New Clinical Trial Compares Treatments for Cavities in Baby Teeth

A new Hall Technique clinical trial tested three ways to manage two-surface dentin caries in primary molars. Hall crowns had no failures at 18 months. Compomer restorations succeeded in 90.9% of teeth. Ammonia-free silver fluoride succeeded in 63.6%, and three in four of its failures were major. Pain and chair time pointed in a different direction.

TL;DR

• Zero Hall failures in 55 teeth still fits a true failure rate of up to about 6%.

• Silver fluoride arrested 80% of lesions at 6 months and lost much of that effect by 18 months.

• Most silver fluoride failures involved irreversible pulpitis or abscess.

• The trial excluded uncooperative children, the group where Hall crowns and silver fluoride matter most.

Hall Technique Achieves 100% Success in 18-Month Clinical Trial

The study appeared in BMC Oral Health on October 12, 2026. All 55 Hall-treated molars stayed free of clinical and radiographic failure. Compomer restorations succeeded in 50 teeth, and silver fluoride in 35.

A 100% Hall Technique success rate needs careful reading. Zero events in 55 teeth is still statistically compatible with a true failure rate of up to about 6%. The direction of the result matches systematic reviews of Hall crowns in primary molars.

Success meant the tooth had neither a minor nor a major failure. Minor failures covered caries progression, restoration loss, and secondary caries. Major failures covered pulpal disease that required further intervention.

Overall group differences were significant (p < 0.001). At 18 months, pairwise testing separated the Hall Technique from silver fluoride only. Hall crowns and compomer restorations did not differ significantly. A 9-point difference across 55 teeth cannot establish superiority.

How Researchers Compared the Three Cavity Treatments

The Erciyes University team in Türkiye used a three-arm randomized split-mouth design. Each child received all three treatments on separate primary molars. The design removes patient-level confounders such as diet, saliva, brushing, and caregiver habits. These factors drive outcomes in primary molar caries treatment.

Split-mouth trials carry one known weakness: treatments can affect other quadrants. Here, the silver fluoride arm included 22,600 ppm fluoride varnish every six months. That varnish likely reached other study teeth. Any carry-over benefit would shrink the differences between arms.

Sixty children aged 4–8 years contributed 180 teeth. At 18 months, 55 children and 165 teeth remained. All lesions were active, occluso-proximal, and ICDAS 3–5, with dentin involvement limited to the outer or middle third. These lesions are well past the early signs of cavities in baby teeth that parents notice. They match the textbook Hall indication.

Hall Technique

The Hall Technique manages caries as a biofilm disease. A cemented crown cuts the lesion off from dietary sugar, and the trapped biofilm becomes inactive. Full coverage also protects the proximal margin, where Class II restorations commonly fail. Each Hall Technique stainless steel crown was cemented with glass ionomer. The protocol used no anesthesia, caries removal, tooth preparation, crimping, or contouring. Orthodontic separators opened tight contacts over 3–5 days, and up to 2 mm of occlusal discrepancy was accepted.

Ammonia-Free Silver Fluoride

The trial used Riva Star Aqua, a water-based 38% silver fluoride (AgF) without ammonia. These results are not data on silver diamine fluoride (SDF). In SDF, ammonia keeps silver in a stable complex at high pH. Removing it may reduce how much silver is available to penetrate dentin. The protocol added potassium iodide to limit black staining. Potassium iodide binds free silver as silver iodide, and earlier trials linked this step to lower arrest rates. Fluoride varnish followed each application, and the full protocol was repeated every six months.

Conventional Restorations

The control arm used complete caries removal, a universal adhesive, and a single compomer increment. Local anesthesia was given when needed. Isolation relied on cotton rolls and suction, without rubber dam. AAPD restorative guidance cites meta-analytic evidence that rubber dam extends restoration life. The arm's failures were restoration loss and secondary caries, and both depend on isolation quality. Complete excavation also departs from current cavity treatment practice, which favors selective removal near the pulp.

Which Treatment Performed Best After 18 Months?

Hall crowns led at every recall. The more useful pattern lies in how each treatment failed.

