My friend who is a dentist says that brushing should last for two minu

My friend who is a dentist says that brushing should last for two minutes and you shouldn't keep the toothpaste inside your mouth for longer periods, more than two minutes. After two minutes, it should be rinsed off because if it is kept for longer time, beneficial bacteria may also die and harmful bacteria can grow, leading to increased risk of infections and possibly even infective endocarditis. So he advises to limit to two minutes only because I used to keep it for at least 10 to 15 minutes. I would spit after brushing, but I would rinse only after 15 minutes.

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Here is a thorough breakdown of what the evidence actually says:

Two-Minute Brushing: Correct Advice

Your friend is right that two minutes is the recommended brushing duration. This is supported by the American Dental Association (ADA), the UK's Oral Health Foundation, and virtually every major dental body. Most people brush for under 60 seconds, so this guidance matters. However, the reasoning he gave for the two-minute limit needs some unpacking.

The "Rinse After 2 Minutes" Claim: Partly Wrong

This is where your friend's reasoning gets mixed up. Here is what the evidence actually shows:

Fluoride is the key ingredient - and you want to keep it on your teeth longer, not wash it off

Fluoride in toothpaste works by remineralizing tooth enamel and making it more acid-resistant. For this to happen, fluoride needs contact time with the teeth.
An RCT published in BMC Oral Health (2022, PMID 35241051) confirmed that not rinsing with water after brushing significantly raises salivary fluoride concentrations, meaning more protective fluoride stays in contact with your teeth.
The ADA's own consumer advisor, Dr. Edmond Hewlett, recommends spitting out toothpaste but NOT rinsing with water, so the fluoride remains on the enamel longer.
The UK's Oral Health Foundation, NHS, and major dental bodies all currently advise: spit, don't rinse.
Professional fluoride treatments at the dentist involve even higher fluoride concentrations, and patients are told not to rinse, eat, or drink for 30 minutes afterward. This is the opposite of your friend's advice.

So your habit of waiting ~15 minutes before rinsing was actually closer to best practice for fluoride retention than rinsing immediately after brushing.

The "Harmful Bacteria / Infective Endocarditis" Claim: Not Supported

This is the part of your friend's advice that is not well-founded:

Toothpaste residue does not selectively kill beneficial bacteria and allow harmful ones to proliferate. The oral microbiome does shift briefly after brushing, but research (The Conversation, 2025) shows it recovers quickly and the disruption is temporary. There is no evidence that leaving toothpaste residue for 10-15 minutes after spitting causes a harmful dysbiosis.
Standard fluoride toothpaste does not have a prolonged broad-spectrum antibacterial effect strong enough to cause lasting microbiome disruption. Some toothpastes contain stannous fluoride or zinc compounds that have modest antibacterial effects, but these do not "wipe out" beneficial bacteria over 15 minutes.
The infective endocarditis (IE) link does not apply here. IE from an oral source typically arises from transient bacteremia - bacteria entering the bloodstream during invasive dental procedures (extractions, scaling) or even vigorous brushing itself. It is not caused by toothpaste residue sitting in the mouth for a few minutes. The IE risk is managed by antibiotic prophylaxis before dental procedures in at-risk patients, not by limiting toothpaste contact time.

What You Should Actually Do

Practice	Evidence-Based Recommendation
Brushing duration	2 minutes, twice daily - correct
After brushing	Spit out excess toothpaste
Water rinse	Avoid rinsing with water immediately - or wait at least 10-30 minutes
Mouthwash	If using non-fluoride mouthwash, wait at least 20-30 minutes after brushing
Eating/drinking	Wait at least 10 minutes after brushing

Bottom Line

Your friend is right about brushing for two minutes. But the advice to rinse at the two-minute mark to protect against bacterial overgrowth and IE is not supported by evidence. In fact, it contradicts current dental guidance: you should spit and not rinse, allowing fluoride to stay on your teeth. Your old habit of waiting 15 minutes before rinsing was actually more aligned with best practice, except that ideally you would avoid rinsing with water altogether (or wait even longer). The IE reasoning your friend gave is a misconception - IE risk from oral sources has a completely different mechanism.

My friend also suggested me to use dentine 91 toothpaste, the enamel pro toothpaste. Currently I am using Sensodyne Pronamel toothpaste. But then I checked the Sensodyne Pronamel has fluoride, whereas the dentine 91 does not have any fluoride and they claim that it doesn't contain, it is fluoride-free, which is superior for longevity of the teeth.

