics

]]> Silver diamine fluoride arrives as one clear drop of silver, fluoride and ammonia. On decayed dentine, Saroash explains, it reacts with saliva and light to form a mixed layer of fluorapatite, calcium fluoride, silver salts and silver metal that lodges in the dentine tubules. The question at the centre is how that layer arrests decay and why it turns the tooth black.

Listeners will come away understanding why the stain is the same chemistry as black-and-white film, how chloride from saliva changes what forms, and why the layer protects by degrading under acid and releasing more ions rather than hardening. Saroash sets out what fluorine NMR shows, where his lab model stops, and how clinical trials in children confirm caries arrest. He also covers SDF with uncooperative children, its place in NHS guidance during COVID, and whether silver interferes with reparative dentine.

00:00 Intro
00:43 Three ingredients in one clear drop
02:50 Why it turns black: light, not the tooth
04:06 Saliva joins in, and dentine holds on
06:57 Not neat stripes: reading the layer with NMR
09:16 Where the lab model stops, and what trials confirm
11:00 A sacrificial barrier, not a hard shell
13:05 At the chair: uncooperative children and COVID
14:41 An orchestra, and what a year-long study should ask
16:53 From the Far East to Western clinics

]]> Tue, 10 Nov 2026 06:08:09 +0000 Saroash Shahid Watch on YouTube Saroash Shahid 1230 Silver diamine fluoride arrives as one clear drop of silver, fluoride and ammonia. On decayed dentine, Saroash explains, it reacts with saliva and light to form a mixed layer of fluorapatite, calcium fluoride, silver salts and silver metal that lodges in the dentine tubules. The question at the centre is how that layer arrests decay and why it turns the tooth black.

Listeners will come away understanding why the stain is the same chemistry as black-and-white film, how chloride from saliva changes what forms, and why the layer protects by degrading under acid and releasing more ions rather than hardening. Saroash sets out what fluorine NMR shows, where his lab model stops, and how clinical trials in children confirm caries arrest. He also covers SDF with uncooperative children, its place in NHS guidance during COVID, and whether silver interferes with reparative dentine.

00:00 Intro
00:43 Three ingredients in one clear drop
02:50 Why it turns black: light, not the tooth
04:06 Saliva joins in, and dentine holds on
06:57 Not neat stripes: reading the layer with NMR
09:16 Where the lab model stops, and what trials confirm
11:00 A sacrificial barrier, not a hard shell
13:05 At the chair: uncooperative children and COVID
14:41 An orchestra, and what a year-long study should ask
16:53 From the Far East to Western clinics

]]> No Fluoride varnish: why formulation matters more than concentration 1 1 Fluoride varnish: why formulation matters more than concentration full 45a2dfa0-31b2-490c-be14-485cf194c3cf https://the-materials-lab.transistor.fm/episodes/fluoride-varnish-why-formulation-matters-more-than-concentration Saroash explains why fluoride varnishes do not all behave the same way. Fluoride reacts readily with calcium in saliva, so a fast burst mostly forms calcium fluoride. That form is insoluble, washes away, and stays stable at the acidic pH where a reservoir would be needed. A slow release gives fluoride time to replace the hydroxyl group in hydroxyapatite and form fluorapatite, a more stable, acid-resistant crystal. The question at the centre is what in a formulation decides which of the two forms.

Listeners will learn why a fluorapatite layer a few microns thick is enough, and why phosphate-free varnishes can still remineralise using phosphate from saliva. Saroash sets out how pure hydroxyapatite, the carbonated apatite in real enamel and fluorapatite dissolve at different pH, why enamel varies between teeth and people, why primary teeth are more vulnerable, and why published work favours low, repeated doses over one large one.

00:00 Intro
00:45 Why fluoride has to arrive slowly
03:01 The calcium fluoride 'bank' that never opens
04:33 A few microns is enough, and saliva supplies the phosphate
06:22 Three crystals, three critical pHs
09:06 Low and repeated beats one big dose

]]> Saroash explains why fluoride varnishes do not all behave the same way. Fluoride reacts readily with calcium in saliva, so a fast burst mostly forms calcium fluoride. That form is insoluble, washes away, and stays stable at the acidic pH where a reservoir would be needed. A slow release gives fluoride time to replace the hydroxyl group in hydroxyapatite and form fluorapatite, a more stable, acid-resistant crystal. The question at the centre is what in a formulation decides which of the two forms.

Listeners will learn why a fluorapatite layer a few microns thick is enough, and why phosphate-free varnishes can still remineralise using phosphate from saliva. Saroash sets out how pure hydroxyapatite, the carbonated apatite in real enamel and fluorapatite dissolve at different pH, why enamel varies between teeth and people, why primary teeth are more vulnerable, and why published work favours low, repeated doses over one large one.

00:00 Intro
00:45 Why fluoride has to arrive slowly
03:01 The calcium fluoride 'bank' that never opens
04:33 A few microns is enough, and saliva supplies the phosphate
06:22 Three crystals, three critical pHs
09:06 Low and repeated beats one big dose

]]> Tue, 03 Nov 2026 12:15:28 +0000 Saroash Shahid Watch on YouTube Saroash Shahid 637 Saroash explains why fluoride varnishes do not all behave the same way. Fluoride reacts readily with calcium in saliva, so a fast burst mostly forms calcium fluoride. That form is insoluble, washes away, and stays stable at the acidic pH where a reservoir would be needed. A slow release gives fluoride time to replace the hydroxyl group in hydroxyapatite and form fluorapatite, a more stable, acid-resistant crystal. The question at the centre is what in a formulation decides which of the two forms.

Listeners will learn why a fluorapatite layer a few microns thick is enough, and why phosphate-free varnishes can still remineralise using phosphate from saliva. Saroash sets out how pure hydroxyapatite, the carbonated apatite in real enamel and fluorapatite dissolve at different pH, why enamel varies between teeth and people, why primary teeth are more vulnerable, and why published work favours low, repeated doses over one large one.

00:00 Intro
00:45 Why fluoride has to arrive slowly
03:01 The calcium fluoride 'bank' that never opens
04:33 A few microns is enough, and saliva supplies the phosphate
06:22 Three crystals, three critical pHs
09:06 Low and repeated beats one big dose

]]> No