Silver fluoride followed a recognizable arc. About 80% of lesions were inactive at 6 months, and activity then returned in a subset. Minor failures peaked at 21.8% at 12 months, all from progression. By 18 months, 27.3% of AgF teeth had major failures, mostly irreversible pulpitis or abscess.

Proximal lesions are a hard target for non-restorative care. Plaque stagnates below the contact point, where a toothbrush rarely reaches. Arrest depends on a cleanable lesion surface, and this site resists cleaning.

No compomer-restored tooth developed pulpal disease. In an exploratory model, lower second primary molars and higher ICDAS scores failed sooner. These molars combine broad contacts, difficult isolation, and the longest remaining lifespan.

How Did the Treatments Compare for Pain and Appointment Time?

Children rated pain on a six-point faces scale, and the dentist scored behavior on the Frankl scale. A stopwatch timed each visit.

Median pain was zero in every arm. Silver fluoride ranked lower than Hall crowns (p = 0.005). The Hall score recorded the worse of two moments – separator placement or crown seating. Separators are often the least comfortable step of the Hall sequence. Behavior scores did not differ between arms.

Hall crowns and silver fluoride each took a median of 5 minutes. Compomer restorations took 15 minutes, which is short for an anesthetized Class II restoration. Rubber dam would have added time. Chair time shapes cooperation, and durability depends on the seal.

The low procedural pain of silver fluoride needs context. One in four AgF teeth later developed a major failure. For many families, a later abscess outweighs a painless first visit.

Hall crowns raised occlusal vertical dimension by a median of about 1 mm. It returned near baseline within a month, consistent with the Dahl effect. Parents should expect the bite to feel high for a few weeks.

What Do the Results Mean for Pediatric Treatment Planning?

The trial informs a sequence of clinical questions.

Pulp status comes first. Hall crowns require a healthy pulp and sound dentin between the lesion and the pulp. Lesion extent comes next. AAPD guidance favors stainless steel crowns for large or multi-surface primary molar lesions in high-risk children. Small occlusal lesions in a cooperative child rarely need full coverage. Not every primary molar cavity requires a stainless steel crown.

Remaining lifespan changes the calculation. A first primary molar in an 8-year-old may exfoliate within two years. A lower second molar in a 4-year-old must function for six years or more.

Recall reliability governs silver fluoride in primary teeth. Families who miss six-month visits are poor candidates for long-term arrest. AgF and SDF still help to stabilize multiple lesions before definitive care.

Baby teeth cavity treatment decisions belong in an individualized dental treatment plan. Isolation and cooperation then guide the choice of dental materials. The trial adds data to minimally invasive pediatric dentistry. Parents researching treating cavities in baby teeth at home should know that dentin lesions need professional care.

What Are the Study's Limitations?

Each limitation narrows a specific clinical conclusion.

• Only cooperative children (Frankl 3–4) qualified. The children who benefit most from avoiding drills and anesthesia were excluded.

• Lesions in the inner third of dentin were excluded. The trial cannot guide Hall use where pulpal risk is highest.

• One specialist worked in one center. Outcomes may differ with other operators and in US general practice.

• Outcome scoring differed by arm. Open AgF lesions were rescored with ICDAS, and restorations were scored against failure criteria.

• Follow-up stopped at 18 months, years before most second molars exfoliate.

The trial was registered retrospectively in February 2026, after enrollment began. The Cox model did not account for each child contributing three teeth. Two questions now matter most for practice. Would 38% SDF without potassium iodide arrest proximal lesions more reliably? Would Hall crowns keep their advantage over rubber-dam restorations until exfoliation?

Bottom Line

Within this trial's narrow indication, Hall crowns gave the most predictable 18-month outcome. Compomer restorations performed close behind, with no significant difference. Ammonia-free silver fluoride with potassium iodide arrested lesions early, then lost ground on proximal surfaces. Its low procedural pain came with a high later rate of pulpal failure. Treatment choice still starts with pulp status, lesion depth, cooperation, and remaining tooth lifespan.