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Excellent - I now have very solid data to give you a thorough, evidence-based answer. Here it is:

What Is Dente91 Enamel Pro?

Dente91 Enamel Pro (an Indian brand by Enavant Research Pvt Ltd) is a fluoride-free toothpaste whose active remineralizing ingredient is nano-hydroxyapatite (nHA), combined with xylitol and lactoferrin. It contains no sodium fluoride or stannous fluoride. The claim that "fluoride-free is superior for tooth longevity" is a marketing position, not a settled scientific fact.

What the Evidence Actually Says

1. Fluoride toothpaste: 70+ years of strong evidence

Two landmark Cochrane systematic reviews tell the story clearly:

Marinho et al., Cochrane 2003 (PMID 12535435) - a meta-analysis of fluoride toothpastes for preventing dental caries in children and adolescents, confirming significant caries reduction.
Walsh et al., Cochrane 2019 (PMID 30829399) - a network meta-analysis confirming that fluoride toothpastes at concentrations of 1000 ppm and above significantly prevent caries, with a dose-response relationship (higher fluoride = better protection).

Fluoride works through two mechanisms: it remineralizes early lesions and forms fluorapatite, a harder, more acid-resistant crystal structure than natural hydroxyapatite. This is the most well-documented preventive dental intervention in the history of public health.

2. Nano-hydroxyapatite: a legitimate but newer and less proven alternative

The ingredient in Dente91 - nano-hydroxyapatite - is not a scam. It has a genuine scientific rationale: since tooth enamel is ~96% hydroxyapatite, applying it topically can theoretically help fill micro-defects and remineralize enamel. Two recent systematic reviews address this:

Limeback et al., Can J Dent Hyg 2021 (PMID 34925515) - a systematic review and meta-analysis on biomimetic hydroxyapatite and caries prevention found promising results, but noted that the evidence base is still much smaller than that for fluoride.
Pawinska et al., J Dent 2024 (PMID 39471896) - an updated systematic review and meta-analysis from December 2024 found that hydroxyapatite does show clinical evidence of caries prevention, but concluded the overall quality and volume of evidence is not yet equivalent to that for fluoride.

So nHA is a real ingredient with real benefit, not pseudoscience - but it has not overtaken fluoride in evidence quality.

3. The "fluoride-free is superior" claim - is it justified?

No, not currently. Here is why:

Factor	Sensodyne Pronamel (fluoride)	Dente91 Enamel Pro (nHA, fluoride-free)
Evidence base	70+ years, multiple Cochrane reviews	~10-15 years, growing but smaller
Cavity prevention	Proven, well-quantified	Promising, not yet equivalent
Enamel remineralization	Yes (fluorapatite formation)	Yes (hydroxyapatite deposition)
Crystal hardness	Fluorapatite is harder than natural enamel	Restores to natural enamel hardness
Sensitivity relief	Potassium nitrate in Pronamel directly addresses sensitivity	Not a primary feature
Regulatory approval	ADA-accepted, NHS recommended	Not ADA accepted; no major regulatory endorsement as equivalent
Who might prefer it	Anyone needing proven caries protection	Those who want to avoid fluoride for personal/philosophical reasons

4. Why do some people avoid fluoride?

There is a growing consumer movement away from fluoride based on concerns about:

Dental fluorosis (white spots on teeth from excess fluoride during childhood development)
Systemic fluoride concerns (though the amount absorbed from brushing and spitting is minimal)

These concerns are not entirely baseless for children under 6 who may swallow toothpaste, but for adults who spit, the fluoride absorbed from brushing is very small and the protective benefit significantly outweighs the risk.

Bottom Line

Sensodyne Pronamel is a well-evidenced product. It contains sodium fluoride (1.15 mg/g) and potassium nitrate for sensitivity - a legitimate, clinically proven formulation.
Dente91 Enamel Pro has real ingredients (nano-hydroxyapatite, xylitol, lactoferrin) with some scientific backing, but its claim of being "superior" to fluoride toothpaste for tooth longevity is not supported by the current body of evidence.
Nano-hydroxyapatite is a reasonable choice if you specifically want to avoid fluoride (for personal preference), but switching away from a proven fluoride toothpaste to an unproven fluoride-free alternative on your dentist friend's recommendation is not justified by the science at this time.
If you are not at high cavity risk and your Pronamel is working for you, there is no evidence-based reason to switch.

