Dental implants in Jeju: do you need to replace the rearmost molar?
Replacing a missing second molar is recommended when its absence leaves chewing function or posterior support inadequate and the replacement can make functional contact with the opposing tooth. Even when eating feels comfortable, a weakened first molar and limited support on the other side can increase the need for restoration.
If the first molar is healthy, the bite is stable on both sides and there is no ongoing damage, monitoring may be appropriate. Cracks, inflammation and repeated fractures require diagnosis and treatment of the remaining teeth first, followed by reassessment of any need for extra support.
Key points
- Restore when missing posterior support limits function and the replacement can contact the opposing tooth.
- Monitor when the first molar, its gum support and the bite on both sides remain stable.
- Treat cracks, inflammation, repeated fractures or loose screws first; reassess support afterwards.
When is replacement recommended, and when can we monitor?
The second molar is the large back tooth immediately in front of the wisdom tooth. The first molar is the large tooth in front of it. The decision combines comfort during eating with the condition of the remaining teeth and their functional contacts.
The table below connects examination findings with treatment choices. Replacement assumes that surgery is feasible, the new tooth can function against an opposing tooth, and cleaning and maintenance are manageable.
| Finding | Treatment direction |
|---|---|
| Missing second molar leaves chewing function or posterior support inadequate | Recommend replacement if the new tooth can make functional contact. |
| Weak first molar, clenching or repeated damage, and limited support on the other side | Treat the remaining tooth and loading problems first. Recommend replacement if support remains inadequate. |
| Stable first-molar structure, gum support and bilateral bite, without ongoing damage | The second molar can be monitored without immediate replacement. |
| First-molar pain, cracks or periodontitis, or repeatedly loose implant screws | Diagnose and treat the cause first. A second-molar implant alone is not the solution. |
| No usable opposing tooth, so the new tooth cannot contact it | Plan treatment of the opposing tooth first; defer an isolated second-molar implant plan. |
Replace the tooth when chewing function or posterior support is inadequate
When chewing is difficult on the side without the second molar and remains inadequate after other tooth pain or gum problems are treated, replacement can be helpful. The aim is to create useful contact with the opposing tooth and restore chewing function.
If a large restoration or lost tooth structure has weakened the first molar and missing molars on the other side also limit support, comfort alone is not a sufficient reason to monitor. After treating the first molar, recommend second-molar restoration if additional functional support is still needed.[6,10]
- Missing teeth limit food intake despite treatment of other causes.
- Remaining posterior support is insufficient and more functional contacts are needed.
- The restored second molar can contact its opposing tooth and share load.
- Surgery, cleaning and maintenance are manageable.
Monitoring is reasonable when the remaining teeth and bite are stable
Monitoring requires more than comfortable eating. First-molar structure and periodontal support, and functional contacts on both sides, should be stable. There should be no new cracks, repeated fractures or progressive tooth movement; clenching and grinding also need assessment.
With these conditions confirmed, immediate replacement may be deferred. Monitoring can be especially reasonable when replacement would require substantial surgery and present function is adequate. The EFP guideline also considers non-replacement when function and stability are sufficient.[6]
- No first-molar decay, crack, restoration damage or progressive periodontal problem needing treatment.
- Functional contacts on both sides and the ability to chew necessary foods.
- No ongoing repeated tooth or restoration fractures or screw loosening.
- Stable opposing-tooth position and restorative space, with regular comparison at reviews.
New pain, cracks, repeated fractures, screw loosening, declining function or overeruption of the opposing tooth require reassessment rather than continuing the same monitoring plan.
How does loading of the first molar affect the decision?
Missing a second molar can change load sharing among the remaining teeth. In a model study under strong biting, the load on the first-molar implant was lower when both molars were replaced than when only the first molar was replaced.[7]
When structural weakness, strong clenching, repeated damage and limited support on the other side occur together, managing load and providing adequate support become important goals. If posterior support remains insufficient after the causes are addressed, second-molar replacement may be preferable. The new tooth must make functional contact to share load.
| Remaining molar condition | How it informs treatment |
|---|---|
| Healthy natural first molar and adequate opposite-side support | Monitoring is possible without damage or functional deficiency. |
| First molar with a large restoration or lost tooth structure | Protect the structure with appropriate restoration, then assess additional support. |
| Strong clenching, repeated damage and limited posterior support | Treat loading and damage causes, then replace the second molar if support remains inadequate. |
| Repeated screw loosening or restoration fracture at a first-molar implant | Correct connection, restoration, bite and loading problems first; reassess any remaining support deficit. |
Load distribution is one clinical reason for recommending replacement. Direct long-term clinical evidence for how much a second-molar implant prevents first-molar fracture remains limited.
Treat first-molar cracks or inflammation first
Pain on biting, a suspected crack, an unsatisfactory restoration or periodontitis requires assessment of whether the first molar can be preserved and what treatment it needs. Assess remaining tooth structure, cusps, crack extent, periodontal support and mobility, then provide appropriate restorative or periodontal care.[10,11]
If the first molar is an implant, investigate repeated screw loosening or restoration fractures through the connection, restoration design, bite and loading habits. Examine surrounding inflammation separately. After correcting the problems, assess whether posterior support is still inadequate.
Clenching or grinding alone does not establish a need for a second-molar implant. Use the history and damage record to guide habit management and protective measures first. Consider additional restoration when compromised remaining teeth and inadequate support are also present.[9,12]
The new tooth needs a functional opposing contact
Replacing the second molar does not immediately provide chewing function if the opposing tooth is absent or has a poor outlook. First establish its treatment or replacement plan so that both teeth can function together.
