Fluoride and sealants, the treatments that prevent treatment.

The pits and fissures on the biting surfaces of the back teeth are highly vulnerable to decay. They are narrow, deep, and impossible to clean with a toothbrush bristle, which is wider than the fissure itself. Food debris and bacteria pack into these grooves and produce the acid that dissolves enamel. A pit-and-fissure sealant is a thin layer of flowable resin or glass-ionomer cement that is applied to these surfaces immediately after the tooth erupts, filling the grooves and creating a smooth, cleanable surface where bacteria can no longer accumulate. The tooth is not drilled, not anaesthetised, and not altered; it is simply protected.

The Cochrane systematic review on pit-and-fissure sealants for permanent teeth rests on unusually solid evidence. Ahovuo-Saloranta and colleagues pooled the randomised trials and found, with moderate-quality evidence, that resin-based sealants reduced decay on children's permanent molars by between 11 and 51 percentage points at two years compared with no sealant, with a similar benefit up to four years ^[1]. A systematic review for the American Dental Association and the American Academy of Pediatric Dentistry by Wright and colleagues found that sealed molars still had far lower odds of decay after seven or more years ^[2]. For baby teeth the picture is less certain: a 2022 Cochrane review rated the evidence low to very low and could not establish a benefit ^[3]. Where the evidence is strong, the message is consistent: sealants help where the grooves are deep, on permanent molars, placed soon after the tooth comes through.

Fluoride works at the enamel surface by replacing hydroxyl ions in the hydroxyapatite crystal lattice with fluoride ions, forming fluorapatite, a structure that is more resistant to acid dissolution and that promotes the remineralisation of early enamel lesions that have not yet become cavities. Professional fluoride application, usually as a 5% sodium fluoride varnish painted directly onto the teeth, delivers a high concentration of fluoride to the enamel surface in a single visit, supplementing the daily low-concentration exposure from fluoride toothpaste and, where available, fluoridated water.

The Cochrane review of fluoride toothpastes by Walsh and colleagues found that, in adults of all ages, a standard 1000 or 1100 ppm fluoride toothpaste reduced new decay compared with a non-fluoride paste, and that in children and adolescents the benefit grew with concentration up to 1450 or 1500 ppm ^[4]. For lesions that have already started, the ADA network meta-analysis by Urquhart and colleagues ranked the options that avoid drilling differently for each surface: a sealant combined with fluoride varnish came first for early lesions on biting surfaces, resin infiltration with varnish between the teeth, and a 5,000 ppm fluoride toothpaste or gel for decay on exposed roots ^[5]. For adults, the tools used most here are fluoride varnish at recall visits and a higher-strength fluoride toothpaste when your caries risk calls for it. For children, Dr. Khalid assesses and explains what the evidence supports, and their sealants and fluoride are kept in trusted hands.

Not every patient needs every preventive intervention. For a child with newly erupted permanent molars and deep fissures, the evidence favours sealants placed as soon as the tooth is fully erupted and can be kept dry long enough for the resin to bond. An adult with early white-spot enamel lesions around orthodontic brackets benefits from high-concentration fluoride varnish and remineralisation protocols. A patient with low caries risk, good home care, and no active lesions may need nothing more than a fluoride toothpaste and a risk-appropriate recall interval. The decision is based on the caries risk assessment we perform at your comprehensive examination: the same data that determines your recall interval also determines which preventive tools are indicated.

The case for prevention is easiest to see in what it saves the tooth. Neither a sealant nor fluoride varnish removes any tooth structure, so if prevention works, the tooth never enters the restorative cycle at all. Once a tooth has its first filling, replacements tend to grow: in a study of 1,337 recommendations to replace fillings in back teeth, 70 percent would have increased the number of restored surfaces ^[6]. Each step in that cycle, from filling to larger filling, onlay and crown, leaves less natural tooth behind. Breaking the cycle before it starts, by sealing a vulnerable groove or remineralising an early lesion before it becomes a cavity, is the approach that leaves the tooth intact. That is what conservative dentistry means, and these two treatments express it plainly.