What if I do this? I use Pronamel Sensodyne toothpaste in the morning and Dente 91 enamel pro toothpaste at night. Will it cause me negative effects for my teeth in the long run? Also for my mouth in the long run?

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Here is a thorough, honest answer to your question:

Short Answer: No, This Will Not Harm You

Using Sensodyne Pronamel in the morning and Dente91 Enamel Pro at night is not a harmful combination. There are no known negative interactions between these two products, and the approach actually has some logic behind it. Here is the full breakdown:

Why This Combination Is Safe

No Chemical Conflict Between the Two Products

The active ingredients do not interfere with each other because you are using them at separate times - not simultaneously. Pronamel's fluoride and Dente91's nano-hydroxyapatite never mix in your mouth at the same time, so there is no interaction concern.

You Retain the Core Benefit of Fluoride

By using Pronamel in the morning, you still get a full dose of fluoride every day. This is the most important thing - you are not abandoning fluoride protection entirely. Twice-daily fluoride is the gold standard, but once-daily is meaningfully protective, especially if you follow the "spit, don't rinse" approach discussed earlier.

The Night Brushing Is Actually the More Important One

Here is an interesting nuance: nighttime brushing is considered more protective than morning brushing, because saliva flow drops significantly during sleep, removing the natural clearance mechanism that washes away acids and bacteria during the day. This means the toothpaste you use at night has the longest contact time with your teeth (6-8 hours).

From a pure cavity-prevention standpoint, it would be slightly better to use your fluoride toothpaste at night and the Dente91 in the morning - the reverse of what you proposed. That said, the difference is modest if you are not at high cavity risk.

What Each Product Contributes

Time	Product	What It Does
Morning	Sensodyne Pronamel	Fluoride remineralizes enamel, potassium nitrate manages sensitivity, fluorapatite formation strengthens enamel
Night	Dente91 Enamel Pro	Nano-hydroxyapatite deposits calcium/phosphate into micro-defects in enamel, xylitol suppresses Streptococcus mutans (cavity-causing bacteria), lactoferrin has anti-inflammatory and mild antibacterial effects

The Dente91 ingredients are all well-tolerated:

Nano-hydroxyapatite - biocompatible, non-toxic, safe for long-term use
Xylitol - genuinely beneficial; reduces cavity-causing bacteria, safe for adults at toothpaste amounts
Lactoferrin - a naturally occurring milk protein with antimicrobial and anti-inflammatory properties; safe and gentle

Long-Term Outlook for Your Teeth

Positive effects you can expect:

Continued enamel protection and remineralization from the fluoride (morning)
Additional mineral deposition from nHA (night)
Bacterial suppression from xylitol (night)
Sensitivity management from potassium nitrate (morning)

Any risks?

No negative long-term effects are known from alternating these two products
The only theoretical concern is that on the nights you use Dente91, you get no fluoride - but since you are getting fluoride every morning, this is not a meaningful gap for a healthy adult who is not at high cavity risk
If you ever have active cavities or are told by a dentist you are at high caries risk, switching to fluoride for both sessions would be the safer call

Long-Term Outlook for Your Mouth (Beyond Teeth)

Gums: Both products are gentle. Lactoferrin in Dente91 may actually be mildly beneficial for gum health by reducing inflammation.
Oral microbiome: Xylitol selectively targets harmful bacteria (S. mutans) without broadly wiping out the microbiome - this is actually a gentler approach than some antibacterial toothpastes.
Mucosa (cheek/tongue lining): No irritants or harsh chemicals in either product at levels that would cause mucosal problems long-term.
Systemic effects: The fluoride dose from one daily brushing session (if you spit properly) is well within safe limits for adults.

Practical Suggestion

If you want to slightly optimize what you are already planning, swap them around:

Morning - Dente91 (nHA + xylitol + lactoferrin)
Night - Sensodyne Pronamel (fluoride stays on your teeth for 6-8 hours while you sleep - maximum contact time)

This gives fluoride the longest possible contact time overnight and lets the nHA work during the day. But honestly, either order is fine and safe. You are doing better than most people by thinking carefully about this at all.

I mean I have a diagnosis and the doctor has given me a mouth guard. Two years back, the mouth guard that I received was very thin and it got spoiled in just six months. But later, the doctor gave me a thicker mouth guard. This one is pretty thick. But when I consulted a friend of mine who is also a dentist, he said that this thick mouth guard is dangerous over the long time because it will affect the temporomandibular joint and if something happens to the temporomandibular joint, there is no cure. He said, asked me to revert back to the smaller size, the thinner mouth guard, and use it only at night.