If overeruption of the opposing tooth is reducing restorative space, continued observation alone is insufficient. Decide how to restore space and the bite alongside second-molar replacement. Treatment of the opposing tooth may be needed in addition to implant placement.[2]
Weigh the functional benefit against the surgical burden
When current function and remaining teeth are stable but replacement requires extensive grafting or difficult surgery, monitoring may be more reasonable. When posterior support is inadequate and restoration offers substantial benefit, compare the necessary surgical methods and burden.
Assess the lower-jaw nerve canal, upper-jaw sinus, available bone, access for instruments and cleaning. CT helps plan surgery; the need for replacement also depends on oral examination and functional assessment.[3]
- An isolated missing second molar in an otherwise largely natural dentition differs from full-arch implant treatment. Full-arch decisions depend on implant positions, the connected restoration’s length and the overall support structure.
A decision to monitor an isolated second-molar space should not be applied directly to full-arch restoration length or posterior extensions.
How does research inform these decisions?
A 2025 prospective study of 32 patients with unilateral molar loss found greater improvement in bite force and chewing function when both molars were replaced with implants than when only the first molar was replaced. Quality-of-life improvements were similar. Feeling comfortable does not necessarily mean that additional replacement offers no functional benefit.[4]
A ten-year shortened-dental-arch study and an observational study involving second-molar loss show that selected patients with adequate function can use a reduced dentition.[1,5] Adaptation also affects load sharing among natural teeth.[8] The EFP guideline considers non-replacement when contacts are sufficient and suggests implant restorations when additional occlusal units are needed.[6]
These criteria combine research with clinical assessment. The studies involve different populations and treatment comparisons; the EFP guideline applies to patients with stage IV periodontitis.
Putting the second-molar decision together
Benefits of replacement: Additional posterior contacts can improve chewing and allow more teeth to share load. For patients with inadequate function, replacement can improve food choices and chewing ability.[4,7]
When replacement is recommended: The missing second molar leaves function or posterior support inadequate, and a replacement can make functional contact. If a weakened first molar, clenching, repeated damage and limited opposite-side support occur together, treat the causes and assess whether extra support is still needed.
When to monitor: First-molar structure and periodontal support are stable, necessary foods can be chewed on both sides, and there are no repeated fractures or progressive tooth movements. The decision requires regular comparison of teeth and contacts rather than comfort alone.
If first-molar support is lost during monitoring: The basis for the original decision has changed. Preserve the first molar and restore its support when possible. If it cannot be preserved or is already missing, first assess the need to replace it and reconsider whether to restore the second molar as well. Recommend molar restoration when the remaining teeth cannot provide adequate chewing and posterior support. Decide the scope from opposing contacts and the feasibility of surgery and maintenance.[6,10]
Related articles
References
- [1] Reissmann DR, et al. Impact of shortened dental arch on oral health-related quality of life over a period of 10 years — A randomized controlled trial. J Dent. 2019;80:55–62.
- [2] Craddock HL, Youngson CC, Manogue M, Blance A. Occlusal Changes Following Posterior Tooth Loss in Adults. Part 1: A Study of Clinical Parameters Associated with the Extent and Type of Supraeruption in Unopposed Posterior Teeth. J Prosthodont. 2007;16:485–494.
- [3] Kim MJ, Chang HJ, Ahn KM. Survival Rate of Single Implant When Replacing the Mandibular Second Molars: Importance of Implant Length. J Implantol Appl Sci. 2022;26(4):222–233.
- [4] Sakata A, et al. Function, Quality of Life, and Food Intake in Patients Without Second Molar Implants: A Prospective Cohort Study. Clin Implant Dent Relat Res. 2025;27(1):e70006.
- [5] Yokoi T, et al. Association between the treatment choice of implant-supported fixed partial dentures and oral health-related quality of life in patients with a shortened dental arch: A preliminary observational study. J Dent Sci. 2024;19(3):1667–1672.
- [6] Herrera D, et al. Treatment of stage IV periodontitis: The EFP S3 level clinical practice guideline. J Clin Periodontol. 2022;49(Suppl 24):4–71.
- [7] Yoshitani M, Takayama Y, Yokoyama A. Significance of mandibular molar replacement with a dental implant: a theoretical study with nonlinear finite element analysis. Int J Implant Dent. 2018;4:4.
- [8] Hattori Y, et al. Occlusal and TMJ Loads in Subjects with Experimentally Shortened Dental Arches. J Dent Res. 2003;82(7):532–536.
- [9] Manfredini D, et al. Standardised Tool for the Assessment of Bruxism. J Oral Rehabil. 2024;51(1):29–58.
- [10] European Society of Endodontology. European Society of Endodontology position statement: The restoration of root filled teeth. Int Endod J. 2021;54(11):1974–1981.
- [11] Ng Y-L, Mann V, Gulabivala K. A prospective study of the factors affecting outcomes of non-surgical root canal treatment: part 2: tooth survival. Int Endod J. 2011;44(7):610–625.
- [12] Chrcanovic BR, Kisch J, Albrektsson T, Wennerberg A. Bruxism and dental implant failures: a multilevel mixed effects parametric survival analysis approach. J Oral Rehabil. 2016;43(11):813–823.
This article provides general dental information. Individual diagnosis and treatment require an examination.