THE RELATIONSHIP BETWEEN VERTICAL CROWN PREPARATION AND GINGIVAL TISSUES

ABSTRACT

Vertical tooth preparation, including BOPT and VEP, has gained attention for its positive effect on marginal gingival tissues. Unlike horizontal finish lines, it creates an adaptive soft-tissue contour guided by provisional and final restorations. When the connective tissue attachment is preserved, gingival thickening, margin stability, and improved emergence profiles can occur. Histological studies confirm the ability of sulcular epithelium to reorganize, while 2–6-year clinical follow-ups show low inflammation and minimal recession. Although technique-sensitive, proper tissue management and careful cement removal make vertical preparation a biologically sound and predictable option, especially in esthetically demanding cases.

АННОТАЦИЯ

Вертикальная препаровка зубов, включая BOPT и VEP, привлекает внимание благодаря позитивному влиянию на маргинальные ткани. В отличие от горизонтальных уступов, она формирует адаптивный контур мягких тканей за счёт временной и окончательной реставрации. При сохранении соединительнотканного прикрепления возможны утолщение десны, стабилизация уровня края и улучшение emergence-профиля. Гистологические исследования подтверждают способность эпителия к реорганизации, а клинические наблюдения на 2–6 лет показывают низкое воспаление и минимальную рецессию. Несмотря на чувствительность техники, корректное выполнение делает вертикальную препаровку биологически обоснованным и предсказуемым методом в эстетической зоне.

Keywords: vertical preparation; BOPT; gingival tissues; biological width; soft-tissue stability; emergence profile.

Ключевые слова: вертикальная препаровка; BOPT; мягкие ткани; десна; биологическая ширина; реставрации; эстетика.

Introduction. Vertical crown preparation has drawn increasing interest as an alternative to traditional chamfer and shoulder designs that prioritize retention and marginal accuracy [1,2]. Growing focus on soft-tissue stability in the esthetic zone has highlighted techniques such as BOPT and VEP, which remove the fixed finish line and use the cervical contour of provisional and final restorations to guide gingival adaptation [1,5]. Studies show that vertical preparation can promote gingival thickening, margin stability, and improved emergence profiles when performed correctly [3–5], though improper subgingival instrumentation may disrupt the supra-crestal tissue attachment [2,6]. Therefore, careful tissue management and precise provisionalization are essential. The aim of this paper is to summarize current evidence on the interaction between vertical preparation and gingival tissues.

Understanding the biologic response to crown preparation begins with the concept of the supra-crestal tissue attachment, which includes the junctional epithelium and connective tissue. Its violation can lead to inflammation, recession, or pocket formation [2]. Traditional protocols therefore prefer supra- or equigingival horizontal margins, using subgingival placement mainly for esthetic reasons to reduce the risk of damaging this biologically sensitive zone [2].

Vertical preparation introduces a different approach. Instead of a fixed finish line, the cervical area becomes an adaptive zone where gingival tissues can stabilize around the emergence profile of the provisional and final restoration [1,5]. Clinical evidence shows that the gingiva is able to remodel and reposition itself when provisional crowns are properly shaped [3,4].

Histologic studies confirm that the sulcular and junctional epithelium can reattach and reorganize along smooth prosthetic surfaces as long as the connective tissue attachment is not violated [5,6]. Human and animal research consistently shows stable attachment when the preparation remains within the sulcular epithelium [5,6], highlighting the importance of atraumatic technique and well-contoured provisional restorations.

Histological Evidence: Tissue Response to Vertical Preparation

Histology provides strong evidence supporting the biological safety of vertical preparation. In a human study, Agustín-Panadero et al. examined a tooth restored with BOPT and found normal epithelial and connective tissue architecture, absence of inflammation, and stable soft-tissue reattachment along the restoration’s vertical contour [5]. These findings indicate that vertical preparation does not harm gingival tissues when the connective tissue attachment is respected and provisional contours are correctly shaped.

Clinical Outcomes and Gingival Margin Stability

Clinical studies offer valuable long-term data on gingival behavior around vertically prepared teeth. A 2-year prospective study on zirconia crowns placed with BOPT reported that 80.5% of teeth showed no bleeding or inflammation, gingival thickness increased by about 0.4 mm, and recession was minimal, with biological complications occurring in only 2% of cases [3]. Longer follow-ups by Serra-Pastor et al. demonstrated similar outcomes: both the 4-year and 6-year studies showed low inflammation, stable gingival margins, high prosthetic survival, and good esthetic integration [1,4].

A meta-analysis by Al-Haddad et al. further confirmed that periodontal health around vertical preparations is comparable to chamfer preparations, with low biological complication rates [2]. Together, these results indicate that vertical preparation is biologically predictable when performed correctly.

Vertical crown preparation offers several biologic and esthetic advantages. It allows clinicians to guide the final gingival margin through the contour of the provisional restoration, which is especially useful in cases with uneven gingival levels or thin biotypes [1,3]. Studies also show slight gingival thickening after BOPT, contributing to improved long-term esthetic stability [3,4].

However, the technique has important limitations. It is highly operator-sensitive, and poor provisionalization can cause soft-tissue irritation and inflammation [3,5,6]. Deeper subgingival margins increase the difficulty of removing excess cement, raising the risk of biological complications [2].

Discussion

Current evidence indicates that vertical crown preparation, when performed within biologically safe limits, has a positive or neutral effect on gingival tissues. Histological studies show that the sulcular epithelium can reattach and reorganize around the vertical contour as long as the connective tissue attachment remains intact [5,6]. Long-term clinical studies (2–6 years) further demonstrate stable gingival margins, low inflammation, and minimal recession around BOPT restorations [1,3,4].

Biologically, the key factor is not the absence of a horizontal finish line but the preservation of the supra-crestal tissue attachment and proper shaping of the provisional restoration, which guides tissue remodeling and final margin position [1,3]. Predictability depends on careful technique: respecting sulcus depth, avoiding trauma to connective tissue, ensuring smooth restoration surfaces, and removing excess cement thoroughly. When these principles are followed, vertical preparation becomes a reliable option, especially in esthetic cases where soft-tissue stability is essential.

Conclusion

Vertical crown preparation represents a biologically compatible method for managing gingival tissues around fixed prostheses. Evidence from histological, clinical, and long-term follow-up studies indicates that gingival tissues can adapt well to vertical contours, often demonstrating stability and slight thickening over time.

References:

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