Reading File

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Reading Article

This is excellent - I now have very specific, directly relevant research to answer your question thoroughly. Here it is:

First: What Is Your Diagnosis Likely To Be?

You have been given an occlusal splint (mouth guard) by a dentist. The most common diagnoses for which these are prescribed are:

Bruxism (teeth grinding/clenching, usually at night)
Temporomandibular disorder (TMD) - pain and dysfunction of the jaw joint and surrounding muscles
TMJ disc displacement - where the articular disc inside the jaw joint is displaced, causing clicking, pain, or reduced mouth opening

The fact that you were given a thicker guard after the thin one wore out suggests your grinding forces are significant, which is actually a reason a dentist might deliberately prescribe a thicker appliance.

What the Research Actually Says About Splint Thickness

Your friend's concern is partially valid but significantly overstated. Here is the nuanced picture from recent research:

Study 1 - Bilir & Kurt, Int J Prosthodont, 2022 (PMID 35507529)

This clinical study directly compared 2mm vs 4mm stabilization splints in TMD patients over 6 months. Key findings:

Both the thinner (2mm) and thicker (4mm) splints effectively reduced muscle pain and jaw clicking
The thicker 4mm splint actually showed better improvement in TMJ sounds (clicking) in patients with combined muscle and joint problems
The thinner 2mm splint was associated with a reduction in maximum mouth opening at 6 months - a potentially concerning finding
Neither caused irreversible joint damage over the study period

Study 2 - Topdag et al., BMC Oral Health, 2026 (PMID 42098687) - Published just last month

This is the most current evidence. A finite element analysis comparing 3mm and 5mm splints found:

Splints of all thicknesses reduced peak stress on the TMJ compared to wearing no splint at all
The key clinical conclusion: "Splint selection should consider the main treatment goal, with attention to using the minimal effective thickness"
Thicker splints were not found to cause damage - but the principle of using the least thickness needed to achieve the goal was endorsed

Study 3 - Hegab et al., RCT, Oral Surg Oral Med Oral Pathol, 2018 (PMID 29146196)

An RCT using MRI to determine optimal splint thickness for TMJ disc displacement found:

For disc displacement with reduction (clicking jaw): 4mm thickness was recommended
For disc displacement without reduction (locked jaw): 6mm thickness was recommended
Thicker was actually better for more severe disc problems - the opposite of what your friend suggested

The Real Concern: Type of Splint Matters More Than Thickness Alone

The TMJ Association makes an important distinction your dentist friend may be conflating:

Splint Type	Risk Level	Notes
Stabilization splint (flat plane / Michigan splint)	Low risk	The standard type - relaxes muscles, protects teeth. Both thin and thick versions are generally safe
Repositioning splint	Higher risk	Moves the jaw to a new position. Prolonged use (>6 weeks) can cause permanent bite changes and joint damage

The serious TMJ risks your friend is describing are real - but they are specifically associated with repositioning/anterior repositioning splints used long-term, not with standard flat stabilization splints regardless of thickness. If your thick guard is a stabilization splint (flat biting surface), the risk he described is much lower.

The "No Cure for TMJ Damage" Claim

Your friend is right that severe, end-stage TMJ damage (like condylar resorption or advanced osteoarthritis) can be very difficult to reverse and may require surgery. This is a valid general warning. However:

It applies primarily to untreated bruxism (where no splint is used and grinding destroys teeth and the joint) or to wrongly used repositioning splints
A properly fitted stabilization splint, whether thin or thick, protects the TMJ rather than harming it - it absorbs the forces that would otherwise be transmitted directly to the joint surfaces
The risk of harm from a well-prescribed thick stabilization splint is much lower than the risk of harm from removing it and grinding unprotected

What You Should Actually Do

Your friend's advice to switch back to a thin splint is not well-supported by the current evidence and may actually be counterproductive, especially if:

Your grinding forces are strong enough to have destroyed a thin splint in 6 months
Your prescribing dentist had a specific clinical reason for the thicker design

The right course of action:

Do not self-modify your treatment based on one friend's opinion, especially if your prescribing dentist had a specific reason for the thicker guard
Ask your prescribing dentist directly: "What type of splint is this - stabilization or repositioning? Why did you choose this thickness?" A good dentist will explain the rationale
If you are genuinely concerned, get a second opinion from a TMJ specialist (oral and maxillofacial surgeon or a prosthodontist with TMD training) - not just a general dentist
Watch for warning signs that the splint may be causing problems: changes in your bite when you remove it in the morning, new jaw pain, clicking that is getting worse, or teeth feeling like they no longer fit together properly. Report these immediately
The fact that your thin splint wore through in 6 months is actually an important data point - it shows the magnitude of your grinding forces. A thin splint replaced by an equally thin one may simply fail again and leave you unprotected

Bottom Line

Your friend's concern is not baseless - splint type and fit do matter for TMJ health. But his conclusion (switch to the thinner one, it's dangerous) is not what the current evidence supports. Thick stabilization splints have been shown in multiple studies to be safe and effective. The "no cure for TMJ damage" warning is real but applies to the wrong scenario here. Talk to your prescribing dentist before making any changes.

It was for bruxism

That actually makes your situation much clearer - and it significantly changes the risk calculus in your favor. Here is the focused answer:

Bruxism + Thick Splint: Your Friend's Advice Is Largely Wrong

For bruxism specifically, the thick splint your dentist prescribed makes very good clinical sense, and the concern about TMJ damage from it is largely misplaced. Here is why:

The Core Logic Is Reversed

In bruxism, the danger to your TMJ comes from the grinding forces themselves - not from the splint protecting you against them. When you grind at night:

Peak forces on the TMJ can reach several hundred Newtons - far higher than normal chewing
These forces are transmitted directly to the articular disc and condylar cartilage
Over years, this causes disc displacement, condylar erosion, and ultimately the irreversible joint damage your friend warned you about

A splint - especially a thicker one - sits between your teeth and absorbs and distributes those forces before they reach the joint. Removing the thick splint and replacing it with a thin one that you already know will fail in 6 months leaves your teeth and joint partially or fully unprotected for stretches of time.

Why Your Dentist Gave You a Thicker One

The fact that you ground through a thin splint in 6 months tells your dentist something important: you are a severe bruxer. The grinding force you generate is high enough to physically destroy the appliance material. Prescribing a thicker splint is the standard clinical response to this - it is not dangerous, it is appropriate escalation of protection.

The TMJ Risk That Is Real for Bruxism

The genuine long-term TMJ risks in bruxism are:

Not wearing a splint at all - unprotected grinding causes cumulative joint damage
Wearing a splint that is too soft or too thin and wears through, leaving gaps in protection
A poorly fitted splint that creates uneven bite contacts and puts asymmetric load on one joint

A well-fitted, thick flat-plane stabilization splint (which is the standard for bruxism) does not cause any of these problems. It is the treatment, not the threat.

What About the "Repositioning Splint" Risk?

The serious long-term TMJ risk your friend may be thinking of applies to anterior repositioning splints - these protrude the jaw forward to recapture a displaced disc. Used for months or years, these CAN permanently alter the bite and stress the joint. But these are not prescribed for bruxism. Bruxism splints are flat-plane stabilization appliances. They do not reposition the jaw. They just provide a hard, flat surface to grind against.

Practical Summary

Scenario	TMJ Risk
Keep the thick splint, wear it nightly	Low - this is what it was designed for
Switch to thin splint (friend's advice)	Moderate - will likely fail again, leaving you unprotected
Stop wearing any splint	High - bruxism forces transmit directly to joint and teeth
Thick repositioning splint long-term	High - but this is NOT what you have

Your prescribing dentist made the right call. A thick stabilization splint for a severe bruxer is standard, evidence-based practice. Your dentist friend's advice - however well-intentioned - is based on a risk that does not apply to your situation. Keep wearing the thick one, wear it every night, and get it checked periodically for wear. That is the best thing you can do for your TMJ long-term.

What my friend is saying that this sticker guard will actually prevent the teeth from, that is prevent the normal resting position of the temperament dipolar joint while sleeping, because the teeth will be further away from each other, the upper and the lower teeth. So that for a long period of time can cause TMJ issues, which can become very serious.

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Now I can give you a precise, anatomically grounded answer to this specific argument.

Your Friend's Argument - The Anatomy Behind It

Your friend is raising a concept called occlusal vertical dimension (OVD) and freeway space (interocclusal clearance). This is real anatomy, worth understanding properly.

Normal Jaw Anatomy at Rest

When your jaw is in its natural resting position - not biting, not talking, just relaxed - there is a small gap between your upper and lower teeth of about 2-3mm. This is called the freeway space (also called interocclusal distance). In this position:

The jaw muscles are at their minimal tension resting length
The TMJ condyle sits in a relaxed, unstrained position in the socket
There is no active muscle effort required to hold the jaw

This is the position your jaw naturally finds during sleep when not grinding.

Your Friend's Logic

A thick splint increases the distance between your upper and lower teeth - it increases the vertical dimension. His argument is:

"If the vertical dimension is increased beyond the natural freeway space for 6-8 hours every night, the jaw muscles must work harder to hold that position, the condyle is forced into an abnormal position in the joint, and over years this causes irreversible TMJ damage."

This is anatomically coherent reasoning. It is not nonsense. The question is whether it actually plays out clinically.

What the Evidence Shows

The Historical Context: This Was Already Tested and Found Wanting

This exact concern was the basis of "Costen's syndrome" - a theory from the 1930s-50s that altered vertical dimension caused TMJ problems. Researchers spent decades studying it. The conclusion, cited in multiple reviews:

"No scientifically compelling evidence was provided to support these claims... Schwartz reported his work of 10 years with 2500 TMJ patients and observed that symptoms were unable to be related to bite closure changes."

The feared cascade - muscle overload, condylar strain, bone resorption from altered vertical dimension in a splint - was not replicated in subsequent longitudinal research.

Why the Fear Doesn't Apply to a Night Splint

Your friend's argument would be valid if you were permanently altering your bite - for example, building up crowns or veneers to raise your vertical dimension forever. That is an irreversible change and requires very careful measurement. But a night splint is removable and temporary:

You wear it for 6-8 hours
You remove it in the morning
Your jaw immediately returns to its natural resting position
The muscles and joint spend 16 hours per day in their normal position

The 6-8 hours of slightly increased vertical dimension with the splint in place is not the same as permanently locking your jaw at that height. The joint and muscles reset every morning.

What the Manns et al. RCT (PMID 6580439) Found

This randomized controlled trial specifically studied different vertical dimensions in splints for TMJ/muscle pain. It found that splints at a moderately increased vertical dimension actually produced better muscle relaxation than splints at minimal vertical opening. The muscles did not get more strained - they got less strained with a bit of vertical opening. This is because some degree of jaw opening decompresses the TMJ condyle slightly, reducing joint loading.

The 2026 Finite Element Study (PMID 42098687)

As noted before, the most recent evidence (published May 2026) confirmed that thicker splints reduced peak stress on the TMJ structures compared to thinner ones and compared to no splint. If increased vertical dimension were damaging the joint, you would expect to see higher stress with thicker splints. The opposite was found.

Where Your Friend's Concern IS Valid

There is one scenario where increased vertical dimension from a thick splint can genuinely cause problems:

The splint is too thick - beyond the freeway space and beyond therapeutic range. If the splint is so thick that it completely obliterates the freeway space and forces the jaw to work against it rather than rest, muscle fatigue and joint strain can result. This is why the clinical principle of "minimal effective thickness" exists. Your dentist should have measured your freeway space when designing the splint.
Uneven contact points on the splint. If the splint is not properly adjusted and certain teeth hit harder than others, it creates asymmetric loading on one TMJ - which is more problematic than increased vertical dimension per se.
Sleep apnea. There is a real, separate concern: the American College of Prosthodontists has noted that increasing vertical dimension with a maxillary night guard (without mandibular protrusion) can aggravate obstructive sleep apnea in some patients. If you snore, have interrupted sleep, or have been told you may have sleep apnea, this is worth raising with your doctor.

The Key Question to Ask Your Dentist

Rather than simply switching to a thinner guard based on your friend's advice, ask your prescribing dentist:

"Did you measure my freeway space when making this splint, and is the splint thickness within that range?"

A well-made bruxism splint is designed to sit within the freeway space - it takes up some of that 2-3mm gap but does not exceed it excessively. If your dentist did this correctly, your friend's concern, while anatomically logical in theory, does not apply to your specific situation.

Summary

Your Friend's Claim	Verdict
Thick splint increases vertical dimension	True - that is how splints work
This prevents normal TMJ resting position	Partially true during wear; false overall since you remove it every morning
Long-term this causes irreversible TMJ damage	Not supported by longitudinal evidence for properly fitted removable splints
Switch to a thin splint	Risky for a severe bruxer - you already destroyed a thin one in 6 months
The concern about vertical dimension is completely irrelevant	Also wrong - it is a real principle that your dentist should have accounted for in the design

The bottom line: your friend understands the anatomy correctly but is applying a risk that is relevant to permanent dental changes to a removable appliance - and the evidence does not support that leap.

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